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Study on the hardening mechanism of cement asphalt binder
Institute of Scientific and Technical Information of China (English)
The hydration and hardening mechanism of cement asphalt binder(CAB) was studied.The early hydration process,hydration products and paste microstructure of CAB made by Portland cement and anionic asphalt emulsion were investigated by calorimetry,X-ray diffraction,and environmental scanning electron microscopy.The early hydration process of CAB can be characterized as 5 stages similar to those of Portland cement.There is no chemical reaction detected between cement and asphalt,hence no new hydration products other than those of Portland cement are produced.The hardening of CAB begins with the hydration of cement.When the hydration of cement comes into the acceleration period and its exothermic rate comes to the maximum,the coalescence of asphalt particles in asphalt emulsion is triggered.In the hardened system of CAB,it was found that the hydration products of cement form the skeleton and are covered by the continuous asphalt film.They formed an interpenetrating network system.The emulsifiers in the asphalt emulsion may retard the hydration process of cement.
The effect of cyclic hardening on fatigue properties of modified asphalt
Institute of Scientific and Technical Information of China (English)
The phenomenon of cyclic hardening is observed in fatigue tests of modified asphalt controlled by low strain/stress level and it is not clear how the phenomenon affects the fatigue properties of binders. The special time weep tests were performed to investigate the point. Tests results indicate that the cyclic hardening is caused by the rearrangement of molecules in binders, and it can make the inner structure of binders getting stable and increase the fatigue properties of asphalt binders. But fatigue damage occurs when fatigue tests start, no matter the phenomenon of cyclic hardening happens or not. If the controlled load is low, the effect of rearrangement of molecules on material is beyond the effect of fatigue damage so that the cyclic hardening can be observed. When the load conditions get worse, the effect of slight fatigue damages produced in hardening stage will show.
Oxidation hardening kinetics of the rheological function G'/('/G') in asphalts
Juristyarini, Pramitha
The authors used 9 asphalts oxidized at various temperatures and pressures to determine the hardening kinetics for the DSR function, an easily measured and meaningful surrogate for 15C ductility that relates well to age-related binder deterioration. For each asphalt, there is a rapid initial period that slows to a constant rate period. This constant rate period can be represented by carbonyl formation (oxidation) rate times a hardening susceptibility (HS). For the DSR function and viscosity, the HS and initial jump were pressure-but not temperature-dependent. The DSR function initial jump was relatively higher than the viscosity initial jump. © 2011 Taylor & Francis Group, LLC.
... petroleum material that hardens when it cools. Asphalt cement poisoning occurs when someone swallows asphalt. If hot ... found in: Road paving materials Roofing materials Tile cements Asphalt may also be used for other purposes.
A review of asphalt and asphalt mixture aging
Directory of Open Access Journals (Sweden)
Wilmar Darío Fernández-Gómez
Full Text Available This paper presents an extensive review of the pertinent literature regarding asphalt and asphalt mixture Aging. Aging affects flexible pavement performance and is produced by intrinsic and extrinsic variables as well as exposure time. Intrinsic variables include asphalt and aggregate properties, a mixture's asphalt content, binder film thickness and air void content; extrinsic variables are associated with production (short-term aging and exposure to environmental field conditions (long-term aging. Taken together, both variables demonstrate that aging results from three distinct mechanisms: volatilisation, oxidation and steric hardening. Temperature, pressure and photo degradation treatments are used to simulate aging in the laboratory and empirical and semi-empirical models are created to represent and study aging. Aging increases asphalt complex modulus and decreases the phase angle. Mixtures become stiffer while fatigue life becomes reduced. Carbonyl and sulfoxide group formation in asphalt are often studied as such chemical changes show oxidation in aged asphalts. The prevailing models used to predict asphalt aging are discussed, though more comprehensive research into asphalt aging is still needed.
Asphalt solar collectors: A literature review
Bobes-Jesús, Vanesa; Pascual Muñoz, Pablo; Castro Fresno, Daniel; Rodríguez Hernández, Jorge
Asphalt pavements subject to solar radiation can reach high temperatures causing not only environmental problems such as the heat island effect on cities but also structural damage due to rutting or hardening as a result of thermal cycles. Asphalt solar collectors are doubly effective active systems: as they solve the previously mentioned problems and, moreover, they can harness energy to be used in different applications. The main findings of the existing research on asphalt solar collectors...
Asphalt solar collectors: A literature review
International Nuclear Information System (INIS)
Highlights: ► Solar energy can be harnessed by asphalt pavements. ► Research on asphalt thermal behavior and asphalt solar collectors is reviewed. ► Asphalt temperature is very sensitive to the variation of absortivity. ► Asphalt solar collector efficiency depends on flow rate and geometrical parameters. -- Abstract: Asphalt pavements subject to solar radiation can reach high temperatures causing not only environmental problems such as the heat island effect on cities but also structural damage due to rutting or hardening as a result of thermal cycles. Asphalt solar collectors are doubly effective active systems: as they solve the previously mentioned problems and, moreover, they can harness energy to be used in different applications. The main findings of the existing research on asphalt solar collectors are gathered together in this review paper. Firstly, the main heat transfer mechanisms involved in the solar energy collection process are identified and the most important parameters and variables are presented. After analyzing the theoretical foundations of the heat transfer process, this review focuses on the types of studies carried out so far on asphalt's thermal behavior, different methodologies employed by other authors to study asphalt solar collectors and influence of the variables involved in thermal energy harvesting.
Dynamic linear viscoelastic properties and extensional failure of asphalt binders
Ruan, Yonghong
Billions of dollars are spent annually in USA to maintain old pavements that are badly cracked. In order to reduce this expenditure, it is desirable to have criteria for selecting asphalts with superior cracking resistance that will provide pavements with longer durability. Literature reports indicate that the ductility of binders recovered from asphalt pavements correlates with cracking failure. However, ductility measurement is a time and material consuming process, and subject to reproducibility difficulties, as are all failure tests. In addition, ductility measurement does not belong to the currently used Superpave(TM) specification. Correlations between ductility and dynamic viscoelastic properties (measured with the dynamic shear rheometer, DSR), which are much easier and faster to perform and may be included into the Superpave(TM) system, are studied for both straight and modified binders. Ductility correlates quite well with G'/(eta '/G') for conventional asphalt binders aged at different conditions, especially when ductility is below 10 cm. However, for modified asphalts, there is no universal correlation between ductility and G'/(eta'/G'), even in the low ductility region. As far as the asphalt binder in pavement is concerned, the loss due to oxidative aging of its ductility is an important reason for pavement cracking. Polymer modification modifies the rheological and oxidative hardening properties of asphalt binders. The effect of polymeric modifiers on various properties of asphalt binders was investigated. Modifiers studied were diblock poly (styrene-b-butadiene) rubber (SBR), triblock poly (styrene-b-butadiene-b-styrene) (SBS), and tire rubber. Polymer modified binders have a lower hardening and oxidation rate than their corresponding base asphalts. In addition, modified binders have lower hardening susceptibility compared with their base materials and in some cases the results can be dramatic. Polymer modification improves asphalt binders' shear
Asphalt Inst., College Park, MD.
The new and completely revised edition of the Asphalt Handbook, a standard reference work in the field of asphalt technology and construction, summarizes with reference the information contained in other Asphalt Institute technical manuals. Major areas discussed include the following--(1) uses of asphalt, (2) terms relating to asphalt and its…
GREENPATCH® - Cold Mix Asphalt
ECT Team, Purdue
GreenPatch® is environmentally friendly cold asphalt that is a direct replacement for traditional cold patch in repairing asphalt pavements. This revolutionary breakthrough in the cold asphalt industry contains no petroleum based softeners such as diesel, toluene, kerosene, and naphthalene found in conventional cold asphalt that pose serious threats to human health and the environment.
Low temperature asphalt mixtures
Modrijan, Damjan
This thesis presents the problem of manufacturing and building in the asphalt mixtures produced by the classical hot procedure and the possibility of manufacturing low temperature asphalt mixtures.We will see the main advantages of low temperature asphalt mixtures prepared with bitumen with organic addition Sasobit and compare it to the classical asphalt mixtures. The advantages and disadvantages of that are valued in the practical example in the conclusion.
Performance of asphalt rubber mixtures
Thives, Liseane Padilha; Trichês, Glicério; Pereira, Paulo A. A.; Pais, Jorge C.
Asphalt rubber mixtures are one of the most promising techniques to extend the service life of asphalt pavement overlays. Asphalt rubber binder is composed of crumb rubber from reclaimed tires and conventional asphalt. The asphalt rubber binder can be obtained through wet process in two different systems: terminal blending (produced at industrial plants) and continuous blending (produced in asphalt plants). This study presents a laboratory evaluation of asphalt rubber mixtures produced with d...
Asphalt in Pavement Maintenance.
Asphalt Inst., College Park, MD.
Maintenance methods that can be used equally well in all regions of the country have been developed for the use of asphalt in pavement maintenance. Specific information covering methods, equipment and terminology that applies to the use of asphalt in the maintenance of all types of pavement structures, including shoulders, is provided. In many…
Evaluation of an eastern shale oil residue as an asphalt additive
Energy Technology Data Exchange (ETDEWEB)
Thomas, K.P.; Harnsberger, P.M.
An evaluation of eastern shale oil (ESO) residue as an asphalt additive to reduce oxidative age hardening and moisture susceptibility was conducted by Western Research Institute (WRI). The ESO residue, have a viscosity of 23.9 Pa{lg_bullet}s at 60{degree}C (140{degree}F), was blended with three different petroleum-derived asphalts, ASD-1, AAK-1, and AAM-1, which are known to be very susceptible to oxidative aging. Rheological and infrared analyses of the unaged and aged asphalts and the blends were then conducted to evaluate oxidative age hardening. In addition, the petroleum-derived asphalts and the blends were coated onto three different aggregates, Lithonia granite (RA), a low-absorption limestone (RD), and a siliceous Gulf Coast gravel (RL), and compacted into briquettes. Successive freeze-thaw cycling was then conducted to evaluate the moisture susceptibility of the prepared briquettes. The rheological analyses of the unaged petroleum-derived asphalts and their respective blends indicate that the samples satisfy the rutting requirement. However, the aging indexes for the rolling thin film oven (RTFO)-aged and RTFO/pressure aging vessel (PAV)-aged samples indicate that the blends are stiffer than the petroleum-derived asphalts. This means that when in service the blends will be more prone to pavement embrittlement and fatigue cracking than the petroleum-derived asphalts. Infrared analyses were also conducted on the three petroleum-derived asphalts and the blends before and after RTFO/PAV aging. In general, upon RTFO/PAV aging, the amounts of carbonyls and sulfoxides in the samples increase, indicating that the addition of the ESO residue does not mitigate the chemical aging (oxidation) of the petroleum-derived asphalts. This information correlates with the rheological data and the aging indexes that were calculated for the petroleum-derived asphalts and the blends.
Laboratory performance of asphalt rubber mixtures
Fontes, Liseane; Trichês, Glicério; Pais, Jorge; Pereira, Paulo; Minhoto, Manuel
Asphalt rubber mixtures are one of the most promising techniques to extend the service life of asphalt pavement overlays. Asphalt rubber binder is composed of crumb rubber from reclaimed tires and conventional asphalt. The asphalt rubber binder can be obtained through wet process in two different systems: tire rubber modified asphalt binder (produced at industrial plants) and continuous blending (produced in asphalt plants). This study presents a laboratory evaluation of asphalt rubber mixtur...
Asphalt chemical fractionation
International Nuclear Information System (INIS)
Asphalt fractionation were carried out in the Esmeraldas Oil Refinery using n-pentane, SiO2 and different mixture of benzene- methane. The fractions obtained were analyzed by Fourier's Transformed Infrared Spectrophotometry (FTIR)
Modified Asphalt Binder with Natural Zeolite for Warm Mix Asphalt
Dubravský, Marián; Mandula, Ján
In recent years, warm mix asphalt (WMA) is becoming more and more used in the asphalt industry. WMA provide a whole range of benefits, whether economic, environmental and ecological. Lower energy consumption and less pollution is the most advantages of this asphalt mixture. The paper deals with the addition of natural zeolite into the sub base asphalt layers, which is the essential constituent in the construction of the road. Measurement is focused on basic physic - mechanical properties declared according to the catalog data sheets. The aim of this article is to demonstrate the ability of addition the natural zeolite into the all asphalt layers of asphalt pavement. All asphalt mixtures were compared with reference asphalt mixture, which was prepared in reference temperature.
A review of asphalt and asphalt mixture aging
Wilmar Darío Fernández-Gómez; Hugo Alexander Rondón Quintana; Fredy Reyes-Lizcano
This paper presents an extensive review of the pertinent literature regarding asphalt and asphalt mixture Aging. Aging affects flexible pavement performance and is produced by intrinsic and extrinsic variables as well as exposure time. Intrinsic variables include asphalt and aggregate properties, a mixture's asphalt content, binder film thickness and air void content; extrinsic variables are associated with production (short-term aging) and exposure to environmental field conditions (long-ter...
Modified Asphalt Binder with Natural Zeolite for Warm Mix Asphalt
Dubravský Marián; Mandula Ján
In recent years, warm mix asphalt (WMA) is becoming more and more used in the asphalt industry. WMA provide a whole range of benefits, whether economic, environmental and ecological. Lower energy consumption and less pollution is the most advantages of this asphalt mixture. The paper deals with the addition of natural zeolite into the sub base asphalt layers, which is the essential constituent in the construction of the road. Measurement is focused on basic physic – mechanical properties decl...
Asphalt for draining pavement; Haisuisei hosoyo asphalt
Energy Technology Data Exchange (ETDEWEB)
Yamamori, H.; Nakamura, Y. [Mitsubishi Oil Co. Ltd., Tokyo (Japan)
The effect and functions of draining pavement with a superb performance as a paved road were introduced. In the draining pavement, a porous asphalt mixture was used for the surface and base layers of the road and the remaining layers are not in water penetration property. It is necessary that void continues to prevent water film from being generated when rain falls and resistance against water flow is small but durability has problems when the void rate is large. According to the balance, the void rate ranges from 20 to 23 % for execution, thus preventing water splash on a rainy day, hydroplaning, and dazzlement, etc. due to reflection of light. The noise during driving due to the tire of an automobile is reduced by 5 to 6 dB owing to draining pavement. Also, engine noise is reduced to 40 - 60 % since the surface is porous. In the draining pavement, a high-viscosity asphalt is used for a binder and the void rate is large, thus preventing temperature to rise easily due to heat release and achieving an improved flow behavior. 6 refs., 11 figs., 14 tabs.
Compressive Strength Development and Microstrueture of Cement.asphalt Mortar
Institute of Scientific and Technical Information of China (English)
WANG Qiang; YAN Peiyu; KONG Xiangming; YANG Jinbo
The compressive strength developing process and the microstructure of cement-asphalt mortar (CA mortar) were investigated.The fluidity of CA mortar has a great influence on its strength.The optimum value of spread diameter of slump flow test is in the range of 300 to 400 mm.The compressive strength of CA mortar keeps a relatively high growth rate in 56 days and grows slowly afterwards.The residual water of hydration in CA mortar freezes under minus environmental temperature which can lead to a significant reduction of the strength of CA mortar.Increasing A/C retards asphalt emulsion splitting and thus prolongs the setting process of CA mortar.The hydration products of cement form the major structural framework of hardened CA mortar and asphalt is a weak phase in the framework but improves the viscoelastic behavior of CA mortar.Therefore,asphalt emulsion should be used as much as possible on the condition that essential performance criterions of CA mortar are satisfied.
Microstructure - based continuum damage model for Asphalt mixes
International Nuclear Information System (INIS)
Full text.Hot mix asphalt (HMA) is a complex composite material that consists of different sizes of aggregates, asphalt binder and air voids. One of the most important failures in asphalt pavements is caused by permanent deformation under high service temperature. An HMA with high resistance to permanent deformation work-hardens under repeated loading with accumulating strain. However, HMA that is susceptible to permanenr deformation develop microcracks under repeated loading, which softens the mix and leads ao an increase in the rate of accumulated strain. Most of macroscopic response of HMA, assume isotropic material properties and do not account for the microscopic behavior. This study develops a viscoplastic constitutive model for asphalt mixtures that incorporates microstructure parameters. The model is based on Perzyna's elasto-viscoplastic theory. The viscous flow function is extended to reflect the microstructure anisotropy. In addition, a damage parameter is included in the model to reflect the initiation adn propagation of cracks. The model's parameters are obtained using image analysis procedures, static creep tests and strength tests. The model is used to describe the behavior of number of mixtures with known field performance
[Hardening of dental instruments].
Gerasev, G P
The possibility of prolonging the service life of stomatological instruments by the local hardening of their working parts is discussed. Such hardening should be achieved by using hard and wear-resistant materials. The examples of hardening dental elevators and hard-alloy dental drills are given. New trends in the local hardening of instruments are the treatment of their working parts with laser beams, the application of coating on their surface by the gas-detonation method. The results of research work and trials are presented.
Analysis of asphalt mixtures on town roads
Glavica, Primož
Asphalt mixtures are most commonly used composite for construction of top layers of different drive ways. By definition asphalt mixtures are composed of crushed rock, fill, bitumen and additives. Percentage of individual components wary according to the purpose asphalt mixture is to be used for. Asphalt mixtures must be capable of enduring different types of load. According to the type of load asphalt mixtures are divided into asphalt mixtures used for supporting layers and asp...
Laboratory evaluation of selected tar sand asphalts
Energy Technology Data Exchange (ETDEWEB)
Button, J.W.; Epps, J.A.; Gallaway, B.M.
Three tar sand asphalts of similar grades prepared from one syncrude by three different refining methods were characterized by tests commonly used to specify paving asphalts together with certain special tests. Asphalt-aggregate mixtures were prepared using these asphalts and tested in the laboratory to determine strength stiffness stability, tensile properties, temperature effects and water susceptibility. Comparison of the tar sand asphalt properties to conventional petroleum asphalt properties reveal no striking differences.
Evaluation of an eastern shale oil residue as an asphalt additive
Energy Technology Data Exchange (ETDEWEB)
Thomas, K.P.; Harnsberger, P.M.
An evaluation of eastern shale oil (ESO) residue as an asphalt additive to reduce oxidative age-hardening and moisture susceptibility was conducted. The ESO residue, having a viscosity of 23.9 Pa{sm_bullet}s at 60{degrees}C (140{degrees}F), was blended with three different petroleum-derived asphalts, AAD-1, AAK-1, and AAM-1, that are known to be very susceptible to oxidative aging. Rheological and infrared analyses of the unaged and aged asphalts and the blends were then conducted to evaluate oxidative age-hardening. In addition, the petroleum-derived asphalts and the blends were coated onto three different aggregates, Lithonia granite (RA), a low-absorption limestone (RD), and a silicious Gulf Coast gravel (RL), and compacted into briquets. Successive freeze-thaw cycling was then conducted to evaluate the moisture susceptibility of the prepared briquets. The abbreviations used above for the asphalts and the aggregates are part of the Strategic Highway Research Program nomenclature.
Polymer Blends Modified Asphalt
Institute of Scientific and Technical Information of China (English)
@@ Asphalt is an important low-cost thermo-plastic material which is widely used for construction, in particular as road-paving. Therefore it is exposed to a wide range of load and weather conditions. Increasing traffic factors, such as heavier loads, higher traffic volume and higher tire pressure demand higher performance pavements. However, this kind of materials does not have good mechanical properties because it is hard and brittle in cold weather, and soft and fluid in a hot environment.
Effect of Crumb Rubber and Warm Mix Additives on Asphalt Aging, Rheological, and Failure Properties
Agrawal, Prashant
Asphalt-rubber mixtures have been shown to have useful properties with respect to distresses observed in asphalt concrete pavements. The most notable change in properties is a large increase in viscosity and improved low-temperature cracking resistance. Warm mix additives can lower production and compaction temperatures. Lower temperatures reduce harmful emissions and lower energy consumption, and thus provide environmental benefits and cut costs. In this study, the effects of crumb rubber modification on various asphalts such as California Valley, Boscan, Alaska North Slope, Laguna and Cold Lake were also studied. The materials used for warm mix modification were obtained from various commercial sources. The RAF binder was produced by Imperial Oil in their Nanticoke, Ontario, refinery on Lake Erie. A second commercial PG 52-34 (hereafter denoted as NER) was obtained/sampled during the construction of a northern Ontario MTO contract. Some regular tests such as Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR), Multiple Stress Creep Recovery (MSCR) and some modified new protocols such as the extended BBR test (LS-308) and the Double-Edge Notched Tension (DENT) test (LS-299) are used to study, the effect of warm mix and a host of other additives on rheological, aging and failure properties. A comparison in the properties of RAF and NER asphalts has also been made as RAF is good quality asphalt and NER is bad quality asphalt. From the studies the effect of additives on chemical and physical hardening tendencies was found to be significant. The asphalt samples tested in this study showed a range of tendencies for chemical and physical hardening.
Modeling Recycling Asphalt Pavement Processing Technologies in Asphalt Mixing Plants
Simonas Tamaliūnas; Henrikas Sivilevičius
The article presents reclaimed asphalt pavement (RAP) processing technologies and equipment models used in the asphalt mixing plant (AMP). The schematic model indicating all possible ways to process RAP in AMP is shown. The model calculating the needed temperature of mineral materials used for heating RAP is given and an example of such calculation is provided.Article in Lithuanian
Performance prediction of hot mix asphalt from asphalt binders
International Nuclear Information System (INIS)
Asphalt binder being a high weight hydrocarbon contains asphaltene and maltene and is widely used as cementing materials in the construction of flexible pavements. Its performance in hot mix asphalt also depends on combining with different proportions of aggregates. The main objective of this study was to characterize asphalt cement rheological behavior and to investigate the influence of asphalt on asphalt-aggregate mixtures prepared with virgin binders and using polymers. Binder rheology and mixtures stiffness were determined under a range of cyclic loadings and temperature conditions. Master curves were developed for the evaluation of relationship between parameters like complex modulus and phase angle at different frequencies. Horizontal shift factors were also computed to determine time and temperature response of binders and mixes. The results showed that the stiffness of both the binder and the mixes depends on temperature and frequency of load. Polymer modified binder is least susceptible to temperature variations as compared to other virgin asphalt cement. Performance of asphalt mixtures can be predicted from those of asphalt binders using the master curve technique. (author)
Evaluation of Thermal Oxidative Aging Effect on the Rheological Performance of Modified Asphalt Binders
Zhu, Cheng
Modified asphalt binder, which is combined by base binder and additive modifier, has been implemented in pavement industry for more than 30 years. Recently, the oxidative aging mechanism of asphalt binder has been studied for several decades, and appreciable finding results of asphalt binder aging mechanism were achieved from the chemistry and rheological performance aspects. However, most of these studies were conducted with neat binders, the research of aging mechanism of modified asphalt binder was limited. Nowadays, it is still highly necessary to clarify how the asphalt binder aging happens with the modified asphalt binder, what is the effect of the different modifiers (additives) on the binder aging process, how the rheological performance changes under the thermal oxidative aging conditions and so on. The objective of this study was to investigate the effect of isothermal oxidative aging conditions on the rheological performance change of the modified and controlled asphalt binders. There were totally 14 different sorts of asphalt binders had been aged in the PAV pans in the air-force drafted ovens at 50°C, 60°C and 85°C for 0.5 day to 240 days. The Fourier-Transform Infrared Spectroscopy (FT-IR) and Dynamic Shear Rheometer (DSR) were used to perform the experiments. The analysis of rheological indices (Low shear viscosity-LSV, Crossover modulus-G*c, Glover-Rowe Parameter-G-R, DSR function-DSR Fn) as a function of carbonyl area (CA) was conducted. With the SBS modification, both of the hardening susceptibility of the rheological index-LSV and G-R decreases compared with the corresponding base binder. The TR increased the hardening susceptibility of all the rheological indexes. While for the G*c, SBS increases the slope of the most modified asphalt binders except A and B_TR_X series binders. The multiple linear regression statistical analysis results indicate that the oxidative aging conditions play an important role on the CA, and rheological performance
Dead sea asphalts: historical aspects
Energy Technology Data Exchange (ETDEWEB)
Nissenbaum, A.
Asphalts are present in the Dead Sea basin in three forms: (1) huge blocks, up to 100 tons in weight, composed of extremely pure (>99.99%) solid asphalt occasionally found floating on the lake, (2) veins, seepages, and cavity and fissure fillings in Lower Cretaceous to Holocene rocks, and (3) ozocerite veins on the eastern shore of the lake. Dead Sea asphalts probably have been documented over a longer period of time than any other hydrocarbon deposit--from antiquity to the 19th century. Major uses of asphalt from the Dead Sea have been as an ingredient in the embalming process, for medicinal purposes, for fumigation, and for agriculture. The first known war for control of a hydrocarbon deposit was in the Dead Sea area in 312 B.C. between the Seleucid Syrians and the Nabatean Arabs who lived around the lake. Surface manifestations of asphalt are linked closely to tectonic activity. In the lake itself, the asphalt is associated with diapirs During certain historic periods, tectonic and diapiric activity caused frequent liberation to the Dead Sea surface of semiliquid asphalt associated with large amounts of hydrogen sulfide gas. When the tectonic activity was attenuated, as in the 19th and 20th centuries, the rate of asphalt seepage to the bottom sediments of the Dead Sea was much slower and the asphalt solidified on the lake bottom. The release of asphalt to the surface became much more sporadic, and may have resulted in part from earthquakes. Thus, future asphalt prospecting in the Dead Sea area should be conducted along the boundaries of diapirs or their associated faults.
Polyurethane synthesis reactions in asphalts
Energy Technology Data Exchange (ETDEWEB)
Bukowski, A.; Gretkiewicz, J.
A series of asphalt-polyurethane composites was prepared by means of polyurethane synthesis in asphalt and carried out in melt. The applied materials were asphalts of differentiated group components content, polyester polyols of chain structure from linear to strongly branched, 2,4-tolylene diisocyanate, 4,4-methylenebis(phenyl isocyanate), and tinorganic catalyst. The asphalt components react with isocyanates to a minimal degree. The influence of the applied substrates, temperature, and polyurethane content in the system on the basic kinetic relations characterizing the process is presented. Polyurethane synthesis in asphalts does not differ in a fundamental way from the obtaining of polyurethanes, especially when their content in the composition is significant, 20 wt% and more.
Preparation and properties of montmorillonite modified asphalts
International Nuclear Information System (INIS)
Modified asphalts were prepared by melt blending with different contents of montmorillonite (MMT) and organomodified montmorillonite (OMMT). The X-ray diffraction (XRD) results show that the MMT modified asphalt may form an intercalated structure, whereas the OMMT modified asphalt may form an exfoliated structure. The addition of MMT and OMMT to asphalt increases both the softening point and viscosity of the modified asphalts at high temperatures. Furthermore, the modified asphalts exhibited higher complex modulus, lower phase angle. As a consequence, the MMT and OMMT modified asphalts displays enhanced viscoelastic properties, which improve its resistance to rutting at high temperatures. Compared with MMT, OMMT showed better effect in improving softening point and rutting resistance of asphalt, which contributes to the formation of exfoliated structure in OMMT modified asphalt. Storage stability tests disclose that the asphalts modified with MMT or OMMT are very stable when montmorillonite content is less than 3 wt%
Institute of Scientific and Technical Information of China (English)
Institute for Laser Physics; V.A.Serebryakov; K.V.Gratzianov; A.S.Eremenko; A.A.Timopheev; SPBSUITMO; M.V.Volkov
Results of experiments on laser hardening of various materials with intensity 109~1010W/cm2 are represented. Nd:glass laser with energy up to 45J with a pulse duration ~30ns was used as a source of ra diation. Comparative researches of the laser peening for the various target areas are fulfilled. Results of laser hardening were determined by the microstructure analysis. The new approach to creation of the industrial laser for peening is discussed.
Asphalt Mixture for the First Asphalt Concrete Directly Fastened Track in Korea
Seong-Hyeok Lee; Dae-Wook Park; Hai Viet Vo; Samer Dessouky
The research has been initiated to develop the asphalt mixtures which are suitable for the surface of asphalt concrete directly fastened track (ADFT) system and evaluate the performance of the asphalt mixture. Three aggregate gradations which are upper (finer), medium, and below (coarser). The nominal maximum aggregate size of asphalt mixture was 10 mm. Asphalt mixture design was conducted at 3 percent air voids using Marshall mix design method. To make impermeable asphalt mixture surface, th...
Polymer Blends Modified Asphalt
Institute of Scientific and Technical Information of China (English)
WANG; YunPu
Asphalt is an important low-cost thermo-plastic material which is widely used for construction, in particular as road-paving. Therefore it is exposed to a wide range of load and weather conditions. Increasing traffic factors, such as heavier loads, higher traffic volume and higher tire pressure demand higher performance pavements. However, this kind of materials does not have good mechanical properties because it is hard and brittle in cold weather, and soft and fluid in a hot environment. ……
Investigation of modified asphalt concrete
Zimich, Vita
Currently the problem of improving the asphalt quality is very urgent. It is used primarily as topcoats exposed to the greatest relative to the other layers of the road, dynamic load - impact and shear. The number of cars on the road, the speed of their movement, as well as the traffic intensity increase day by day. We have to upgrade motor roads, which entails a huge cost. World experience shows that the issue is urgent not only in Russia, but also in many countries in Europe, USA and Asia. Thus, the subject of research is the resistance of asphalt concrete to water and its influence on the strength of the material at different temperatures, and resistance of pavement to deformation. It is appropriate to search for new modifiers for asphaltic binder and mineral additives for asphalt mix to form in complex the skeleton of the future asphalt concrete, resistant to atmospheric condensation, soil characteristics of the road construction area, as well as the growing road transport load. The important task of the work is searching special modifying additives for bitumen binder and asphalt mixture as a whole, which will improve the quality of highways, increasing the period between repairs. The methods described in the normative-technical documentation were used for the research. The conducted research allowed reducing the frequency of road maintenance for 7 years, increasing it from 17 to 25 years.
Gaurav, Suraj
Learn what it takes to build large scale, mission critical applications -hardened applications- on the Azure cloud platform. This 208 page book covers the techniques and engineering principles that every architect and developer needs to know to harden their Azure/.NET applications to ensure maximum reliability and high availability when deployed at scale. While the techniques are implemented in .NET and optimized for Azure, the principles here will also be valuable for users of other cloud-based development platforms. Applications come in a variety of forms, from simple apps that can be bui
Determination of the asphalt content of the asphalt concrete by surface neutron gauge
International Nuclear Information System (INIS)
This paper describes the principle, calibration and field detection of determining the asphalt content of asphalt concrete by surface neutron gauge. This method can be utilized to measure the asphalt content for asphalt concrete dams, highways and airport runways to control the engineering quality
Concrete, hardened: Self desiccation
DEFF Research Database (Denmark)
Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard; Persson, Bertil
The test method covers the determination of internal relative humidity (RH) in hardened concrete and cement mortar using RH instruments. The determination of RH is done on crushed samples of concrete or cement motar. This test method is only for measuring equipment which gives off or takes up...
Self Healing Capacity of Asphalt Binders
Institute of Scientific and Technical Information of China (English)
PANG Ling; JIANG Huan; WU Shuxiang; WU Shaopeng
To test self healing capability of asphalt binders,three asphalt specimens (pure asphalt,modified asphalt and aged asphalt) were prepared.Every specimen was tested by dynamic shear rheometer (DSR).The temperature sweeps result indicates that both aging and SBS modifying influence the self healing capability of asphalt binder.The fatigue-heal-fatigue test was introduced to study the self healing capability of asphalt in its serving periods.Furthermore,three different periods (0.5 h,1 h,3 h) were set up to study the influence of rest time on fatigue time.It is concluded that longer rest time,less load will delay the appearance of cracks and extend the service life of asphalt binders.
Nanomaterials Applied in Asphalt Modification: A Review
Institute of Scientific and Technical Information of China (English)
Changqing Fang; Ruien Yu; Shaolong Liu; Yan Li
Nanotechnology has been gradually penetrated into the field of asphalt modification.Seemingly magic effects of nanomaterials have now been brought to improve the performance of asphalt.To demonstrate many of the prospective applications,researchers have conducted a series of positive and effective efforts dealing with the preparation of modified asphalt to demonstrate the mechanism of modification and the resultant improvement in performance.In this review,various nanomaterials used in asphalt modification are initially presented,followed by the methods employed to modify the asphalt with these materials and finally the effects of nanomaterials on the performance of base asphalt are presented and the modification mechanisms are discussed.Based on the current research results,the influence of preparation process parameters on the compatibility of every phase in the modified asphalt and the stability of the modified asphalt system are described.Finally,the development trend of the topic field is projected.
Laboratory aging of asphalt mixtures : simulation of reclaimed asphalt and application as test method for durability
Mollenhauer, Konrad; MOUILLET, Virginie; PIERARD, Nathalie; TUSAR, Marjan; Gabet, Thomas
Surface asphalt courses reach their end of service life after a time span between 10 and 30 years, depending on their durability. Afterwards, the surface layer is usually milled and reused in asphalt mixtures as reclaimed asphalt. In order to enable the analysis of durability and recyclability of a new asphalt mixture, four laboratory aging procedures were designed and comparatively applied on twoasphalt mixes. Besides aging of loose asphalt mix in heating cabinets at varied temperatures and ...
Laboratory optimization of continuous blend asphalt rubber
Fontes, Liseane P. T. L.; Pereira, Paulo A. A.; Trichês, Glicério; Pais, Jorge C.; Luzia, Rosa
Asphalt rubber from wet process requires batching blending and reaction time associated to blending rubber and conventional asphalt to produce asphalt rubber. The ideal blending of these materials depends on the combination of very important variables, such as the amount of rubber, reaction time and temperature reaction. This paper intends to optimize the laboratory production of asphalt rubber using the continuous blend process. The rubber from waste tyres was reduced by ambient grinding and...
Evaluating permanent deformation in asphalt rubber mixtures
Fontes, Liseane P. T. L.; Trichês, Glicério; Pais, Jorge C.; Pereira, Paulo A. A.
Permanent deformation or rutting, one of the most important distresses inflexible pavements, has long been a problem in asphalt mixtures. Throughout the years, researchers have used different test methods lo estimate the performance of asphalt mixtures in relation to rutting. One of the alternatives to reduce permanent deformation in asphalt pavement layers is through the use of mixtures produced with asphalt rubber This work aims at comparing the performance of a conventional dense graded mi...
Asphalt Carriers from Kraljevica Shipyard, Croatia
Grubišić, R.
This article is based on the materials presented by the experts from Kraljevica Shipyard at the annual meeting of the Croatian shipbuilding designers held in Kraljevica in October 2005. Asphalt tanker Asphalt Seminole and her sister-ships are rather sophisticated vessels having a complex hull structure, cargo space and cargo survey and control equipment. Therefore, firstly the technical data of the already delivered asphalt tanker Asphalt Seminole are given and then, the very interesting d...
Sinopec Launches Shanghai Asphalt Sales Company
Institute of Scientific and Technical Information of China (English)
@@ Sinopec Shanghai Asphalt Sales Company was launched in Shanghai on September 22, marking Sinopec as the largest asphalt supplier in China integrated in famous brand,production, sales and research, and distribution network.This is another important initiative for Sinopec's asphalt segment, after Sinopec won the bid for construction of F 1 racing course, to grasp the market opportunities, further improve the product quality and the level of after-sales services, and further make its asphalt business larger and stronger.
Floating asphalt blocks of the Dead Sea
Energy Technology Data Exchange (ETDEWEB)
Nissenbaum, A. (Weizmann Inst. of Science, Rehovot, Israel); Aizenshtat, Z.; Goldberg, M.
Large blocks of mineral matter free (less than 0.1%) asphalt are occasionally found floating on the surface of the Dead Sea. Chemical, spectroscopic and isotopic data are given for the asphalt. The source of the asphalt is not accurately known, but presumably it represents mobilization of heavy viscous asphaltic masses at depth below the lake bottom into the floor of the lake. It may be released to the surface by earth tremors.
The improvement of pavement performance using asphalt rubber hot mixes
Pais, Jorge C.; Pereira, Paulo A. A.
The need of a better pavement performance has led researchers to develop new road materials, mainly for the asphalt layers, where the modification of the asphalt is the main example. This modification usually forces the use of polymers and fibers and, more recently, the use of crumb rubber from ground tires, where the modified asphalt is known as asphalt rubber. This asphalt rubber used in asphalt mixtures produces a superior performance if compared to the asphalt mixtures with...
Initiative assessment of asphalt works
International Nuclear Information System (INIS)
Several asphalt works are utilizing heat from combustion of used oil for drying and heating of rock material in the production of asphalt. According to new regulations on combustion of waste, used oil is to be regarded as waste and subject to emission requirements according to the combustion regulations. Measurements show that emissions of CO, dust, dioxins, TOC and SO2 exceed the limits set by the regulations. To conform to the regulations these asphalt works must improve their combustion technique. However, such measures may lead to increased formation of NOx. It is recommended that a combustion chamber for drying of rock material should be used in order to reduce the emissions of CO and TOC concentrations. The concentration of SO2 may be reduced by dry cleaning by means of injection of lime. In the same way, active carbon is injected to remove dioxins. The asphalt works must be outfitted with measuring equipment that monitors and records certain operation and control parameters and some emission to air parameters. Periodic measurements are to be done of heavy metals and dioxins. It is estimated that the measures necessary to make the asphalt works comply with the regulations will cost about NOK 4 530 000 in investment per plant and that the operation expenses will increase by NOK 700 000 per year per plant. This includes maintenance, control etc
RHOBOT: Radiation hardened robotics
International Nuclear Information System (INIS)
A survey of robotic applications in radioactive environments has been conducted, and analysis of robotic system components and their response to the varying types and strengths of radiation has been completed. Two specific robotic systems for accident recovery and nuclear fuel movement have been analyzed in detail for radiation hardness. Finally, a general design approach for radiation-hardened robotics systems has been developed and is presented. This report completes this project which was funded under the Laboratory Directed Research and Development program
Salonitis, Konstantinos
This book presents the grind-hardening process and the main studies published since it was introduced in 1990s. The modelling of the various aspects of the process, such as the process forces, temperature profile developed, hardness profiles, residual stresses etc. are described in detail. The book is of interest to the research community working with mathematical modeling and optimization of manufacturing processes.
RHOBOT: Radiation hardened robotics
Energy Technology Data Exchange (ETDEWEB)
Bennett, P.C.; Posey, L.D. [Sandia National Labs., Albuquerque, NM (United States)
A survey of robotic applications in radioactive environments has been conducted, and analysis of robotic system components and their response to the varying types and strengths of radiation has been completed. Two specific robotic systems for accident recovery and nuclear fuel movement have been analyzed in detail for radiation hardness. Finally, a general design approach for radiation-hardened robotics systems has been developed and is presented. This report completes this project which was funded under the Laboratory Directed Research and Development program.
Waterproofing improvement of radioactive waste asphalt solid
International Nuclear Information System (INIS)
Purpose: To improve the waterproofing of asphalt solid by adding an alkaline earth metal salt and, further, paraffin, into radioactive liquid waste when processing asphalt solidification of the radioactive liquid waste. Method: Before processing molten asphalt solidification of radioactive liquid waste, soluble salts of alkaline earth metal such as calcium chloride, magnesium chloride, or the like is added to the radioactive liquid waste. Paraffin having a melting point of higher than 600C, for example, is added to the asphalt, and waterproofing can be remarkably improved. The waste asphalt solid thus fabricated can prevent the swelling thereof, and can improve its waterproofing. (Yoshihara, H.)
Thermal behavior of asphalt cements
International Nuclear Information System (INIS)
Asphalt cements are highly complex mixtures of hydrocarbon molecules whose thermal behavior is of prime importance for petroleum and road industry. From DSC, the determination of several thermal properties of asphalts is given, e.g. glass-transition temperature and crystallized fraction content.The dissolution of a pure n-paraffin CnH2n+2 in an asphalt, as seen by DSC, should be a single peak. For 20g of these glasses change with time and temperature. The formation of the crystallized phases is superposed to the enthalpic relaxation of the glasses, making a kinetic study very difficult. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)
Asphalt Mixture for the First Asphalt Concrete Directly Fastened Track in Korea
Directory of Open Access Journals (Sweden)
Seong-Hyeok Lee
Full Text Available The research has been initiated to develop the asphalt mixtures which are suitable for the surface of asphalt concrete directly fastened track (ADFT system and evaluate the performance of the asphalt mixture. Three aggregate gradations which are upper (finer, medium, and below (coarser. The nominal maximum aggregate size of asphalt mixture was 10 mm. Asphalt mixture design was conducted at 3 percent air voids using Marshall mix design method. To make impermeable asphalt mixture surface, the laboratory permeability test was conducted for asphalt mixtures of three different aggregate gradations using asphalt mixture permeability tester. Moisture susceptibility test was conducted based on AASHTO T 283. The stripping percentage of asphalt mixtures was measured using a digital camera and analyzed based on image analysis techniques. Based on the limited research results, the finer aggregate gradation is the most suitable for asphalt mixture for ADFT system with the high TSR value and the low stripping percentage and permeable coefficient. Flow number and beam fatigue tests for finer aggregate asphalt mixture were conducted to characterize the performance of asphalt mixtures containing two modified asphalt binders: STE-10 which is styrene-butadiene-styrene (SBS polymer and ARMA which is Crum rubber modified asphalt. The performance tests indicate that the STE-10 shows the higher rutting life and fatigue life.
Evaluation on Low Temperature Performance of Recycled Asphalt Mixture Using Warm Mix Asphalt Technology
Directory of Open Access Journals (Sweden)
Xiaolan Duan,
Full Text Available In this paper, the basic idea is about the recycled technology of asphalt mixture, more in-depth study of the lowtemperature performance of warm mix asphalt(WMA.First of all, Including the evaluation of low temperature performance of WMA made of reclaimed asphalt pavement (RAP (passed and not passed 2.36mm screen, and the influence of WMA with RAP mixed of different dosage of dispersant. Then, using the SBS modified asphalt and base asphalt were test at low temperature, research on the influence of different type of asphalt to the low temperature performance of WMA.
Rheological characteristics of aged asphalt binder
Institute of Scientific and Technical Information of China (English)
刘聪慧; 吴少鹏; 刘全涛; 朱国军
Different aging levels(RTFOT,PAV-10h,PAV-20h and PAV-30 h) of asphalt binders with various mass ratios of mineral powder to asphalt(0,0.4,0.8,1.2,1.6,2.0) were used to investigate the rheological properties of aged asphalt binders with respect to their short and long terms aging characteristics.Viscosity test,dynamic shear test and creep test were conducted.The test results indicate that the viscosity of aged asphalt binder increases sharply with the extension of aging period.Complex shear modulus of aged asphalt increases,which indicates that the stiffness of asphalt binders can increase.The phase angle for aged asphalt binders reduces,which indicates that the elastic portion for viscoelastic property of asphalt binders increases.|G*|·sin δ increases after aging procedure which means that the fatigue resistance becomes poor.The creep test results show that creep strain curves varies remarkably for virgin and aged asphalt binders.The total strain during loading period and the permanent strain decreases significantly for aged asphalt binders,which implies that the elastic portion increases and the viscous portion decreases.
The Development of Recycling Agent for Asphalt Pavement
Institute of Scientific and Technical Information of China (English)
A type of recycling agent was developed and its use for modifying used asphalt is described.The results show that the viscosity and three main properties of the aged asphalt were remarkably improved.With 5%-7% content of recycling agent, the main properties of recycled asphalt comported with China GB asphalt standard AH-70 and the recycled asphalt concrete could be used as high-grade highway.Furthermore,the recycling mechanism of the aged asphalt is discussed.
Evaluation of Marshall Properties of Warm Mix Asphalt using Sasobit
Renugadevi. A
With increasing concerns of global warming and increasing exhaustion of greenhouse gases, the asphalt industry is looking for alternatives for hot mix asphalt (HMA).Warm Mix Asphalt (WMA) is a fast emerging new technology which has a potential of revolutionizing the production of asphalt mixtures. WMA technology allows the mixing, lay down and compaction of asphalt mixes at significantly lower temperatures compared to Hot Mix Asphalt (HMA). The technology can reduce production tem...
Microstructural characterisation of rubber modified asphalt mixtures
Abdul Hassan, Norhidayah
Research to improve the performance of asphalt mixtures through the addition of crumb rubber using the dry process has continued worldwide because of its potential as a recycling option for used tires. For decades, dry mixed rubberised asphalt mixtures have performed inconsistently in field trials and laboratory evaluations. However, current research has revealed that the performance of asphalt mixtures is highly dependent on the characteristics of its internal structure or phase constituents...
Construction and maintenace of porous asphalt
Kert, Gregor
In improving traffic safety and reducing traffic noise road building experts from Slovenia and the world are faced with permeable surfaces - namely porous asphalt. There is hardly any water retention on road surfaces with the use of porous asphalt, what Slovenian engineers efficiently use on motorways where transverse profile changes its direction. Lately, porous asphalt is also being used for traffic noise reduction. However, porous road surface has some important disadvantages due to its...
Evaluation of Strain Hardening Parameters
Institute of Scientific and Technical Information of China (English)
DING Zong-hai; Pavel Huml; YANG Wei
The plane-strain compression test for three kinds of materials was carried out in a temperature range between room temperature and 400 ℃. The σ - ε curves and strain-hardening rate at different temperatures were simulated and a reasonable fit to the experimental data was obtained. A modified model created by data inference and computer simulation was developed to describe the strain hardening at a large deformation, and the predicted strain hardening are in a good agreement with that observed in a large range of stress. The influences of different parameters on strain hardening behaviour under large deformation were analysed. The temperature increase within the test temperatures for stainless steel 18/8 Ti results in dropping of flow stress and strain-hardening rate. For favourable γ-fibre texture to obtain high r, the cold rolling was applied at large reduction. In the experimental procedure, the X-ray diffraction test was carried out to compare the strain hardening and microstructure under large deformation for a bcc steel (low carbon steel SS-1142). The results indicate that the high strain-hardening rate possibly occurs when the primary slip plane {110} is parallel to the rolling plane and the strain-hardening rate decreases when lots of {110} plane rotate out from the orientation {110}∥RP.
Impact of defective production of asphalt mixture resulting in damaged asphalt layers
Hrovat, Tea
In practice it often happens that a newly built road soon, after the asphalt mixture is added, starts showing first cracks and damages, which are not necessarily always a fault of the contractor, who built in the asphalt mixture, but can derive from the production of asphalt mixture. Such mistakes in the production of the asphalt mixture are hard to prove, since all the contractors usually put the blame on the automatic mixing production in the asphalt plant. During the production of the asph...
Analysing polystyrene-modified asphalt and its incidence in a heat-dense asphalt mixture
Ana Sofía Figueroa Infante; Fredy Alberto Reyes Lizcano; Diana Hernández Barrera; Christian Jiménez; Natalia Bohórquez
This article presents some results obtained with an MDC-2 asphalt/polystyrene-modified asphalt mixture as a result of crushing waste glass. The stone, asphalt and polystyrene materials' were characterised for drawing up the design. The Marshal method was used for obtaining the best asphalt- stone-polystyrene percentages. The Superpave method was used for analysing the asphalt; the mixture's dynamic behaviour was analysed using a test involving 20ºC and 30ºC trapezoidal fatigue for 90x10-6, 15...
Evaluation on Low Temperature Performance of Recycled Asphalt Mixture Using Warm Mix Asphalt Technology
Xiaolan Duan,; Chunge Li
In this paper, the basic idea is about the recycled technology of asphalt mixture, more in-depth study of the lowtemperature performance of warm mix asphalt(WMA).First of all, Including the evaluation of low temperature performance of WMA made of reclaimed asphalt pavement (RAP) (passed and not passed 2.36mm screen), and the influence of WMA with RAP mixed of different dosage of dispersant. Then, using the SBS modified asphalt and base asphalt were test at low temperature, researc...
Rheological characterization of aged asphalts
International Nuclear Information System (INIS)
The present work shows the rheological properties of the three Colombian asphalts produced in the refineries at Barrancabermeja, Cartagena and Apiay, exposed to the open air during 18 months using a specially designed testing bank. rheological behavior was evaluated using the new specifications of SHRP technology in the Brookfield and DSR rheometers to determine viscosity, shear stress, shear rate, dynamic share modulus and other related variables. The measurements were made using different temperatures and load times
Resonance Testing of Asphalt Concrete
Gudmarsson, Anders
This thesis present novel non-destructive laboratory test methods to characterize asphalt concrete. The testing is based on frequency response measurements of specimens where resonance frequencies play a key role to derive material properties such as the complex modulus and complex Poisson's ratio. These material properties are directly related to pavement quality and used in thickness design of pavements. Since conventional cyclic loading is expensive, time consuming and complicated to perfo...
Asphalt solidification of mixed wastes
International Nuclear Information System (INIS)
Mixed wastes pose a problem to generators since there are no burial sites or treatment facilities currently accepting this waste type. One potential disposal method is treating the waste to render it non-hazardous, and disposing of it in accordance with radioactive waste requirements. A possible means of accomplishing this transformation is solidifying the waste in asphalt (bitumen). Associated Technologies Incorporated, in cooperation with Oak Ridge National Laboratory, solidified in asphalt a surrogate sodium nitrate-based waste, spiked with EPtoxic metals and non-radioactive cesium and strontium. This paper reports the characteristics of the spiked ORNL solution that was solidified as well as the properties of the solidified end product. The waste samples generated underwent EP toxicity testing as well as ANS 16.1 leach testing for 90 days and the results of those tests are presented. Also, a discussion of the criteria for classifying a waste as hazardous are included in order to demonstrate that the waste, once solidified in asphalt, may no longer be considered hazardous
Sustainable asphalt pavement: Application of slaughterhouse waste oil and fly ash in asphalt binder
Sanchez Ramos, Jorge Luis
Increasing energy costs, lack of sufficient natural resources and the overwhelming demand for petroleum has stimulated the development of alternative binders to modify or replace petroleum-based asphalt binders. In the United States, the petroleum-based asphalt binder is mainly used to produce the Hot Mix Asphalt (HMA). There are approximately 4000 asphalt plants that make 500 million tons of asphalt binder valued at roughly 3 billion/year. The instability of the world's oil market has pushed oil prices to more than 80 per barrel in 2012, which increased the cost of asphalt binder up to $570 per ton. Therefore, there is a timely need to find alternative sustainable resources to the asphalt binder. This paper investigates the possibility of the partial replacement of the asphalt binder with slaughterhouse waste and/or fly ash. In order to achieve this objective, the asphalt binder is mixed with different percentages of waste oil and/or fly ash. In order to investigate the effect of these additives to the performance of the asphalt binder, a complete performance grade test performed on multiple samples. The results of the performance grade tests are compared with a control sample to observe how the addition of the waste oil and/or fly ash affects the sample. Considering the increasing cost and demand of asphalt, the use of slaughterhouse waste oil and/or fly ash as a partial replacement may result in environmental and monetary improvements in the transportation sector.
Hot Mix Asphalt Recycling: Practices and Principles
Mohajeri, M.
Hot mix asphalt recycling has become common practice all over the world since the 1970s because of the crisis in oil prices. In the Netherlands, hot recycling has advanced to such an extent that in most of the mixtures more than 50% of reclaimed asphalt (RA) is allowed. These mixtures with such a hi
The report provides data from pilot-scale measurements of the emissions of specific air pollutants from paving asphalt both with and without recycled crumb rubber additives. The methods used in this work measured emissions from a static layer of asphalt maintained for several hou...
The report provides data from pilot-scale measurements of the emissions of specific air pollutants from paving asphalt both with and without recycled crumb rubber additives. he methods used in this work measured emissions from a static layer of asphalt maintained for several hour...
Asphalt Raking. Instructor Manual. Trainee Manual.
Laborers-AGC Education and Training Fund, Pomfret Center, CT.
This packet consists of the instructor and trainee manuals for an asphalt raking course. The instructor manual contains a course schedule for 4 days of instruction, content outline, and instructor outline. The trainee manual is divided into five sections: safety, asphalt basics, placing methods, repair and patching, and clean-up and maintenance.…
Environmental Benefits of Warm Mix Asphalt
Zaumanis, M; OLESEN, E
WMA is a relatively new technology that allows significant lowering of the production and pavement temperature of conventional hot mix asphalt (HMA). It promises various benefits, but probably the most significant is the possibility to reduce carbon footprint of asphalt thus supporting the demands of Kyoto protocol for lowering greenhouse gas emissions in the atmosphere.
Asbestos Tailings as Aggregates for Asphalt Mixture
Institute of Scientific and Technical Information of China (English)
LIU Xinoming; XU Linrong
To use many asbestos tailings collected in Ya-Lu highway, and to explore the feasibility of using asbestos tailings as aggregates in common asphalt mixtures, and properties of some asphalt mixtures were evaluated as well. X-ray diffraction (XRD), X-ray fluorescent (XRF), and atomic absorption spectrophotometry (AAS) were employed to determine the solid waste content of copper, zinc, lead, and cadmium. Volume properties and pavement performances of AC-25 asphalt mixture with asbestos tailings were also evaluated compared with those with basalt as aggregates.XRD and XRF measurement results infer that asbestos tailing is an excellent road material. Volume properties of AC-25 asphalt mixture with asbestos tailings satisfied the related specifications. No heavy metals and toxic pollution were detected in AAS test and the value of pH test is 8.23, which is help to the adhesion with asphalt in the asphalt concrete. When compared with basalt, high temperature property and the resistance to low temperature cracking of AC-25 asphalt mixture was improved by using asbestos tailings as aggregates. In-service AC-25 asphalt pavement with asbestos tailings also presented excellent performance and British Pendulum Number (BPN) coefficient of surface.
Rheological Evaluation of Polymer Modiifed Asphalt Binders
Institute of Scientific and Technical Information of China (English)
WANG Lan; CHANG Chunqing
The microstructure and dynamic rheological characteristics of asphalt containing different polymer modifiers (crumb rubber, styrene-butadiene-styrene and crumb rubber mix with styrene-butadiene-styrene) at mid and high service temperature levels were investigated by using scanning electron microscopy(SEM), dynamic shear rheometer(DSR) and repeat creep test. The main objective of the investigation was to rank the modifiers based on their effect on performance characteristics of asphalt under service conditions. To evaluate the effect of different modiifers on the viscoelastic response of asphalt, the temperature and frequency dependences of the dynamic viscoelastic properties were compared. The mid-temperature fatigue resistance and high-temperature rutting resistance of three polymer modiifed asphalts were evaluated to predict their ifeld performance in roads. Based on the current results, an improved rutting factor was proposed to determine the rutting resistance of asphalt pavements. In addition, the viscous stiffness (Gv), deifned as the reciprocal of viscous compliance, was used to evaluate the high-temperature deformation resistance of asphalt mixtures. The experimental results indicate that the asphalt containing crumb rubber only shows superior performance at mid and high service temperatures in all three modiifed asphalt binders due to the action of the crumb rubber.
Environmental Benefits of Warm Mix Asphalt (WMA)
Zaumanis, M; Olesen, E
Warm Mix Asphalt technology promises various benefits, but probably the most significant is the possibility to reduce carbon footprint of asphalt. The degree of emission reduction depends on the production technology, therefore life cycle assessment tool is vital to calculate the benefits and compare technologies.
Curing Reaction Model of Epoxy Asphalt Binder
Institute of Scientific and Technical Information of China (English)
QIAN Zhendong; CHEN Leilei; WANG Yaqi; SHEN Jialin
In order to understand the strength developing law of the epoxy asphalt mixture,a curing reaction model of the epoxy asphalt binder was proposed based upon the thermokinetic analysis.Given some assumptions,the model was developed by applying the Kissinger law as well as Arrhenius equation,and the differential scanning calorimetry was performed for estimating the model parameters.To monitor the strength development of the epoxy asphalt mixture,a strength test program was employed and then results were compared to those produced from the proposed model.The comparative evaluation shows that a good consistency exists between the outputs from test program and the proposed model,indicating that the proposed model can be used effectively for simulating the curing reaction process for the epoxy asphalt binder and predicting the strength development for the epoxy asphalt mixture.
Directory of Open Access Journals (Sweden)
Andrzej Plewa
Full Text Available The article presents the results of research on the functional properties of asphalt mixes using RAP obtained from milling asphalt road pavements. Asphalt concrete AC 22P with 0%, 10%, 15% and 20% addition of RAP used for base course of road pavements were designed. It was found that asphalt mixes with RAP characterized by comparable and in some cases better functional properties compared to the asphalt mixes without RAP (0%. One should notice the influence of RAP on the performance and durability of the asphalt mixtures, as compared to virgin asphalt mixtures (without RAP.
System-Level Radiation Hardening
Ladbury, Ray
Although system-level radiation hardening can enable the use of high-performance components and enhance the capabilities of a spacecraft, hardening techniques can be costly and can compromise the very performance designers sought from the high-performance components. Moreover, such techniques often result in a complicated design, especially if several complex commercial microcircuits are used, each posing its own hardening challenges. The latter risk is particularly acute for Commercial-Off-The-Shelf components since high-performance parts (e.g. double-data-rate synchronous dynamic random access memories - DDR SDRAMs) may require other high-performance commercial parts (e.g. processors) to support their operation. For these reasons, it is essential that system-level radiation hardening be a coordinated effort, from setting requirements through testing up to and including validation.
Strength Mechanism and Influence Factors for Cold Recycled Asphalt Mixture
Tao Ma; Hao Wang; Yongli Zhao; Xiaoming Huang; Yuhui Pi
This study focused on the key factors affecting the tensile strength of cold recycled asphalt mixture with cement and emulsified asphalt. The specific surface areas and strength of RAP were analyzed. The interaction between the emulsified asphalt and cement was observed. Comprehensive laboratory testing was conducted to evaluate the influences of RAP, emulsified asphalt, and cement on the tensile strength of cold recycled asphalt mixture. It is found that although RAP is used as aggregates, i...
Andrzej Plewa; Marta Wasilewska; Władysław Gardziejczyk; Paweł Gierasimiuk
The article presents the results of research on the functional properties of asphalt mixes using RAP obtained from milling asphalt road pavements. Asphalt concrete AC 22P with 0%, 10%, 15% and 20% addition of RAP used for base course of road pavements were designed. It was found that asphalt mixes with RAP characterized by comparable and in some cases better functional properties compared to the asphalt mixes without RAP (0%). One should notice the influence of RAP on the performance and ...
Fatigue behavior of asphalt mixtures colombian with addition recycled pavement asphalt to 100 %
Directory of Open Access Journals (Sweden)
Neidy Betssey Patiño Boyacá
Full Text Available This research was conducted in order to establish the fatigue behavior of asphalt mixtures with gradations MD20 Instituto de Desarrollo Urbano (IDU and MDC 2 of The Instituto Nacional de Vías (INVIAS, with addition of recycled granular flexible pavement (RAP with asphalt of penetration 60/70 and 80/100. The first step was to characterize the asphalt and RAP as well as calculate the optimum percentage of asphalt to be added to 100 % RAP mixtures. Then samples were fabricated with different trapezoidal gradations and asphalt, to be tested finally fatigue at different deformations. Among the results found, it was determined that the tested mixtures have a high stiffness; although, it varies depending on the asphalt mix used and that the best fatigue life with respect to those studied is the MDC-2 with bitumen 80/100.
Behaviour of asphalt rubber mixtures with different crumb rubber and asphalt binder sources
Fontes, Liseane P. T. L.; Pereira, Paulo A. A.; Pais, Jorge C.; Trichês, Glicério
This study evaluates the performance in laboratory of gap graded mixture prepared with different crumb rubber types and different conventional grade asphalt binders. The asphalt rubbers were prepared via wet process (continuous blend) and their properties were measured through the current tests: (i) penetration;(ii) softening point: (iii) resilience; (iv) apparent viscosity using a Brookfield viscometer. The rheological properties for conventional asphalts were measured too, in order to evalu...
Physical properties of asphalt rubber after being mixed with reclaimed asphalt mixes
Pais, Jorge C.; Pereira, Paulo A. A.; Junior, J.; Gardete, Dinis
Recycling of road pavements became an effective technique after the European legislation defined the amount of reclaimed material that could be sent to landfills. This rehabilitation technique allows the re-use of old pavement material and favours the reduction of the amount of new materials used to produce new pavement layers. One of the most promising pavement rehabilitation techniques uses asphalt rubber mixtures, i.e. asphalt mixtures in which the binder is asphalt modified by crumb r...
Investigating In Situ Properties of Recycled Asphalt Pavement with Foamed Asphalt as Base Stabilizer
Antonis Kaltsounis; Vasilis Papavasiliou; Andreas Loizos; Christina Plati
The objective of the present study was to conduct a comprehensive field experiment for the in situ assessment of in-depth recycled asphalt pavement using foamed asphalt as a stabilization treatment for base works. For this purpose Nondestructive Testing (NDT) data collected using the Falling Weight Deflectometer (FWD) and Ground Penetrating Radar (GPR) along a foamed asphalt recycled pavement section was thoroughly analysed. Critical issues including the stabilized material curing and the con...
Using Pyrolized Carbon Black (PCB) from Waste Tires in Asphalt Pavement (Part 2, Asphalt Binder)
Zeng, Yongdong; Lovell, C. W.
Scrap tires derived from automobiles have become a large environmental problem in the United States. In this study, research is carried out to investigate the potential use of tire-derived pyrolyzed carbon black from scrap tires as an asphalt cement modifier. The asphalt cements used in this research were AC10 and AC20. Penetration and softening point tests were performed to obtain the consistency of the asphalt cements. The pyrolyzed carbon black, as provided by Wolf Industries, was comb...
Radiation-hardenable diluents for radiation-hardenable compositions
International Nuclear Information System (INIS)
Radiation-crosslinkable diluents for radiation-hardenable compositions (binders) consisting of a mixture of triacrylates of a reaction product of trimethylol propane and ethylene oxide with an average degree of ethoxylation of from 2.5 to 4 are described. The ethoxylated trimethylol propane is substantially free from trimethylol propane and has the following distribution: 4 to 5% by weight of monoethoxylation product, 14 to 16% by weight of diethoxylation product, 20 to 30% by weight of triethoxylation product, 20 to 30% by weight of tetraethoxylation product, 16 to 18% by weight of pentaethoxylation product, and 6 to 8% by weight of hexaethoxylation product. The diluents effectively reduce the viscosity of radiation-hardenable compositions and do not have any adverse effect upon their reactivity or upon the properties of the resulting hardened products
Change in fatigue behavior of asphalt hot mixes produced with asphalt rubber binders
Neto, Silvrano Adonias Dantas; Farias, Farias, Márcio Muniz de; Pais, Jorge C.
Fatigue life of asphalt hot mixes is given as a function of both stiffness and tensilestrains induced in the bottom of the wearing courses of flexible pavements. In conventional as-phalt hot mixes the increase of stiffness leads to a decrease of fatigue life. However, this work shows that there is an increase of both fatigue life and stiffness of asphalt rubber hot mixes in comparison with the asphalt hot mixes produced with straight binders. In this work laboratory tests were performed in as...
On the Asphalt Mixture Ratio Design
Institute of Scientific and Technical Information of China (English)
热拌沥青混合料配合比设计关系到沥青砼路面的路用性能。本文结合高速公路沥青路面建设的实际情况,对如何规范操作,以及设计沥青混合料配合比时注意的问题提出了一些建议。%Hot-mix asphalt mixture design is related to the performance of asphalt concrete pavement. This paper, combining with the actual situation of the highway asphalt pavement construction, made recommendations on how to regulate the operation and the problems need pay attention to in design of asphalt mixture.
Method of reprocessing radioactive asphalt solidification products
International Nuclear Information System (INIS)
Purpose: To obtain heat-stable solidification products and decrease the total volume thereof by modifying the solidified form by the reprocessing of existent radioactive asphalt solidification products. Method: Radioactive asphalt solidification products are heated into a fluidized state. Then, incombustible solvents such as perchloroethylene or trichloroethylene are added to a dissolving tank to gradually dissolve the radioactive asphalt solidification products. Thus, organic materials such as asphalts are transferred into the solvent layer, while inorganic materials containing radioactive materials remain as they are in the separation tank. Then, the inorganic materials containing the radioactive materials are taken out and then solidified, for example, by converting them into a rock or glass form. (Kawakami, Y.)
Linking asphalt binder fatigue to asphalt mixture fatigue performance using viscoelastic continuum damage modeling
Safaei, Farinaz; Castorena, Cassie; Kim, Y. Richard
Fatigue cracking is a major form of distress in asphalt pavements. Asphalt binder is the weakest asphalt concrete constituent and, thus, plays a critical role in determining the fatigue resistance of pavements. Therefore, the ability to characterize and model the inherent fatigue performance of an asphalt binder is a necessary first step to design mixtures and pavements that are not susceptible to premature fatigue failure. The simplified viscoelastic continuum damage (S-VECD) model has been used successfully by researchers to predict the damage evolution in asphalt mixtures for various traffic and climatic conditions using limited uniaxial test data. In this study, the S-VECD model, developed for asphalt mixtures, is adapted for asphalt binders tested under cyclic torsion in a dynamic shear rheometer. Derivation of the model framework is presented. The model is verified by producing damage characteristic curves that are both temperature- and loading history-independent based on time sweep tests, given that the effects of plasticity and adhesion loss on the material behavior are minimal. The applicability of the S-VECD model to the accelerated loading that is inherent of the linear amplitude sweep test is demonstrated, which reveals reasonable performance predictions, but with some loss in accuracy compared to time sweep tests due to the confounding effects of nonlinearity imposed by the high strain amplitudes included in the test. The asphalt binder S-VECD model is validated through comparisons to asphalt mixture S-VECD model results derived from cyclic direct tension tests and Accelerated Loading Facility performance tests. The results demonstrate good agreement between the asphalt binder and mixture test results and pavement performance, indicating that the developed model framework is able to capture the asphalt binder's contribution to mixture fatigue and pavement fatigue cracking performance.
Linking asphalt binder fatigue to asphalt mixture fatigue performance using viscoelastic continuum damage modeling
Safaei, Farinaz; Castorena, Cassie; Kim, Y. Richard
Fatigue cracking is a major form of distress in asphalt pavements. Asphalt binder is the weakest asphalt concrete constituent and, thus, plays a critical role in determining the fatigue resistance of pavements. Therefore, the ability to characterize and model the inherent fatigue performance of an asphalt binder is a necessary first step to design mixtures and pavements that are not susceptible to premature fatigue failure. The simplified viscoelastic continuum damage (S-VECD) model has been used successfully by researchers to predict the damage evolution in asphalt mixtures for various traffic and climatic conditions using limited uniaxial test data. In this study, the S-VECD model, developed for asphalt mixtures, is adapted for asphalt binders tested under cyclic torsion in a dynamic shear rheometer. Derivation of the model framework is presented. The model is verified by producing damage characteristic curves that are both temperature- and loading history-independent based on time sweep tests, given that the effects of plasticity and adhesion loss on the material behavior are minimal. The applicability of the S-VECD model to the accelerated loading that is inherent of the linear amplitude sweep test is demonstrated, which reveals reasonable performance predictions, but with some loss in accuracy compared to time sweep tests due to the confounding effects of nonlinearity imposed by the high strain amplitudes included in the test. The asphalt binder S-VECD model is validated through comparisons to asphalt mixture S-VECD model results derived from cyclic direct tension tests and Accelerated Loading Facility performance tests. The results demonstrate good agreement between the asphalt binder and mixture test results and pavement performance, indicating that the developed model framework is able to capture the asphalt binder's contribution to mixture fatigue and pavement fatigue cracking performance.
Zhukov, P.; Kravchuk, Y.; Zhukov, D.
The development of transport infrastructure, which must conform to European standards and in its turn requires the development of road economy, is one of the ways out of the crisis. The development of road economy requires either construction of asphalt-concrete mixture plants or their modernization, or reconstruction of existing plants. Any reconstruction or modernization and, moreover, construction of new asphalt-concrete plants requires the optimization of choosing the most efficient aspha...
Performance Characteristics of Silane Silica Modified Asphalt
Xuedong Guo; Mingzhi Sun; Wenting Dai; Shuang Chen
At present there are many kinds of fillers and modifier used for modified asphalt, but the effect of modifier differs in thousands of ways; most of them can increase the high temperature performance of asphalt, but the modified effect of low-temperature crack resistance, water stability, and antifatigue performance is different. Aiming at the subsistent problems, this paper innovatively puts forward the idea of taking the silane silica (nanosilica modified with silane coupling agent) as fille...
Safety evaluation of asphalt products, (1)
International Nuclear Information System (INIS)
The safety of activity-containing asphalt products kept in enclosed storage was evaluated from considerations of radiolysis and hydrogen evolution. The samples examined were mainly homogeneous asphalt products containing 43w/0 of sludge produced in routine operation of the asphalt plant at the Japan Atomic Energy Research Institute (JAERI), the samples were irradiated with external 60Co γ-ray source to a dose of 109 R. The bulk of the gases evolving from the asphalt product is hydrogen, which constitutes 75 -- 95% of the total gas evolution. The total amount of gases generated during infinite time is proportional to the total exposure dose; hydrogen evolves at a rate of 5.5x10-3 cm3/g.MR. The amount of total gas evolution is governed solely by the quantity of asphalt, and is independent of the sludge contained therein. Nor do differences in the rate of dose appear to have any significant effect. In so far as concerns smallness of radiolysis, slightly better performance can be expected from straight than from blown asphalt. There is no danger of explosion of the asphalt products currently generated at JAERI (10-5 Ci/kg), which can be expected to accumulate in infinite time no more than about 3 cm3 from a 200 l product. Only asphalt products containing activity in concentrations exceeding 10-1 Ci/kg risk explosion when kept in enclosed storage, through accumulation of hydrogen in quantity exceeding the explosion limit in a relatively short time. (auth.)
Asphalt mixtures produced with 100% reclaimed materials
Oliveira, Joel; Silva, Hugo Manuel Ribeiro Dias da; Jesus, Carlos M. G.
The environmental and economic benefits of using Reclaimed Asphalt Pavement (RAP) material in hot mix asphalt (HMA) applications could be pushed up to the limit, by producing totally recycled HMAs (100% RAP), but the performance of this alternative must be satisfactory. In fact, these mixtures could possibly present a lower performance due to the behaviour of the aged binder, which loses its lighter fractions with time. In order to improve the mixture properties, a binder rejuvenator should b...
Rapid determination of actinides in asphalt samples
International Nuclear Information System (INIS)
A new rapid method for the determination of actinides in asphalt samples has been developed that can be used in emergency response situations or for routine analysis. If a radiological dispersive device, improvised nuclear device or a nuclear accident such as the accident at the Fukushima Nuclear Power Plant in March, 2011 occurs, there will be an urgent need for rapid analyses of many different environmental matrices, including asphalt materials, to support dose mitigation and environmental clean-up. The new method for the determination of actinides in asphalt utilizes a rapid furnace step to destroy bitumen and organics present in the asphalt and sodium hydroxide fusion to digest the remaining sample. Sample preconcentration steps are used to collect the actinides and a new stacked TRU Resin + DGA Resin column method is employed to separate the actinide isotopes in the asphalt samples. The TRU Resin plus DGA Resin separation approach, which allows sequential separation of plutonium, uranium, americium and curium isotopes in asphalt samples, can be applied to soil samples as well. (author)
Rheological properties of asphalts with particulate additives
Energy Technology Data Exchange (ETDEWEB)
Shashidhar, N. [EBA Engineering, Baltimore, MD (United States); Chollar, B.H. [Federal Highway Administration, McLean, VA (United States)
The Superpave asphalt binder specifications are performance-based specifications for purchasing asphalt binders for the construction of roads. This means that the asphalt is characterized by fundamental material (rheological) properties that relate to the distress modes of the pavements. The distress modes addressed are primarily rutting, fatigue cracking and low temperature cracking. For example, G*/sin({delta}) is designed to predict the rutting potential of pavements, where G* is the magnitude of the complex shear modulus and 6 is the phase angle. The binder for a road that is situated in a certain climatic zone requires the binder to have a minimum G*/sin({delta}) of 2200 Pa at the highest consecutive 7-day average pavement temperature the road had experienced. Implicit in such a performance based specification is that the fundamental property, G*/sin({delta}), of the binder correlates with rutting potential of the pavement regardless of the nature of the binder. In other words, the specification is transparent to the fact that the binder can simply be an asphalt, or an asphalt modified by polymers, particulates and other materials that can form a two-phase mixture. This paper discusses the asphalt-particulate system.
Study on Producing Heavy Paving Asphalt
Institute of Scientific and Technical Information of China (English)
Liu Daosheng; Gao Zhirong; Huo Kaifu; Liao Kejian
The highly viscous crude oil from Shuguang No. 1 zone of Liaohe oilfield features high density,high viscosity and low wax content. It contains no gasoline fraction and its diesel oil fraction yield is only 7.19%, which belongs to the low sulfur naphthenic stocks crude oil. Its heavy fraction is not suited for producing lubricating oil. Its heavy oil, which contains more resins and asphaltenes and less wax, is not an ideal feedstock for catalytic cracking, but is the ideal raw material for producing high-grade paving asphalt.Now this highly viscous crude oil is used as fuel oil after being emulsified in Liaohe oilfield, but its viscosity is so high that it cannot be atomized uniformly and burned completely, resulting not only in waste of oil resource but also in reduction of economical benefit. To make full use of this oil resource and alleviate the shortfall of high grade paving asphalt in China, various brands of asphalt meeting Q/SHR003-1998and ESSO specifications were developed by blending vacuum residue of the said oil and a blending component which are rich in aromatics and deficient in wax. The impact of blending component on properties of blended asphalt has been investigated and road performances of these blended asphalts were studied. The laboratory test results show that the blended asphalts have good road performance and antiaging property.
Asphalt wear and pollution transport
Energy Technology Data Exchange (ETDEWEB)
Lindgren, Asa [Division of Traffic Engineering, Lulea University of Technology Lulea (Sweden)
Studded tires cause extensive wear of road surfaces during winter producing small particles. Besides transporting different adsorbed pollutants these particles also discharge metal ions by their own natural content. The major part (95%) of the asphalt is composed of stone fractions. The rest consists mainly of bitumen, which contains trace quantities of metals. Laboratory studies in this study have demonstrated different adsorbing properties of metal ions, as well as differences in adsorption when comparing stone materials. Two stone materials, a gabbro and a porphyry, have been tested for their adsorption properties concerning Pb, Cu, Zn and Cd. The gabbro showed better adsorption capacity than the porphyry. Gabbro has coarser grains, it is softer, and also has a higher content of most metals compared to the porphyry. In all tests lead and copper are more adsorbed than zinc and cadmium. All metal ions are released at about the same pH ({approx}4)
Effects of reclaimed asphalt pavement on indirect tensile strength test of conditioned foamed asphalt mix
International Nuclear Information System (INIS)
This paper presents the results of Indirect Tensile Strength (ITS) Test for samples prepared with reclaimed asphalt pavement (RAP). Samples were conditioned in water at 25°C for 24 hours prior to testing. Results show that recycled aggregate from reclaimed asphalt pavement performs as well as virgin aggregate.
Effects of reclaimed asphalt pavement on indirect tensile strength test of conditioned foamed asphalt mix
Yati Katman, Herda; Rasdan Ibrahim, Mohd; Yazip Matori, Mohd; Norhisham, Shuhairy; Ismail, Norlela
This paper presents the results of Indirect Tensile Strength (ITS) Test for samples prepared with reclaimed asphalt pavement (RAP). Samples were conditioned in water at 25°C for 24 hours prior to testing. Results show that recycled aggregate from reclaimed asphalt pavement performs as well as virgin aggregate.
Onycholysis induced by nail hardener.
Helsing, Per; Austad, Joar; Talberg, Hans Jørgen
Nail hardeners appeared in the market during the 1960s. They were basically solutions of formaldehyde. The first adverse effects were published in 1966 (1). Reactions were onycholysis, chromonychia, subungual haemorrhage, and hyperkeratosis. Onycholysis may be non-inflammatory or inflammatory, and is accompanied by throbbing pain. Inflammatory reactions are followed by paronychia and occasional dermatitis on the digital pulpa. PMID:17868227
Foley, S.
The Burnett Archive of Working Class Autobiographies was gathered together by John Burnett, David Vincent and David Mayall whilst compiling their three volumes annotated bibliography, "The Autobiography of the Working Class" (Harvester Press, 1984-1989). This book includes descriptions of unpublished autobiographies and indicates their locations. Excerpts from some of the autobiographies have been published in "Destiny obscure: autobiographies of childhood, education, and family from the1820s...
Institute of Scientific and Technical Information of China (English)
The mechanical properties and durability ( mainly frost-resistance and carbonation resistance ) of fly ash-CaO-CaSO4 .2H2O hardened paste are studied. The relationship among durability of harden ed fly ash paste, the quantity and distribution of hydrates and the initial p aste texture of hardened fly ash paste is presented.
Experimental studies of biodegradation of asphalt by microorganisms
International Nuclear Information System (INIS)
On the geological disposal system of the radioactive wastes, the activities of the microorganisms that could degrade the asphalt might be significant for the assessment of the system performance. As the main effects of the biodegradation of the asphalt, the fluctuation of leaching behavior of the nuclides included in asphalt waste has been indicated. In this study, the asphalt biodegradation test was carried out. The microorganism of which asphalt degradation ability was comparatively higher under aerobic condition and anaerobic condition was used. The asphalt biodegradation rate was calculated and it was evaluated whether the asphalt biodegradation in this system could occur. The results show that the asphalt biodegradation rate under anaerobic and high alkali condition will be 300 times lower than under aerobic and neutral pH. (author)
Zolotarev, V.; Golovenchic, S.; Oksak, S.; S. Efremov
The possibility of receiving of color asphalt concrete on polimer-tar binder is found. Principal moments of production technology of coloured mixtures and device of asphalt concrete coating have been revealed.
Theoretic computing model of combustion process of asphalt smoke
Institute of Scientific and Technical Information of China (English)
HUANG Rui; CHAI Li-yuan; HE De-wen; PENG Bing; WANG Yun-yan
Based on the data and methods provided by research literature, dispersing mathematical model of combustion process of asphalt smoke is set by theoretic analysis. Through computer programming, the dynamic combustion process of asphalt smoke is calculated to simulate an experimental model. The computing result shows that the temperature and the concentration of asphalt smoke influence its burning temperature in approximatively linear manner. The consumed quantity of fuel to ignite the asphalt smoke needs to be measured from the two factors.
Effects of preparation process on performance of rubber modified asphalt
Liu, Hanbing; Luo, Guobao; Wang, Xianqiang; Jiao, Yubo
The rational utilization of waste rubber tire is essential for the environmental protection. Utilizing rubber particles to modify asphalt can not only improve asphalt performance, but also help the recycling of waste materials. Considering the effect of different preparation process parameters on the performance of rubber modified asphalt, this paper analyzes the effects of the shear temperature, shear time and shear rate on the performance of rubber modified asphalt, and provided a reference for its preparation.
Reinforcing Effects of Carbon Black on Asphalt Binder for Pavement
Yamaguchi, Katsuyuki; Sasaki, Iwao; Nishizaki, Itaru; Meiarashi, Seishi; Moriyoshi, Akihiro
Carbon black, used as a reinforcing filler for rubber materials, was evaluated for asphalt binders in pavements. Carbon black added to straight asphalt within 20 wt% caused an increase in the elastic modulus and a decrease in the viscosity of the asphalt, especially at temperatures higher than room temperature. Addition of carbon black raised the maximum service temperature of asphalt in the category of the binder performance grade according to the SHRP (Strategic Highway Research Program) sp...
Influence of crumb rubber gradation on asphalt-rubber properties
Neto, Silvrano Adonias Dantas; Farias, Márcio Muniz de; Pais, Jorge C.; Pereira, Paulo A. A.
Asphalt rubber is a material produced by the incorporation of crumb rubber obtained from ground tires in straight asphalt and its properties are influenced by the components properties. The crumb rubber gradation is one of the variables which have a significant influence on asphalt rubber properties. Thus, this work studies the influence of crumb rubber gradation on the asphalt rubber properties expressed by penetration, rotational viscosity (using the Brookfield viscometer), r...
Surface roughness of an asphalt concrete and its mechanical behavior
MOMM, L; DE LA ROCHE, C; Domingues, A.
The surface roughness of asphalt concrete is studied according to the maximum aggregate size and to the equation of the aggregate graduation curve, on asphalt concrete plates made in laboratory. The macrotexture increases when the maximum aggregate size increases and it decreases when the aggregate fine contents increases. The asphalt concrete structural behaviour is evaluated with rutting, complex modulus and fatigue tests. The study shows stronger mechanical performances on the asphalt conc...
Biodegradation of Asphalt Cement-20 by Aerobic Bacteria
Pendrys, John P.
Seven gram-negative, aerobic bacteria were isolated from a mixed culture enriched for asphalt-degrading bacteria. The predominant genera of these isolates were Pseudomonas, Acinetobacter, Alcaligenes, Flavimonas, and Flavobacterium. The mixed culture preferentially degraded the saturate and naphthene aromatic fractions of asphalt cement-20. A residue remained on the surface which was resistant to biodegradation and protected the underlying asphalt from biodegradation. The most potent asphalt-...
Modification of Asphalt by the Use of Crumb Rubber
Shah Room; Muhammad Aleem; Muhammad Ahmad Rana; Umair Anwar Awan; Sajjad Ali
Health aspects enforced to ponder a study on asphalt which incorporate rubber crumbs to increase strength and flexibility of asphalt. Disposal of waste tires is a menace and it's a serious problem globally because it is not easily biodegradable as these tires consume large spaces, open burning cause serious problems. By the use of rubber tires, this scrap is utilized efficiently and reduces the cost of asphalt to produce economical system. The asphalt is absorbed by the rubber par...
Laboratory mix design of asphalt mixture containing reclaimed material
Davide Lo Presti; Rawid Khan; Norhidayah Abdul Hassan; Gordon Airey; Andrew Collop
This paper presents a study on the production of asphalt test specimens in the laboratory containing reclaimed asphalt. The mixtures considered were stone mastic asphalt concrete mixtures containing up to 30% of reclaimed asphalt. Specimens were compacted to the reference density obtained from the Marshall mix design. Gyration compaction method was used for preparing specimens for the experimental programme, while coring and cutting methods and X-ray computed tomography (CT) were used to inve...
Full-Depth Asphalt Pavements for Parking Lots and Driveways.
Asphalt Inst., College Park, MD.
The latest information for designing full-depth asphalt pavements for parking lots and driveways is covered in relationship to the continued increase in vehicle registration. It is based on The Asphalt Institute's Thickness Design Manual, Series No. 1 (MS-1), Seventh Edition, which covers all aspects of asphalt pavement thickness design in detail,…
40 CFR 52.2054 - Control of asphalt paving material.
... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Control of asphalt paving material. 52... asphalt paving material. (a) Notwithstanding any provisions to the contrary in the Pennsylvania Implementation Plan, the Pennsylvania Department of Transportation shall restrict the annual usage of asphalts...
Radiation-hardened bulk CMOS technology
International Nuclear Information System (INIS)
The evolutionary development of a radiation-hardened bulk CMOS technology is reviewed. The metal gate hardened CMOS status is summarized, including both radiation and reliability data. The development of a radiation-hardened bulk silicon gate process which was successfully implemented to a commercial microprocessor family and applied to a new, radiation-hardened, LSI standard cell family is also discussed. The cell family is reviewed and preliminary characterization data is presented. Finally, a brief comparison of the various radiation-hardened technologies with regard to performance, reliability, and availability is made
Multiscale Constitutive Modeling of Asphalt Concrete
Underwood, Benjamin Shane
Multiscale modeling of asphalt concrete has become a popular technique for gaining improved insight into the physical mechanisms that affect the material's behavior and ultimately its performance. This type of modeling considers asphalt concrete, not as a homogeneous mass, but rather as an assemblage of materials at different characteristic length scales. For proper modeling these characteristic scales should be functionally definable and should have known properties. Thus far, research in this area has not focused significant attention on functionally defining what the characteristic scales within asphalt concrete should be. Instead, many have made assumptions on the characteristic scales and even the characteristic behaviors of these scales with little to no support. This research addresses these shortcomings by directly evaluating the microstructure of the material and uses these results to create materials of different characteristic length scales as they exist within the asphalt concrete mixture. The objectives of this work are to; 1) develop mechanistic models for the linear viscoelastic (LVE) and damage behaviors in asphalt concrete at different length scales and 2) develop a mechanistic, mechanistic/empirical, or phenomenological formulation to link the different length scales into a model capable of predicting the effects of microstructural changes on the linear viscoelastic behaviors of asphalt concrete mixture, e.g., a microstructure association model for asphalt concrete mixture. Through the microstructural study it is found that asphalt concrete mixture can be considered as a build-up of three different phases; asphalt mastic, fine aggregate matrix (FAM), and finally the coarse aggregate particles. The asphalt mastic is found to exist as a homogenous material throughout the mixture and FAM, and the filler content within this material is consistent with the volumetric averaged concentration, which can be calculated from the job mix formula. It is also
Design and Performance of Hot Mix Asphalts with High Percentages of Reclaimed Asphalt: Approach followed in the Paramix Project
Pérez, F; Rodriguez, M.; De Visscher, J.; Vanelstraete, A.; Bock, L.
The use of reclaimed asphalt pavement (RA) in new asphalt pavements can provide important economical savings, while reducing the negative environmental impact. The European research project PARAMIX aims to improve the techniques for hot mix recycling in plant and cold mix in situ recycling, so as to increase the amount of reclaimed asphalt and develop competitive road pavement rehabilitation techniques. This paper deals with the design of hot mix asphalts for the project. The di...
Analysing polystyrene-modified asphalt and its incidence in a heat-dense asphalt mixture
Directory of Open Access Journals (Sweden)
Ana Sofía Figueroa Infante
Full Text Available This article presents some results obtained with an MDC-2 asphalt/polystyrene-modified asphalt mixture as a result of crushing waste glass. The stone, asphalt and polystyrene materials' were characterised for drawing up the design. The Marshal method was used for obtaining the best asphalt- stone-polystyrene percentages. The Superpave method was used for analysing the asphalt; the mixture's dynamic behaviour was analysed using a test involving 20ºC and 30ºC trapezoidal fatigue for 90x10-6, 150x10-6 and 220x10-6m deformation. The truck-wheel test was analysed for a 13-ton load, similar to that of the heaviest axle on a Transmilenio (articulated bus. The dynamic module test was analysed for 15ºC, 20ºC and 30ºC and 2.5, 5 and 10 Hz frequencies. Conventional asphalt mixture and modified asphalt results were contrasted, interesting behaviour being observed regarding plastic deformation of the modified mixture in service
Surface Fatigue Resistance with Induction Hardening
Townsend, Dennis; Turza, Alan; Chapman, Mike
Induction hardening has been used for some years to harden the surface and improve the strength and service life of gears and other components. Many applications that employ induction hardening require a relatively long time to finish the hardening process and controlling the hardness of the surface layer and its depth often was a problem. Other surface hardening methods, ie., carbonizing, take a very long time and tend to cause deformations of the toothing, whose elimination requires supplementary finishing work. In double-frequency induction hardening, one uses a low frequency for the preheating of the toothed wheel and a much higher frequency for the purpose of rapidly heating the surface by way of surface hardening.
Mechanical Response Analysis of Asphalt Pavement Structure
Directory of Open Access Journals (Sweden)
Yu Zhenqing
Full Text Available Generally, the Chinese designed life of the high- grade asphalt concrete pavement is required 15 years, however, the designed life of the road in surface is often lower than the designed life, and even premature failure. Especially in heavy traffic conditions, the early damage of some high grade-asphalt pavement in China is serious. According to some investigations, we founded the main reason of the long-life asphalt pavement is to determine the function of each structure layer. According to the stress of pavement structure layer, so as to select the structure layer materials. Based on the viewpoint of mechanics, asphalt pavement damage mode is divided into three categories, such as top-down crack, fatigue cracking and rutting. Therefore, this paper uses ANSYS finite element software as calculation tool, the combination of road vehicle load and the primary influence on asphalt pavement structure mechanics response characteristics were analyzed. In this paper, the method of analysis is control variable: that means under different vehicle axle load, only change surface layer modulus and observe the pavement structure mechanical response trends to compare the effect. By using the same method, the response of the pavement base course parameters to the pavement mechanical structure is analyzed.
High Modulus Asphalt Concrete with Dolomite Aggregates
Haritonovs, V.; Tihonovs, J.; Smirnovs, J.
Dolomite is one of the most widely available sedimentary rocks in the territory of Latvia. Dolomite quarries contain about 1,000 million tons of this material. However, according to Latvian Road Specifications, this dolomite cannot be used for average and high intensity roads because of its low quality, mainly, its LA index (The Los Angeles abrasion test). Therefore, mostly the imported magmatic rocks (granite, diabase, gabbro, basalt) or imported dolomite are used, which makes asphalt expensive. However, practical experience shows that even with these high quality materials roads exhibit rutting, fatigue, and thermal cracks. The aim of the research is to develop a high performance asphalt concrete for base and binder courses using only locally available aggregates. In order to achieve resistance against deformations at a high ambient temperature, a hard grade binder was used. Workability, fatigue and thermal cracking resistance, as well as sufficient water resistance is achieved by low porosity (3-5%) and higher binder content compared to traditional asphalt mixtures. The design of the asphalt includes a combination of empirical and performance based tests, which in laboratory circumstances allow simulating traffic and environmental loads. High performance AC 16 base asphalt concrete was created using local dolomite aggregate with polymer modified (PMB 10/40-65) and hard grade (B20/30) bitumen. The mixtures were specified based on fundamental properties in accordance with EN 13108-1 standard.
Current practices for modification of paving asphalts
Energy Technology Data Exchange (ETDEWEB)
Bahia, H.U.; Perdomo, D. [Asphalt Institute, Lexington, KY (United States)
The Superpave binder specification, AASHTO MP1, has introduced new concepts for selecting paving asphalt binders. The specification, in addition to using rheological and failure measurements that are more related to performance, is based on the idea that the criteria to maintain a satisfactory contribution of asphalt binders to the resistance of pavement failures remains the same but have to be satisfied at critical application temperatures. The test procedures require that the material be characterized within certain ranges of strains or stresses to ensure that material and geometric non-linearities are not confounded in the measurements. These new specification concepts have resulted in re-evaluation of asphalt modification by the majority of modified asphalt suppliers. The philosophy of asphalt modification is expected to change, following these new concepts, from a general improvement of quality to more focus on using modifiers based on the most critical need as defined by two factors: (1) The application temperature domain and (2) the type of distress to be remedied. The new specification requirements should result in a more effective use of modifiers as the amount and type of modifier will be directly related to the application environment and the engineering requirements.
Energetic model of metal hardening
Directory of Open Access Journals (Sweden)
Ignatova O.N.
Full Text Available Based on Bailey hypothesis on the link between strain hardening and elastic lattice defect energy this paper suggests a shear strength energetic model that takes into consideration plastic strain intensity and rate as well as softening related to temperature annealing and dislocation annihilation. Metal strain hardening was demonstrated to be determined only by elastic strain energy related to the energy of accumulated defects. It is anticipated that accumulation of the elastic energy of defects is governed by plastic work. The suggested model has a reasonable agreement with the available experimental data for copper up to P = 70 GPa , for aluminum up to P = 10 GPa and for tantalum up to P = 20 GPa.
Scintillation-Hardened GPS Receiver
Stephens, Donald R.
CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.
Radiation-hardened control system
International Nuclear Information System (INIS)
A radiation-hardened bit-slice control system with associated input/output circuits was developed to prove that programmable circuits could be constructed to successfully implement intelligent functions in a highly radioactive environment. The goal for this effort was to design and test a programmable control system that could withstand a minimum total dose of 107 rads (gamma). The Radiation Hardened Control System (RHCS) was tested in operation at a dose rate that ranged up to 135 krad/h, with an average total dose of 10.75 Mrads. Further testing beyond the required 107 rads was also conducted. RHCS performed properly through the target dose of 107 rads, and sporadic intermittent failures in some programmable logic devices were noted after ∼ 13 Mrads
Ethanol based foamed asphalt as potential alternative for low emission asphalt technology
Directory of Open Access Journals (Sweden)
Mohd Rosli Mohd Hasan
Full Text Available Foamed asphalt typically relies on water as a foaming agent because water becomes gaseous at elevated temperatures, generating numerous tiny bubbles in the asphalt and causing spontaneous foaming. In this study, ethanol was used as a potential alternative to water as a foaming agent. Ethanol is expected to be a physical blowing agent in the same manner as water, except it requires less energy to foam due to its 78 °C boiling point. This study compares the performance of water and ethanol as foaming agents through the measurements of rotational viscosity, the reduction in temperature during foaming, and volatile loss. The ethanol-foamed asphalt binders were prepared at 80 °C and 100 °C, while the water-foamed asphalt binders were prepared at 100 °C and 120 °C. Additionally, the rolling thin film oven (RTFO was used to generate short-term aging of the foamed asphalt binders. A rotational viscometer was used to determine the viscosity of the asphalt binders at 80 °C, 100 °C, 120 °C, 140 °C, and 160 °C. Overall, ethanol can function in the same manner as water but requires less energy to foam. It is proven based on the smaller drop in temperature of the asphalt binder foamed using ethanol compared with that prepared with water. This is due to the lower latent heat capacity of ethanol, which requires less energy to vaporize compared with water. Through the rotational viscometer test, ethanol performs better in lowering the viscosity of asphalt binders, which is essential in allowing production processes at low temperatures, as well as a better workability and aggregate coating. Ethanol can be expelled from the foamed asphalt binders at a higher rate due to its lower boiling point and latent heat.
Research on Alkaline Filler Flame-Retarded Asphalt Pavement
Institute of Scientific and Technical Information of China (English)
HU Shuguang; ZHANG Houji; WANG Jiaolan
Used as flame retardant of tunnel asphalt pavement, organic bromides produce a large amount of poisons and smoke in construction and flame retardation stage. The alkaline filler was found to replace mineral filler, and the flame-retarded asphalt mixtures were produced. Experimental results show that these asphalt mixtures are smoke restrained; the performances and construction technology of asphalt pavement are not influenced; also the alkaline filler is of low-price. So this kind of flame-retarded asphalt mixtures is suitable for tunnel pavement.
Pitch-asphalts - new binder for road construction
Energy Technology Data Exchange (ETDEWEB)
Stompel, Z.; Collin, G.; Szen, A.; Herion, G.
Discusses chemical and physical properties of a mixture of pitches and asphalts produced by the Blachownia Chemical Plant. The mixture consists of coal tar pitches with 25.7% content of toluene-insoluble fractions, anthracene oil and Dex asphalt. The following properties were analyzed: density, softening and softening point, adhesion, viscosity, sedimentation after 14 days. Physical and chemical properties of the pitch-asphalt from Blachownia were compared to those of pitch-asphalt from Ruetgerswerke AG in the FRG. Pitch-asphalt properties were evaluated from the point of view of their use in road construction. 8 refs.
Simulation of rheological behavior of asphalt mixture with lattice model
Institute of Scientific and Technical Information of China (English)
杨圣枫; 杨新华; 陈传尧
A three-dimensional(3D) lattice model for predicting the rheological behavior of asphalt mixtures was presented.In this model asphalt mixtures were described as a two-phase composite material consisting of asphalt sand and coarse aggregates distributed randomly.Asphalt sand was regarded as a viscoelastic material and aggregates as an elastic material.The rheological response of asphalt mixture subjected to different constant stresses was simulated.The calibrated overall creep strain shows a good approximation to experimental results.
Application of retardation time spectra of asphalt
Institute of Scientific and Technical Information of China (English)
ZHAN Xiao-li; ZHANG Xiao-ning; LU Liang
To improve the performance of asphah pavement,the dynamic and static tests of asphalt were used to measure its viscoelastic properties under different time.Based on the obtained data of static creep compliances and dynamic compliances according to the static creep test and dynamic test of asphalt using the dynamic shear rheometer,the discrete retardation time spectra were attained using the non-linear regression method.All viseoelastic functions are mathematically equivalent and belong to the same retardation time spectra,so the dynamic compliances of asphalt were converted to the static creep compliance using the retardation time spectra.Good correlations were found betwin calculation results and measurement results.In accordalice to these findings,the retardation time spectra can accurately transform static and dynamic viscoelastic functions.Therefore,we can obtain viscoelastic properties over much larger time or frequency region than measurement results.
Asphalt rubber mixtures in Portugal: fatigue resistance
Miranda, Henrique; Batista, Fátima; Neves, José; Antunes, Maria de Lurdes; Fonseca, Paulo
This paper presents a study concerning the fatigue behaviour of asphalt mixtures with bitumen modified with high content of crumb rubber used in Portugal. For assessing the fatigue behaviour of this type of mixtures, four asphalt mixtures with high content of crumb rubber were used: two field bituminous mixtures – an open-graded and a gap-graded – both with granite aggregates; and two laboratory manufactured bituminous mixtures – an open-graded mixture with granite aggregates and a gap-graded...
Investigating In Situ Properties of Recycled Asphalt Pavement with Foamed Asphalt as Base Stabilizer
Directory of Open Access Journals (Sweden)
Christina Plati
Full Text Available The objective of the present study was to conduct a comprehensive field experiment for the in situ assessment of in-depth recycled asphalt pavement using foamed asphalt as a stabilization treatment for base works. For this purpose Nondestructive Testing (NDT data collected using the Falling Weight Deflectometer (FWD and Ground Penetrating Radar (GPR along a foamed asphalt recycled pavement section was thoroughly analysed. Critical issues including the stabilized material curing and the contribution of the asphalt layers to the structural properties of the in-depth recycled pavement are discussed. In addition, recommendations concerning the improvement of the structural condition of the in-depth recycled pavement are developed based on this practical approach of investigation using NDT.
Performance Evaluation of Stone Mastic Asphalt and Hot Mix Asphalt Mixtures Containing Recycled Concrete Aggregate
Directory of Open Access Journals (Sweden)
Mohammad Saeed Pourtahmasb
Full Text Available Environmental and economic considerations have encouraged civil engineers to find ways to reuse recycled materials in new constructions. The current paper presents an experimental research on the possibility of utilizing recycled concrete aggregates (RCA in stone mastic asphalt (SMA and hot mix asphalt (HMA mixtures. Three categories of RCA in various percentages were mixed with virgin granite aggregates to produce SMA and HMA specimens. The obtained results indicated that, regardless of the RCA particular sizes, the use of RCA to replace virgin aggregates increased the needed binder content in the asphalt mixtures. Moreover, it was found that even though the volumetric and mechanical properties of the asphalt mixtures are highly affected by the sizes and percentages of the RCA but, based on the demands of the project and traffic volume, utilizing specific amounts of RCA in both types of mixtures could easily satisfy the standard requirements.
Comparison of laboratory test performance between asphalt-rubber hot mix and dense graded asphalt concrete
Sousa, Jorge B.; Pais, Jorge C.; Stubstad, Richard N.
"Reflective cracking in pavements : research in practice" contains the Proceedings of the 4th International RILEM Conference on Reflective Cracking in Pavements (Proceedings PRO11). Asphalt-Rubber Hot-Mix (ARHM) has shown a higher resistance to flexural and reflective fatigue cracking, and also to permanent deformation, than conventional Dense Graded Asphalt Concrete (DGAC). Experience has demonstrated that with ARHM, a significant reduction in overlay thickness is possible, especially in...
Performance Evaluation of Stone Mastic Asphalt and Hot Mix Asphalt Mixtures Containing Recycled Concrete Aggregate
Mohammad Saeed Pourtahmasb; Mohamed Rehan Karim
Environmental and economic considerations have encouraged civil engineers to find ways to reuse recycled materials in new constructions. The current paper presents an experimental research on the possibility of utilizing recycled concrete aggregates (RCA) in stone mastic asphalt (SMA) and hot mix asphalt (HMA) mixtures. Three categories of RCA in various percentages were mixed with virgin granite aggregates to produce SMA and HMA specimens. The obtained results indicated that, regardless of t...
Advanced methodology for optimization of mixture design of asphalt concrete containing reclaimed asphalt pavement material
Bressi, Sara
Despite the massive use of Reclaimed Asphalt Pavement (RAP) in Hot Mix Asphalt (HMA) production, the chemo-physical phenomena that characterise the fabrication of these mixtures have not yet been completely explored. The detection and understanding of these mechanisms as well as the study of the heterogeneity that characterizes high RAP mix production are fundamental to improving the approach to recycling, because they represent the source of the mixture characteristics and performance. This...
Evaluation of Warm Mix Asphalt Additives for Use in Modified Asphalt Mixtures
Chamoun, Zahi
The objective of this research effort is to evaluate the use of warm-mix additives with polymer modified and terminal blend tire rubber asphalt mixtures from Nevada and California. The research completed over two stages: first stage evaluated two different WMA technologies; Sasobit and Advera, and second stage evaluated one additional WMA technology; Evotherm. The experimental program covered the evaluation of resistance of the mixtures to moisture damage, the performance characteristics of the mixtures, and mechanistic analysis of mixtures in simulated pavements. In the both stages, the mixture resistance to moisture damage was evaluated using the indirect tensile test and the dynamic modulus at multiple freeze-thaw cycles, and the resistance of the various asphalt mixtures to permanent deformation using the Asphalt Mixture Performance Tester (AMPT). Resistance of the untreated mixes to fatigue cracking using the flexural beam fatigue was only completed for the first stage. One source of aggregates was sampled in, two different batches, three warm mix asphalt technologies (Advera, Sasobit and Evotherm) and three asphalt binder types (neat, polymer-modified, and terminal blend tire rubber modified asphalt binders) typically used in Nevada and California were evaluated in this study. This thesis presents the resistance of the first stage mixtures to permanent deformation and fatigue cracking using two warm-mix additives; Advera and Sasobit, and the resistance to moisture damage and permanent deformation of the second stage mixtures with only one warm-mix additive; Evotherm.
Microstructural Analysis and Rheological Modeling of Asphalt Mixtures Containing Recycled Asphalt Materials
Directory of Open Access Journals (Sweden)
Augusto Cannone Falchetto
Full Text Available The use of recycled materials in pavement construction has seen, over the years, a significant increase closely associated with substantial economic and environmental benefits. During the past decades, many transportation agencies have evaluated the effect of adding Reclaimed Asphalt Pavement (RAP, and, more recently, Recycled Asphalt Shingles (RAS on the performance of asphalt pavement, while limits were proposed on the amount of recycled materials which can be used. In this paper, the effect of adding RAP and RAS on the microstructural and low temperature properties of asphalt mixtures is investigated using digital image processing (DIP and modeling of rheological data obtained with the Bending Beam Rheometer (BBR. Detailed information on the internal microstructure of asphalt mixtures is acquired based on digital images of small beam specimens and numerical estimations of spatial correlation functions. It is found that RAP increases the autocorrelation length (ACL of the spatial distribution of aggregates, asphalt mastic and air voids phases, while an opposite trend is observed when RAS is included. Analogical and semi empirical models are used to back-calculate binder creep stiffness from mixture experimental data. Differences between back-calculated results and experimental data suggest limited or partial blending between new and aged binder.
Asphalt modification with used lubricating oil
Energy Technology Data Exchange (ETDEWEB)
Villanueva, A.; Ho, S.; Zanzotto, L. [Calgary Univ., AB (Canada). Schulich School of Engineering, Bituminous Materials Research Laboratory
A method of recycling waste lubricating oil from vehicles was presented. Various asphalt materials were modified with different amounts of lubricating oil and analyzed using standard Superpave tests. Dynamic shear rheometer (DSR) tests were then conducted to in order to obtain high temperature samples. Bending beam rheometer (BBR) and direct tension tests (DTT) were used to obtain low temperature sample profiles. Potential applications for the materials were reviewed. Environmental impacts and costs associated with using the materials were also presented. The study demonstrated that waste lubricating oil can be used as a softening agent in modified asphalt binders using a low temperature grade technique. It was concluded that the low cost of waste lubricating oil in Alberta makes it a potential resource for asphalt modification. The oil modified samples lowered the high-temperature grade and did not improve the overall quality of the asphalt. Further testing is needed to examine the quality and consistency of lubricating oils. 19 refs., 7 tabs., 12 figs.
Microbial Life in a Liquid Asphalt Desert
Schulze-Makuch, Dirk; Haque, Shirin; de Sousa Antonio, Marina Resendes; Ali, Denzil; Hosein, Riad; Song, Young C.; Yang, Jinshu; Zaikova, Elena; Beckles, Denise M.; Guinan, Edward; Lehto, Harry J.; Hallam, Steven J.
Pitch Lake in Trinidad and Tobago is a natural asphalt reservoir nourished by pitch seepage, a form of petroleum that consists of mostly asphaltines, from the surrounding oil-rich region. During upward seepage, pitch mixes with mud and gases under high pressure, and the lighter portion evaporates or is volatilized, which produces a liquid asphalt residue characterized by low water activity, recalcitrant carbon substrates, and noxious chemical compounds. An active microbial community of archaea and bacteria, many of them novel strains (particularly from the new Tar ARC groups), totaling a biomass of up to 107 cells per gram, was found to inhabit the liquid hydrocarbon matrix of Pitch Lake. Geochemical and molecular taxonomic approaches revealed diverse, novel, and deeply branching microbial lineages with the potential to mediate anaerobic hydrocarbon degradation processes in different parts of the asphalt column. In addition, we found markers for archaeal methane metabolism and specific gene sequences affiliated with facultative and obligate anaerobic sulfur- and nitrite-oxidizing bacteria. The microbial diversity at Pitch Lake was found to be unique when compared to microbial communities analyzed at other hydrocarbon-rich environments, which included Rancho Le Brea, a natural asphalt environment in California, USA, and an oil well and a mud volcano in Trinidad and Tobago, among other sites. These results open a window into the microbial ecology and biogeochemistry of recalcitrant hydrocarbon matrices and establish the site as a terrestrial analogue for modeling the biotic potential of hydrocarbon lakes such as those found on Saturn's largest moon Titan.
Sulfur extended asphalt pavement evaluation: Executive summary
Mahoney, J. P.
This summary report overviews two previously issued study reports. One report assesses The availability and pricing of sulfur with respect to sulfur extended asphalt (SEA) paving mixture is assessed. A laboratory oriented testing program which was principally used to examine the durability and aging characteristics of SEA paving mixtures is reported.
Determining and Modeling Asphalt Concrete Response (ACRe)
Erkens, S.M.J.G.; Poot, M.R.
In road engineering research and design the principles of material mechanics have not yet become a standard tool. In this contribution a project aimed at applying these principles to asphalt concrete is presented. Attention is paid to the differences between the standard test procedures and those ba
Investigation of a Hardened Cement Paste Grout
DEFF Research Database (Denmark)
Esteves, Luis Pedro; Sørensen, Eigil Verner
This report documents a series of tests performed on a hardened cement paste grout delivered by the client, Det Norske Veritas A/S.......This report documents a series of tests performed on a hardened cement paste grout delivered by the client, Det Norske Veritas A/S....
Deformation Wave Hardening of Metallic Materials
Directory of Open Access Journals (Sweden)
A.V. Kirichek
Full Text Available The article deals with the machine parts hardening by means of deformation waves generated by the impact system with a waveguide as an intermediary member. The conditions for the efficient use of impact energy for elastoplastic deformation of the processed material and creation of the deep hardened surface layer.
Improved hardening theory for cyclic plasticity.
Vos, R. G.; Armstrong, W. H.
A temperature-dependent version of a combined hardening theory, including isotropic and kinematic hardening, is presented within the framework of recent plasticity formulations. This theory has been found to be especially useful in finite-element analysis of aerospace vehicle engines under conditions of large plastic strain and low-cycle fatigue.
Method of hardening a fluid mass
Zitha, P.L.J.; Jansen, J.D.
The invention relates to a method of hardening a fluid mass in contact with a wall, in a desirable shape. According to the invention, the fluid mass is a magneto-rheological fluid mixture that in addition to at least one hardening component comprises a particulate magnetic component, with minimally
Thermal Properties of Asphalt Mixtures Modified with Conductive Fillers
Directory of Open Access Journals (Sweden)
Byong Chol Bai
Full Text Available This paper investigates the thermal properties of asphalt mixtures modified with conductive fillers used for snow melting and solar harvesting pavements. Two different mixing processes were adopted to mold asphalt mixtures, dry- and wet-mixing, and two conductive fillers were used in this study, graphite and carbon black. The thermal conductivity was compared to investigate the effects of asphalt mixture preparing methods, the quantity, and the distribution of conductive filler on thermal properties. The combination of conductive filler with carbon fiber in asphalt mixture was evaluated. Also, rheological properties of modified asphalt binders with conductive fillers were measured using dynamic shear rheometer and bending beam rheometer at grade-specific temperatures. Based on rheological testing, the conductive fillers improve rutting resistance and decrease thermal cracking resistance. Thermal testing indicated that graphite and carbon black improve the thermal properties of asphalt mixes and the combined conductive fillers are more effective than the single filler.
Percolation Model of Graphite-modified Asphalt Concrete
Institute of Scientific and Technical Information of China (English)
MO Liantong; WU Shaopeng; LIU Xiaoming; CHEN Zheng
The addition of graphite powder in conventional asphalt mixture can produced asphalt concrete with excellent electrical performance. Percolation theory was employed to discuss the relation between the conductivity and graphite content of graphite-modified asphalt concrete. It was found that the results of percolation model are consistent with experimental values. The percolation threshold of graphite-modified asphalt concrete is 10.94% graphite content account for the total volume of the binder phase consisting of asphalt and graphite. The critical exponent is 3.16, beyond the range of 1.6-2.1 for the standard lattice continuous percolation problem. Its reason is that the tunnel conduction mechanism originates near the critical percent content, which causes this system to be not universal. Tunnel mechanism is demonstrated by the nonlinear voltage-current characteristic near percolation threshold.The percolation model is able to well predict the formation and development of conductive network in graphite-modified asphalt concrete.
Viscoelastic Analysis of Asphalt Mixture Based on Creep Test
Directory of Open Access Journals (Sweden)
Lihua Zhao
Full Text Available Two kinds of mineral fibers were added to AC-16C asphalt mixture. Trabecular bending creep experiments of asphalt mixtures were carried out at -10 and 20°C. The influence of mineral fibers on the low temperature viscoelasticity of asphalt mixtures were analyzed systemically. Furthermore, by using Origin, Burgers viscoelastic model was used to investigate the parameter regression for the creep test results at the different temperatures. The results show that the addition of mineral fibers can effectively improve the bending creep rate of asphalt mixtures, indicates the increase of crack resistance of asphalt mixtures. Good agreement between experimental data and Burgers model was found. The parameters of Burgers model at different temperatures can also provide data support for the viscoelastic design of asphalt pavements.
An Improvement in Electrical Properties of Asphalt Concrete
Institute of Scientific and Technical Information of China (English)
WU Shao-peng; MO Lian-tong; SHUI Zhong-he; XUAN Dong-xing; XUE Yong-jie; YANG Wen-feng
Materials such as Koch AH - 70, basalt aggregate, limestone powder and graphite particles were used to prepare conductive asphalt concrete, which is a new type of multi functional concrete. The mix proportion by weight was shown as follows. Fineaggregates (2.36-4.75 mm):fine aggregates (< 2.36mm): limestone powder: asphalt = 120:240: 14:30. The content of added graphite particles ranged from 0% to 20% ( by the Special weight of asphalt concerte). A conductive asphalt concrete with a resistivity around 10-103·Ωm was obtained.attention was paid to the effects of graphite content, graphite physical-chemical properties, asphalt content and temperature on the resistivity. Furthermore, an attempt was made to develop an electrically conductive model for asphalt concrete.
Performance of Recycled Porous Hot Mix Asphalt with Gilsonite Additive
Directory of Open Access Journals (Sweden)
Ludfi Djakfar
Full Text Available The objective of the study is to evaluate the performance of porous asphalt using waste recycled concrete material and explore the effect of adding Gilsonite to the mixture. As many as 90 Marshall specimens were prepared with varied asphalt content, percentage of Gilsonite as an additive, and proportioned recycled and virgin coarse aggregate. The test includes permeability capability and Marshall characteristics. The results showed that recycled concrete materials seem to have a potential use as aggregate in the hot mix asphalt, particularly on porous hot mix asphalt. Adding Gilsonite at ranges 8–10% improves the Marshall characteristic of the mix, particularly its stability, without decreasing significantly the permeability capability of the mix. The use of recycled materials tends to increase the asphalt content of the mix at about 1 to 2% higher. With stability reaching 750 kg, the hot mix recycled porous asphalt may be suitable for use in the local roads with medium vehicle load.
Research on Surfactant Warm Mix Asphalt Construction Technology
Li, Guoliang; Sun, Jingxin; Guo, Xiufeng
Discharging temperature of hot asphalt mixture is about 150°C-185°C, volatilization of asphalt fume harms people's health and fuel cost is high. Jinan Urban Construction Group applies PTL/01 asphalt warm mix agent to produce warm mix asphalt to construction of urban roads' asphalt bituminous pavement. After comparing it with performance of traditional hot asphalt mixture, mixing temperature may be reduced by 30°C-60°C, emission of poisonous gas is reduced, energy conservation and environmental protection are satisfied, construction quality reaches requirements of construction specifications and economic, social and environmental benefits are significant. Thus, it can be used for reference for green construction of urban roads.
Challenges in hardening technologies using shallow-trench isolation
Energy Technology Data Exchange (ETDEWEB)
Shaneyfelt, M.R.; Dodd, P.E.; Draper, B.L.; Flores, R.S.
Challenges related to radiation hardening CMOS technologies with shallow-trench isolation are explored. Results show that trench hardening can be more difficult than simply replacing the trench isolation oxide with a hardened field oxide.
Simultaneous surface engineering and bulk hardening of precipitation hardening stainless steel
DEFF Research Database (Denmark)
Frandsen, Rasmus Berg; Christiansen, Thomas; Somers, Marcel A. J.
This article addresses simultaneous bulk precipitation hardening and low temperature surface engineering of two commercial precipitation hardening stainless steels: Sandvik Nanoflex® and Uddeholm Corrax®. Surface engineering comprised gaseous nitriding or gaseous carburising. Microstructural char....... The duration and temperature of the nitriding/carburising surface hardening treatment can be chosen in agreement with the thermal treatment for obtaining optimal bulk hardness in the precipitation hardening stainless steel.......This article addresses simultaneous bulk precipitation hardening and low temperature surface engineering of two commercial precipitation hardening stainless steels: Sandvik Nanoflex® and Uddeholm Corrax®. Surface engineering comprised gaseous nitriding or gaseous carburising. Microstructural...... characterisation of the cases developed included X-ray diffraction analysis, reflected light microscopy and micro-hardness testing. It was found that the incorporation of nitrogen or carbon resulted in a hardened case consisting of a combination of (tetragonal) martensite and expanded (cubic) austenite...
Determination of Rheological Properties of Bio Mastic Asphalt
R. Muniandy; H. Jafariahangari; Yunus, R.; S. Hassim
Due to the high oil prices the price of asphalt binder has increased tremendously. This scenario has warranted demand for higher viscosity cheaper asphalt for pavement construction. A study was conducted to take advantage of the Empty Fruit Bunch (EFB) of Date and Oil Palm trees (which are considered as waste) to produce cellulose fiber to be used as additives in the asphalt binder. If these EFB's could be beneficially utilized in any application, it would reduce the load on the nation's land...
Evaluation of asphalt-rubber membrane field performance
Shuler, S.; Gallaway, B. M.; Epps, J. A.
This report presents a record of asphalt-rubber membrane field performance in Texas. An evaluation of performance is presented for forty-five separate projects in thirteen state highway districts. Approximately 850 lane miles of highways are represented by materials constructed as stress absorbing membranes (asphalt-rubber seal coats beneath asphalt concrete overlay). All projects reviewed were constructed between June, 1976 and September, 1981.
Comparison between asphalt rubber and conventional mixtures in overlay design
Fontes, Liseane P. T. L.; Trichês, Glicério; Pereira, Paulo A. A.; Pais, Jorge C.
Asphalt modified with crumb rubber has been used to produce asphalt rubber mixtures for pavement overlays subjected to heavy loads and high temperatures. Under severe conditions, these mixtures are capable of resisting permanent deformations, having an extended fatigue life and resisting crack propagation in comparison to conventional ones. A laboratory research was conducted to determine the performance properties of overlays with asphalt rubber mixtures produced through wet processes using ...
Performance Evaluation of Semiplastic Recycled Cold Asphalt Using Noncement Binders
Lee, Byung Jae; Bang, Jin Wook; Kim, Jeong Su; Jang, Young Il
The optimal mixing conditions for semiplastic recycled cold asphalt, which recycled waste asphalt and used noncement binders (NCB), were assessed through verification of the performance. The NCB of 6% desulfurization gypsum mixing was found to have the most outstanding properties. For the Marshall stability, 4% (NCB) filler mixing brought about a 1.92-time strength increase effect compared to OPC (2%) and was improved when using modified asphalt and SBR. The flow test results showed that alth...
Extending the Life of Asphalt Longitudinal Paving Joints
Hedges, Rex; Brownridge, Jim
Is premature asphalt joint failure bringing your PASER number down? Participants will learn how applying asphalt preservative seals directly to the asphalt longitudinal paving joint can restore plasticity and flexibility and how application of in-depth sealing methods will protect against harmful UV rays, prevent oxidation, and waterproof against chloride intrusion. Rehabilitation methods to repair poorly performing and failed paving joints will also be covered.
Porous Flame-retarded Asphalt Pavement for Highway Tunnel
Institute of Scientific and Technical Information of China (English)
HU Shuguang; HUANG Shaolong; Ding Qingjun
A new way to improve the tunnel fire protection by using flame-retarded porous asphalt pavement containing ATH powders was introduced. Based on the miniature burning test designed and conducted, the burning time and temperature of porous asphalt (PA) and flame-retarded porous asphalt (FRPA) were studied comparing with cement concrete pavement, dense-graded HMA and S MA. Results of burning test and pavement performance test indicate that FRPA is appropriate and suitable as the pavement material of highway tunnel.
Use of scrap rubber in asphalt pavement surfaces
Eaton, Robert A.; Roberts, Richard J.; Blackburn, Robert R.
Scrap tire rubber was mixed into an asphalt concrete wearing course to study the effect of ice disbonding from the pavement surface under traffic. Rubber contents of 0, 3, 6, and 12 percent by weight were studied. Initial laboratory ice disbonding test results led to the development of a new paving material, Chunk Rubber Asphalt Concrete (CRAC), that uses larger pieces of rubber in a much denser asphalt concrete mix. Strength values doubled and ice disbonding performance was enhanced.
Evaluation of Hydrated Lime Filler in Asphalt Mixtures
Mohammed Abbas Hasan Al-Jumaily
Mineral filler is one of important materials and affecting on properties and quality of asphalt mixtures .There are different types of mineral filler depended on cost and quality , the matter encourages us to achieve this study to evaluate hydrated lime filler effects on properties of asphalt mixes related with strength and durability. Conventional asphaltic concrete mixtures with Portland cement and soft sandstone fillers and mixtures modified with hydrated lime were evaluated for their fund...
Increasing the rate of recycled asphalt: an experimental study
Directory of Open Access Journals (Sweden)
Marjan TUŠAR
Full Text Available Asphalt is material that can be recycled. In particular reclaimed asphalt (RA contains aged binder, which limits the reuse of RA. In this study the rate of recycled asphalt was increased by adding a rejuvenator containing paraffin. The authors investigated the effect of the rejuvenator in laboratory and in plant prepared samples of asphalt mixture. In laboratory samples with different percentage of RA (0%, 10%, 30%, 50% and rejuvenator were prepared. In asphalt plant only asphalt mixture with highest amount of RA and rejuvenator and control mixture without RA were prepared. On samples were conducted different tests, e.g. determining softening point, Fraass breaking point, penetration, indirect tensile strength. Results on extracted bitumen showed increase in softening point and decrease in Fraass breaking point with increasing percentage of RA and rejuvenator, meaning that service temperature of binders increased. Asphalt samples prepared in asphalt plant were laid on test field. Asphalt with RA and rejuvenator was built in at lower temperature (round 100 °C. Mixtures with RA and rejuvenator have better low temperature properties confirmed with Thermal Stress Restrained Specimen Test (TSRST method, but are less resistant to compaction and less sensitive to water than control mixture. For comparison of long term behaviour wheel tracking test was performed on mixtures built in test field. A week after paving, the control mixture showed better properties, but one year later the results were opposite, asphalt containing RA and rejuvenator was more resistant to rutting. From the results of this experimental study the following was concluded: the amount of RA can be increased by using rejuvenator and the quality of such asphalt mixture is in most cases equal or even better than asphalt mixture made of virgin materials. By using RA we preserve nature, reduce usage of virgin raw materials, but it is cost effective only if recycling degree is high
Bone Glue Modified Asphalt: A Step towards Energy Conservation and Environment Friendly Modified Asphalts
Rizvi, Hashim Raza; Gallo, August A.
Asphalt has been modified for the past several decades using various additives, including synthetic polymers. Polymer modification improves structural and engineering characteristics of the binder, which is a result of improvement in rheological characteristics of binder as well as its adhesion capability with the aggregate. Such enhancement inevitably enhances the performance characteristics of hot mix asphalts (HMA) such as fatigue life, resistance to rutting, and thermal cracking. Even though polymer-modified HMA is popular in North America and European countries, its use is still limited in developing countries of Southeast Asia due to high costs associated with its manufacturing, processing, and energy consumption. In this study, a new kind of asphalt modifier derived from animal wastes, such as bones, hides, and flesh commonly known as Bone Glue, is studied. This biomaterial which is a by-product of food and cattle industries is cheap, conveniently available, and produced locally in developing countries. The results of the research study showed that the bone glue can easily be mixed with asphalt without significantly altering the asphalt binder's viscosity and mixing and compaction temperatures of HMA. Additionally, improvements in complex shear modulus for a range of temperatures were also determined and it was found that complex shear modulus was improved by bone glue modification.
Performance Evaluation of Semiplastic Recycled Cold Asphalt Using Noncement Binders
Directory of Open Access Journals (Sweden)
Byung Jae Lee
Full Text Available The optimal mixing conditions for semiplastic recycled cold asphalt, which recycled waste asphalt and used noncement binders (NCB, were assessed through verification of the performance. The NCB of 6% desulfurization gypsum mixing was found to have the most outstanding properties. For the Marshall stability, 4% (NCB filler mixing brought about a 1.92-time strength increase effect compared to OPC (2% and was improved when using modified asphalt and SBR. The flow test results showed that although an increase dosage of filler and SBR decreased the flow value of the semiplastic recycled cold asphalt, an increase dosage of asphalt emulsion improved the flow value. The indirect tensile strength and liquid immersion residual stability for the condition with greatest Marshall stability were most outstanding with 0.95 MPa and 83.6%, respectively. Evaluation of the recycled cold asphalt abrasion durability revealed that for the case of mixing more than 4% NCB the mass loss rate was lower than 20%. The abrasion durability was found to improve when using modified emulsified asphalt and SBR substitution. From the test results, it was found that the optimal mixing proportion of semiplastic recycled cold asphalt satisfied mechanical properties and durability is NCB with 4%, emulsified asphalt with 3%, and SBR substitution with 20%.
Creep Characteristics of Crumb Rubber Modified Asphalt Binder
Institute of Scientific and Technical Information of China (English)
WANG Lan; CHANG Chunqing; XING Yongming
Crumb rubber modified asphalt containing 20 percent crumb rubber particles of 30mesh has been examined by Scanning Electron Microscope (SEM) to observe the microcosmic appearance and the characteristic distribution of crumb rubber particles in asphalt. The SEM pictures reveal that the crumb rubber particles distribute evenly in the asphalt and they are compatible well with asphalt. The shear creep test of crumb rubber modified asphalt was carried out at - 10 ℃ and 40 ℃ by Dynamic Shear Rheology (DSR). The shearing deformation at different temperature and creep stiffness modulus curve at loading stage of crumb rubber modified asphalt have been measured. The stiffness modulus of crumb rubber modified asphalt is much temperature sensitive and it decays much quick at the early stage of loading than normal asphalt. The rate of decay of stiffness modulus is slow at the subsequent stage and stiffness modulus approaches to a stable value at the final stage at a higher temperature. In addition, Burgers model is suitable to describe and simulate experimental results of viscoelastic properties of the crumb rubber modified asphalt.
Safety evaluation of asphalt products for final disposal
International Nuclear Information System (INIS)
Under the present situation, the wastes concentrated according to the radioactivity level, the properties and the environmental conditions are usually solidified in view of limiting the escape of the radioactive substances to the environment as small as possible by containment. The materials used for the solidification are cement, asphalt, plastics, ceramics and so on, and the selection is made by taking the kinds and radioactivity level of wastes, final disposing method, economy and handling into consideration. Asphalt is more suitable than cement to the wastes coming from PWR power plants, which contain boric acid for controlling nuclear reaction, and the effect of reducing the volume of wastes is high. It is economical when a certain scale is reached, accordingly recently, the use of asphalt for the solidification of wastes is going to increase. For the solidification of low level wastes, straight-run asphalt is suitable, and for high level wastes, heat-resistant blown asphalt is suitable. Asphalt-solidified bodies can contain 40-60 wt.% of wastes without any problem. The present situation of asphalt solidification in foreign countries, the physical properties required for the disposal of asphalt-solidified bodies, and the leaching, combustibility, radiation resistance and form stability of asphalt-solidified bodies are described. (Kako, I.)
Field testing of asphalt-emulsion radon-barrier system
International Nuclear Information System (INIS)
Three years of laboratory and field testing have demonstrated that asphalt emulsion seals are effective radon diffusion barriers. Both laboratory and field tests in 1979, 1980 and 1981 have shown that an asphalt emulsion seal can reduce radon fluxes by greater than 99.9%. The effective diffusion coefficient for the various asphalt emulsion admix seals averages about 10-6 cm2/s. The 1981 joint field test is a culmination of all the technology developed to date for asphalt emulsion radon barrier systems. Preliminary results of this field test and the results of the 1980 field test are presented. 18 figures, 6 tables
Hanford Permanent Isolation Barrier Program: Asphalt technology development
Energy Technology Data Exchange (ETDEWEB)
Freeman, H.D.; Romine, R.A.
An important component of the Hanford Permanent Isolation Barrier is the use of a two-layer composite asphalt system, which provides backup water diversion capabilities if the primary capillary barrier fails to meet infiltration goals. Because of asphalt`s potential to perform to specification over the 1000-year design life criterion, a composite asphalt barrier (HMAC/fluid-applied polymer-modified asphalt) is being considered as an alternative to the bentonite clay/high density poly(ethylene) barriers for the low-permeability component of the Hanford Permanent Isolation Barrier. The feasibility of using asphalt as a long-term barrier is currently being studied. Information that must be known is the ability of asphalt to retain desirable physical properties over a period of 1000 years. This paper presents the approach for performing accelerated aging tests and evaluating the performance of samples under accelerated conditions. The results of these tests will be compared with asphalt artifact analogs and the results of modeling the degradation of the selected asphalt composite to make life-cycle predictions.
Modification of Asphalt by the Use of Crumb Rubber
Directory of Open Access Journals (Sweden)
Shah Room
Full Text Available Health aspects enforced to ponder a study on asphalt which incorporate rubber crumbs to increase strength and flexibility of asphalt. Disposal of waste tires is a menace and it's a serious problem globally because it is not easily biodegradable as these tires consume large spaces, open burning cause serious problems. By the use of rubber tires, this scrap is utilized efficiently and reduces the cost of asphalt to produce economical system. The asphalt is absorbed by the rubber particles which swells at high temperature allowing greater concentration of liquid asphalt. The partial replacement of crumb rubber in asphalt is 5%, 10%, 15%, and 20% (D05, D10, D15, and D20. The analysis of incorporated asphalt was done in hot mix asphalt. The generated results showed that the value for resilient modulus and creep stiffness is more as compared to the conventional asphalt and in the accumulated strain the values are much lesser which is positive approach.
Effects of reclaimed asphalt pavement on indirect tensile strength test of foamed asphalt mix tested in dry condition
International Nuclear Information System (INIS)
Indirect tensile strength (ITS) test was conducted to analyse strength of the foamed asphalt mixes incorporating reclaimed asphalt pavement. Samples were tested for ITS after cured in the oven at 40°C for 72 hours. This testing condition known as dry condition or unconditioned. Laboratory results show that reclaimed asphalt pavement (RAP) contents insignificantly affect the ITS results. ITS results significantly affected by foamed bitumen contents.
Effects of reclaimed asphalt pavement on indirect tensile strength test of foamed asphalt mix tested in dry condition
Yati Katman, Herda; Rasdan Ibrahim, Mohd; Yazip Matori, Mohd; Norhisham, Shuhairy; Ismail, Norlela
Indirect tensile strength (ITS) test was conducted to analyse strength of the foamed asphalt mixes incorporating reclaimed asphalt pavement. Samples were tested for ITS after cured in the oven at 40°C for 72 hours. This testing condition known as dry condition or unconditioned. Laboratory results show that reclaimed asphalt pavement (RAP) contents insignificantly affect the ITS results. ITS results significantly affected by foamed bitumen contents.
Extending the Lifespan of Porous Asphalt Concrete
Zhang, Y.
Porous Asphalt (PA) concrete is widely used as a surfacing layer on highways in the Netherlands. The service life of PA wearing courses is limited because of the fact that it is vulnerable to raveling. The possibilities of applying preventive maintenance to PA wearing courses by means of spraying rejuvenation products on the pavement surfaces are being investigated with high interest in the Netherlands. A material which has the ability to penetrate into the bituminous binder and soften (rejuv...
Classification of recycled asphalt (RA) material
Wendling, Louisette; DE LA ROCHE SAINT ANDRE, Chantal; Gaudefroy, Vincent; MARSAC, Paul; TEBALDI, Gabriele; DAVE, Eshan; HUGENER, Martin; BOCCI, Maurizio; Loizos, Andreas; JENKINS, Kim; MARRADI, Alessandro; Grilli, Andrea; GRAZIANI, Andrea; Pasetto, Marco; MURAYA, Patrick
Use of recycled asphalt pavements (RA) in pavement rehabilitation processes is continuously growing as recycling techniques, such as cold recycling (CR), are being utilized in increasing magnitude. The focus of this paper is on developing a state of the art and state of the practice summary of processes used for classification of RA. A variety of topics were explored through an exhaustive literature search, these include RAP production methods, definition of RA materials, stockpiling practice...
The influence of Glassex additive on properties of microwave-hardened and self- hardened moulding sands with water glass
Directory of Open Access Journals (Sweden)
K. Major-Gabryś
Full Text Available The article takes into consideration the researches concerning inserting the Glassex additive to the microwaved-hardened and self- hardened moulding sands with water glass. In the research different types of ester hardeners to self-hardened moulding sands with water glass were used. The influence of Glassex additive on retained strength of moulding sands with different hardeners and prepared by different technologies of hardening were tested. The influence of different hardeners and the technology of hardening on retained strength of moulding sand with water glass and the Glassex additive were also estimated.
Active carbon production from modified asphalt
International Nuclear Information System (INIS)
A granular activated carbons (GACs) have been prepared from some local raw materials such as Qiayarah asphalt (QA) after some modification treatments of this asphalt by various ratios of its original constituents (asphaltenes and maltens) at 180 degree C. Thermal carbonization method by sulfur and steam physical activation have been used for AC preparation. The carbons thus prepared were characterized in the term of iodine, methylene blue (MB), P-nitro phenol (PNP) and CCl4 adsorption. The BET surface area of the prepared ACs has been estimated via a calibration curve between iodine numbers and surface area determined from N2 adsorption isotherm from previous studies, also, the surface area of the prepared ACs were determined through another methods such as retention method by ethylene glycol mono ethyl ether (EGME), adsorption from vapor phase using acetone vapor and adsorption from solution method using PNP and MB as solutes. The results referred to the success of modification method for preparing ACs of good micro porosity as compared with the AC from the untreated asphalt as well as the commercial sample. (author)
Method of interrupting asphalt solidifying operation
International Nuclear Information System (INIS)
Purpose: To shorten the time required for interrupting operation, by specifying methods of supplying and interrupting liquid wastes, water and asphalts. Method: Electrical power supply for a heat medium heater is disconnected simultaneously with the start for the stopping operation. The temperature for the heat medium is detected by a heat medium thermometer, the flow rate of a waste liquid supply pump is reduced by way of a rotation controller for the liquid waste supply pump and the amount of liquid wastes supplied is gradually decreased along with the reduction in the temperature for the heat medium. Then, when the temperature for the heat medium lowered to about 190 - 2100C, supply of the liquid wastes is interrupted and cleaning water is supplied to a liquid wastes supply tank while closing the liquid wastes supply tank main valve and opening a cleaning water valve to thereby clean the radioactive substances. Then, after stopping the supply of the cleaning water, asphalt is continued to be supplied for several minutes, the radioactive substances deposited in an evaporator and an agitation blade are sufficiently washed out. Then, after stopping the asphalt tank, operations for the driving device and the heat medium pump are stopped. This enables cooling for the heat medium in a short time using no exclusive heat medium cooler, as well as clean the radioactive substances. (Horiuchi, T.)
Hot asphalt burns: a review of injuries and management options.
Bosse, George M; Wadia, Shernaz A; Padmanabhan, Pradeep
Hot asphalt burns to human tissue can increase the likelihood of infection and potential conversion of partial thickness to full-thickness injuries. Successful intervention for hot asphalt burns requires immediate and effective cooling of the asphalt on the tissue followed by subsequent gradual removal of the cooled asphalt. A review of the literature reveals that multiple substances have been used to remove asphalt, including topical antibiotics, petroleum jelly, a commercial product known as De-Solv-It (ORANGE-SOL, Chandler, AZ), sunflower oil, baby oil, liquid paraffin, butter, mayonnaise, and moist-exposed burn ointment (MEBO). Although many of these products may be effective in the removal of asphalt, they may not be readily available in an emergency department setting. Topical antibiotics are readily available, are more commonly described in the medical literature, and would be expected to be effective in the removal of asphalt. We developed guidelines for on scene (first-aid) management and the initial care of such patients upon presentation to a health care facility. These guidelines emphasize the principles of early cooling, gradual removal of adherent asphalt using topical antibiotics, and avoidance of the use of topical agents, which are likely to result in tissue toxicity. PMID:24630605
Hanford Permanent Isolation Barrier Program: Asphalt technology development
International Nuclear Information System (INIS)
An important component of the Hanford Permanent Isolation Barrier is the use of a two-layer composite asphalt system, which provides backup water diversion capabilities if the primary capillary barrier fails to meet infiltration goals. Because of asphalt's potential to perform to specification over the 1000-year design life criterion, a composite asphalt barrier (HMAC/fluid-applied polymer-modified asphalt) is being considered as an alternative to the bentonite clay/high density poly(ethylene) barriers for the low-permeability component of the Hanford Permanent Isolation Barrier. The feasibility of using asphalt as a long-term barrier is currently being studied. Information that must be known is the ability of asphalt to retain desirable physical properties over a period of 1000 years. This paper presents the approach for performing accelerated aging tests and evaluating the performance of samples under accelerated conditions. The results of these tests will be compared with asphalt artifact analogs and the results of modeling the degradation of the selected asphalt composite to make life-cycle predictions
Including asphalt cooling and rolling regimes in laboratory compaction procedures
Bijleveld, F.R.; Doree, A.G.; Kim,
Given the various changes occurring in the asphalt construction industry, improved process and quality control is becoming essential. The significance of appropriate rolling and compaction for the quality of asphalt is widely acknowledged and vital for improved process control. But what constitutes
Durability ofAsphalt in Different Corrosion Solution
Institute of Scientific and Technical Information of China (English)
CHEN Shuanfa; GUAN Bowen; XIONG Rui; SHENG Yanping; HE Rui
The corrosion to asphalt mixture under different kinds of corrosion solution,such as pH=2 solution,pH=12 solution,pH =12 solution and 10% Na2SO4 solution,was studied.The performance attenuation of asphalt mixture was analyzed under the normal environment and the freeze-thaw environment,and the analysis was given on the sensitivity of the test results to the evaluation index.The experimental results show that the performance of asphalt mixture is attenuated faster under the acidic solution,alkaline solution and sulfate solution.Corrosion factor Kc,freeze-thaw corrosion factor Kf,and freeze-thaw effect factor Kfc are proposed to evaluate asphalt mixture resistance to corrosion in different kinds of corrosion solution.The values of Kc and Kfc decrease with the increasing of corrosion time.The change rule of Kf show that the rate of corrosion is decreased by the action of freeze-thaw in acidic solution and in alkaline solution,but is increased by the action of freeze-thaw in sulfate solution.The microscopic analysis indicates that acid solution reacts with aggregate of asphalt mixture,alkaline solution reacts with asphalt cement of asphalt mixture,the surface tension of sulfate solution and crystallization of sulfate are the main reasons which weak the performance of asphalt mixture.
Effects of conductive fillers on temperature distribution of asphalt pavements
International Nuclear Information System (INIS)
The sun provides a cheap and abundant source of clean and renewable energy. Solar cells have been used to capture this energy and generate electricity. A more useful form of the solar cell would be asphalt pavements, which get heated up by solar radiation. Graphite powders are utilized as thermal conductive fillers to make an asphalt collector conductive so as to improve the efficiency of the asphalt collector. Accounting for the important application conditions and evaluating the effects of the heat conductive materials and the solar energy absorbability of the conductive asphalt collector, a finite element model has been developed to predict temperature distributions in the conductive asphalt solar collector. In this study, an experimental validation exercise was conducted using the measured data taken from full-depth asphalt slabs. Validation results showed that the model can satisfactorily predict the temperature distributions in asphalt concrete slabs. The optimal depth is 25-50 mm for placing pipes that serve as the heat exchanger. Meanwhile, the effect of the surroundings on the solar energy potential of the asphalt collector was noticeable.
Effects of conductive fillers on temperature distribution of asphalt pavements
Mingyu, Chen; Shaopeng, Wu; Yuan, Zhang; Hong, Wang
The sun provides a cheap and abundant source of clean and renewable energy. Solar cells have been used to capture this energy and generate electricity. A more useful form of the solar cell would be asphalt pavements, which get heated up by solar radiation. Graphite powders are utilized as thermal conductive fillers to make an asphalt collector conductive so as to improve the efficiency of the asphalt collector. Accounting for the important application conditions and evaluating the effects of the heat conductive materials and the solar energy absorbability of the conductive asphalt collector, a finite element model has been developed to predict temperature distributions in the conductive asphalt solar collector. In this study, an experimental validation exercise was conducted using the measured data taken from full-depth asphalt slabs. Validation results showed that the model can satisfactorily predict the temperature distributions in asphalt concrete slabs. The optimal depth is 25-50 mm for placing pipes that serve as the heat exchanger. Meanwhile, the effect of the surroundings on the solar energy potential of the asphalt collector was noticeable.
Crack repair of asphalt concrete with induction energy
García, A.; Schlangen, E.; Ven, M. van de; Vliet, D. van
It is well known that the healing rates of asphalt courses increase with the temperature. A new method, induction heating, is used in this paper to increase the lifetime of asphalt concrete pavements. Mastic will be first made electrically conductive by the addition of conductive fibers. Then it wil
7 CFR 2902.36 - Concrete and asphalt release fluids.
... 7 Agriculture 15 2010-01-01 2010-01-01 false Concrete and asphalt release fluids. 2902.36 Section... PROCUREMENT Designated Items § 2902.36 Concrete and asphalt release fluids. (a) Definition. Products that are designed to provide a lubricating barrier between the composite surface materials (e.g., concrete...
Laboratory and Field Asphalt Fatigue Performance, Matching Theory with Practice
Pramesti, F.P.
This thesis investigates the relationship between predicted and observed fatigue life of asphalt. This study also investigates the positive effects of modifying bitumen with Retona, a bitumen modifier produced in Indonesia from natural asphalt rock sources, on pavement performance in terms of increa
Characterization of Failure and Permanent Deformation Behaviour of Asphalt Concrete
Wang, J.G.
Asphalt concrete is a viscoelastic material consisting of aggregates, filler and bitumen. The response of asphalt concrete is highly dependent on temperature, loading rate and confining pressure. Permanent deformation is one of the most important distresses developing during the flexible pavement se
Improving the quality of asphalt coating with carbon nanomodifiers
Larisa, Urkhanova; Nikolay, Shestakov; Aleksandr, Semenov; Natalya, Smirnyagina; Irina, Semenova
This article deals with the possibility of modifying the binder by adding carbon nanomodifier to bitumen to improve the quality of asphalt. Addition of 0.05%-0.5% of nanomodifier significantly changes the properties of bitumen. Asphalt with this astringent has increased strength, heat resistance and shear resistance.
40 CFR 443.30 - Applicability; description of the asphalt roofing subcategory.
... asphalt roofing subcategory. 443.30 Section 443.30 Protection of Environment ENVIRONMENTAL PROTECTION... MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.30 Applicability; description of the asphalt roofing subcategory. The provisions of this subpart are applicable to...
40 CFR 443.20 - Applicability; description of the asphalt concrete subcategory.
... asphalt concrete subcategory. 443.20 Section 443.20 Protection of Environment ENVIRONMENTAL PROTECTION... MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Concrete Subcategory § 443.20 Applicability; description of the asphalt concrete subcategory. The provisions of this subpart are applicable to...
40 CFR 443.40 - Applicability; description of the linoleum and printed asphalt felt subcategory.
... linoleum and printed asphalt felt subcategory. 443.40 Section 443.40 Protection of Environment... PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.40 Applicability; description of the linoleum and printed asphalt felt subcategory....
40 CFR 443.10 - Applicability; description of the asphalt emulsion subcategory.
... asphalt emulsion subcategory. 443.10 Section 443.10 Protection of Environment ENVIRONMENTAL PROTECTION... MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.10 Applicability; description of the asphalt emulsion subcategory. The provisions of this subpart are applicable to...
Minimum distortion induction hardening of crankshafts; Verzugsminimiertes Induktionshaerten von Kurbelwellen
Energy Technology Data Exchange (ETDEWEB)
Dappen, Stefan; Amiri, Farsad [SMS Elotherm GmbH, Remscheid (Germany)
On induction hardening of crankshafts, undesirable distortions occur on the workpiece, especially during fillet hardening. The process patented by SMS Elotherm solves this problem by a combination of distortion simulations, a suitable hardening sequence, systematic power control and special mechanical handling. This article presents the fundamentals and the current techniques of minimum distortion hardening. (orig.)
Mechanical Properties of Asphalt Pavement Structure in Highway Tunnel
Institute of Scientific and Technical Information of China (English)
SHI Chun-xiang; GUO Zhong-yin
A linear full 3D finite element method (FEM) was performed in order to present the key design parameters of highway tunnel asphalt pavement under double-wheel load on rectangular loaded area considering horizontal contact stress induced by the acceleration/deceleration of vehicles. The key design parameters are the maximum horizontal tensile stresses at the surface of the asphalt layer, the maximum horizontal tensile stresses at the bottom of the asphalt layer and the maximum vertical shear stresses at the surface of the as- phalt layer were calculated. The influencing factors such as double-wheel weight; asphalt layer thickness; base course stiffness modulus and thickness; and the contact conditions among the structure layers on these key design parameters were also examined separately to propose construction procedures of highway tunnel asphalt pavement.
Monitoring asphalt pavement damages using remote sensing techniques
Mettas, Christodoulos; Themistocleous, Kyriacos; Neocleous, Kyriacos; Christofe, Andreas; Pilakoutas, Kypros; Hadjimitsis, Diofantos
One of the main issues in the maintenance plans of road agencies or governmental organizations is the early detection of damaged asphalt pavements. The development of a smart and non-destructive systematic technique for monitoring damaged asphalt pavements is considered a main priority to fill this gap. During the 1970's, remote sensing was used to map road surface distress, while during the last decade, remote sensing became more advanced, thereby assisting in the evolution of the identification and mapping of roads. Various techniques were used in order to explore condition, age, weaknesses and imperfections of asphalted pavements. These methods were fairly successful in the classification of asphalted surfaces and in the detection of some of their characteristics. This paper explores the state of the art of using remote sensing techniques for monitoring damaged pavements and some typical spectral profiles of various asphalt pavements in Cyprus area acquired using the SVC1024 field spectroradiometer.
Preparation of Flame Retardant Modified with Titanate for Asphalt Binder
Directory of Open Access Journals (Sweden)
Bo Li
Full Text Available Improving the compatibility between flame retardant and asphalt is a difficult task due to the complex nature of the materials. This study explores a low dosage compound flame retardant and seeks to improve the compatibility between flame retardants and asphalt. An orthogonal experiment was designed taking magnesium hydroxide, ammonium polyphosphate, and melamine as factors. The oil absorption and activation index were tested to determine the effect of titanate on the flame retardant additive. The pavement performance test was conducted to evaluate the effect of the flame retardant additive. Oxygen index test was conducted to confirm the effect of flame retardant on flame ability of asphalt binder. The results of this study showed that the new composite flame retardant is more effective in improving the compatibility between flame retardant and asphalt and reducing the limiting oxygen index of asphalt binder tested in this study.
Laboratory Mix Design of Asphalt Mixture Containing Reclaimed Material
Directory of Open Access Journals (Sweden)
Davide Lo Presti
Full Text Available This paper presents a study on the production of asphalt test specimens in the laboratory containing reclaimed asphalt. The mixtures considered were stone mastic asphalt concrete mixtures containing up to 30% of reclaimed asphalt. Specimens were compacted to the reference density obtained from the Marshall mix design. Gyration compaction method was used for preparing specimens for the experimental programme, while coring and cutting methods and X-ray computed tomography (CT were used to investigate the change in properties within the specimens and to validate the selected methodology. The study concluded that gyratory compaction is suitable to produce homogeneous test specimens also for mixtures containing high amount of reclaimed asphalt. Nevertheless, preliminary trials for each material are mandatory, as well as final coring and trimming of the specimens due to side effects.
Effect of ageing on fatigue properties of asphalt
Institute of Scientific and Technical Information of China (English)
王佶; 庞凌; 吴少鹏; 刘全涛; 陈筝
The fatigue properties of asphalts were investigated after various laboratory simulation ageing tests and outdoor natural exposure ultraviolet radiation ageing,by dynamic shear rheometer(DSR) time sweep fatigue test in constant strain model and a new type of specimen which was introduced to avoid the problem of adhesion failure between rotor and asphalt binder.The results show that outdoor natural exposure ageing(NEA) causes the decrease of retained fatigue life distinctly,and photodegradation caused by outdoor NEA of 1 250 μm thin films asphalt for three months,is found to be severer than pressure ageing vessel(PAV) with respects to retained fatigue life.The effect of photodegradation increases as the time of outdoor NEA increases.DSR time sweep fatigue test in constant strain indicates that the aged styrene-butadiene-styrene(SBS) modified asphalt still displays better fatigue properties than the corresponding base asphalt after ageing.
Utilization of recycled asphalt concrete with warm mix asphalt and cost-benefit analysis.
Oner, Julide; Sengoz, Burak
The asphalt paving industries are faced with two major problems. These two important challenges are generated with an increase in demand for environmentally friendly paving mixtures and the problem of rapidly rising raw materials. Recycling of reclaimed asphalt pavement (RAP) is a critical necessity to save precious aggregates and reduce the use of costly bitumen. Warm Mix Asphalt (WMA) technology provides not only the option of recycling asphalt pavement at a lower temperature than the temperature maintained in hot mixtures but also encourages the utilization of RAP and therefore saves energy and money. This paper describes the feasibility of utilizing three different WMA additives (organic, chemical and water containing) at recommended contents with different percentages of RAP. The mechanical properties and cost-benefit analysis of WMA containing RAP have been performed and compared with WMA without RAP. The results indicated that, 30%, 10% and 20% can be accepted as an optimum RAP addition related to organic, chemical and water containing additives respectively and organic additive with 30% RAP content has an appreciable increase in tensile strength over the control mix. It was also concluded that the RAP with WMA technology is the ability to reduce final cost compared to HMA and WMA mixtures. PMID:25574851
Directory of Open Access Journals (Sweden)
Yuri KALGIN
Full Text Available The problem of prediction of the service life of asphalt concrete surface constructed with modified asphalt concrete application onto a traffic lane is examined. Asphalt concrete behaviour in road surface under the traffic loads was analysed. There were shown The results of experiments and their mathematical analysis of the assessment of standard and modified cold asphalt concrete fatigue life on road surface were shown. The service life of an asphalt concrete surface covered with standard and modified cold asphalt concrete is examined. The prediction has been received with an account of stress relaxation processes in asphalt concrete pavement and unevenness of traffic load application.
Infrared Camera Analysis of Laser Hardening
Directory of Open Access Journals (Sweden)
J. Tesar
Full Text Available The improvement of surface properties such as laser hardening becomes very important in present manufacturing. Resulting laser hardening depth and surface hardness can be affected by changes in optical properties of material surface, that is, by absorptivity that gives the ratio between absorbed energy and incident laser energy. The surface changes on tested sample of steel block were made by engraving laser with different scanning velocity and repetition frequency. During the laser hardening the process was observed by infrared (IR camera system that measures infrared radiation from the heated sample and depicts it in a form of temperature field. The images from the IR camera of the sample are shown, and maximal temperatures of all engraved areas are evaluated and compared. The surface hardness was measured, and the hardening depth was estimated from the measured hardness profile in the sample cross-section. The correlation between reached temperature, surface hardness, and hardening depth is shown. The highest and the lowest temperatures correspond to the lowest/highest hardness and the highest/lowest hardening depth.
Surface Modification of Fire-retardant Asphalt with Silane Coupling Agent
Institute of Scientific and Technical Information of China (English)
CHEN Huiqiang; TANG Boming
The theory and approach of the surface modified of asphalt fire-retardant with silane coupling agent were introduced,The optimum silane dosage was determined,and the structure and properties of the asphalt fire-retardant before and after the surface modification were characterized by infrared spectrum and thermo gravimetric analysis.The dispersion effect of asphalt fire-retardant was studied.The influence of the surface modification on the hydrophilicity and lipophilicity of the asphalt fire-retardant was analyzed.The experimental results showed that there were physical and chemical interactions between the silane coupling agent and the asphalt fire-retardant,which reduced the surface polarity of the asphalt fire retardant.The optimum silane coupling agent dosage was 0.95% of the asphalt fire retardant.The surface modification improved the thermal stability,dispersibility and lipophilicity of the asphalt fire retardant,which enhanced the compatibility between asphalt fire retardant and asphalt.
Evaluation of Warm Mix Asphalt Technologies and Recycled Asphalt Pavements in Truckee Meadows, Nevada
Diaz Montecino, Cristian
This study evaluated the properties and laboratory-performance of Hot Mix Asphalt (HMA) and Warm Mix Asphalt (WMA) mixtures with different levels of Recycled Asphalt Pavements (RAP) content: none for control mixtures, around 15% by dry weight of aggregates, and more than 30% by dry weight of aggregates. The rheological properties were evaluated for virgin and recovered RAP asphalt binders. The target amount of RAP in the mixtures was determined by using Blending Charts and Mortar Experiments. The mixtures are design through the guidelines established in Marshall Mix Design Method considering additional modifications for RAP and WMA from Superpave Mix Design. The mixtures are evaluated for their resistance to moisture damage by means of measuring the Dynamic Modulus |E*| after three freeze/thaw cycles and the indirect tensile strength after one and three freeze/thaw cycles. The resistance of the mixtures to permanent deformation was also evaluated by using the Asphalt Mixture Performance Tester (AMPT) to measure the flow number (FN). For this study, it was determined that the resistance to moisture damage decreases as the number of freeze/thaw cycles increases for most of the evaluated mixtures. Mixtures exhibited an increase in dynamic modulus as the RAP percentage increased. A decrease in the resistance to moisture damage was detected with the increase in RAP content for most of the mixtures. HMA mixtures exhibited a better performance in rutting than the WMA mixtures. An increase in rutting resistance was observed with the increase in RAP percentage for HMA mixtures whereas an inconsistent trend was observed for WMA mixtures. Further study is needed to validate the use of the high percentage of RAP in Washoe County.
Yuri KALGIN; Alexander STROKIN
The problem of prediction of the service life of asphalt concrete surface constructed with modified asphalt concrete application onto a traffic lane is examined. Asphalt concrete behaviour in road surface under the traffic loads was analysed. There were shown The results of experiments and their mathematical analysis of the assessment of standard and modified cold asphalt concrete fatigue life on road surface were shown. The service life of an asphalt concrete surface covered with standard an...
Some Properties of Emulsified Asphalt Paving Mixture at Iraqi Environmental Conditions
Shakir.A.Al-Mishhadani; Hasan.H.Al-Baid
Cold emulsified asphalt mixture is generally a mix made of emulsified asphalt withaggregate. Emulsified asphalt is manufactured from base asphalt, emulsifier agent and waterwith approximate percentage of 40% to 75% asphalt, 0.1% to 2.5% emulsifier and 25% to60% water plus some minor components. This study aims to use the cold emulsified asphaltmixtures for road construction and maintenance in Iraq as an alternative to the hot asphaltmixtures, due to its economical, practical and environmental...
The first engineered self-healing asphalt road: How is it performing?
Liu, Q.; Schlangen, H.E.J.G.; Van Bochove, G.
Porous asphalt shows excellent performance in both noise reduction and water drainage. Although porous asphalt has these great qualities, its service life is much shorter (sometimes only half) compared to dense graded asphalt roads. Ravelling, which is the loss of aggregate particles from the surface layer, is the main damage mechanism of porous asphalt surface wearing courses. In this research, an induction healing approach (namely, activating the healing process of asphalt concrete through ...
Decision of National and Provincial Highway Asphalt Pavement Structure Based on Value Engineering
Yingwei Ren; Jingsong Shan
It is important that decision of asphalt pavement structure requires overall considerations of the performance and financial investment. To have asphalt pavement structure fulfilling good reliability, the asphalt pavement structure decision was researched based on value engineering theory. According to the national and provincial highway investigation data in Shandong Province during the last decade, the asphalt pavement performance attenuation rules of traffic levels and asphalt layer thickn...
Effectiveness of Micro- and Nanomaterials in Asphalt Mixtures through Dynamic Modulus and Rutting Tests
Hui Yao; Zhanping You
The objectives of this research are to use micro- and nanomaterials to modify the asphalt mixture and to evaluate the mechanical performance of asphalt mixtures. These micro- and nanomaterials, including carbon microfiber, Nanomer material, nanosilica, nonmodified nanoclay, and polymer modified nanoclay, were selected to blend with the control asphalt to improve the overall performance of the modified asphalt binders and mixtures. The microstructures of original materials and asphalt binders ...
Modeling and Simulation of Flow and Formation Damage of Asphalt-Paved Roads
M. H. Alawi; M. M. El-Qadi; M. A. El-Ameen
Porous asphalt is a standard asphalt built on aggregate storage bed which allows water to drain through it and reduces stormwater runoff. However, porosity of the porous asphalt and the storage bed may be effectively reduced due to trapping suspended solids from the water or from the asphalt damage. In this paper, we present mathematical modeling and numerical simulation of flow and damage of porous asphalt-paved roads. A mathematical model to describe the fine-particles transport carried by ...
Performance-based asphalt mixture design methodology
Ali, Al-Hosain Mansour
Today, several State D.O.T.s are being investigating the use of tire rubber with local conventional materials. Several of the ongoing investigations identified potential benefits from the use of these materials, including improvements in material properties and performance. One of the major problems is being associated with the transferability of asphalt rubber technology without appropriately considering the effects of the variety of conventional materials on mixture behavior and performance. Typically, the design of these mixtures is being adapted to the physical properties of the conventional materials by using the empirical Marshall mixture design and without considering fundamental mixture behavior and performance. Use of design criteria related to the most common modes of failure for asphalt mixtures, such as rutting, fatigue cracking, and low temperature thermal cracking have to be developed and used for identifying the "best mixture," in term of performance, for the specific local materials and loading conditions. The main objective of this study was the development of a mixture design methodology that considers mixture behavior and performance. In order to achieve this objective a laboratory investigation able to evaluate mixture properties that can be related to mixture performance, (in terms of rutting, low temperature cracking, moisture damage and fatigue), and simulating the actual field loading conditions that the material is being exposed to, was conducted. The results proved that the inclusion of rubber into asphalt mixtures improved physical characteristics such as elasticity, flexibility, rebound, aging properties, increased fatigue resistance, and reduced rutting potential. The possibility of coupling the traditional Marshall mix design method with parameters related to mixture behavior and performance was investigated. Also, the SHRP SUPERPAVE mix design methodology was reviewed and considered in this study for the development of an integrated
Microbial Life in a Liquid Asphalt Desert
Schulze-Makuch, Dirk; Antonio, Marina Resendes de Sousa; Ali, Denzil; Hosein, Riad; Song, Young C; Yang, Jinshu; Zaikova, Elena; Beckles, Denise M; Guinan, Edward; Lehto, Harry J; Hallam, Steven J
An active microbiota, reaching up to 10 E+7 cells/g, was found to inhabit a naturally occurring asphalt lake characterized by low water activity and elevated temperature. Geochemical and molecular taxonomic approaches revealed novel and deeply branching microbial assemblages mediating anaerobic hydrocarbon degradation, metal respiration and C1 utilization pathways. These results open a window into the origin and adaptive evolution of microbial life within recalcitrant hydrocarbon matrices, and establish the site as a useful analog for the liquid hydrocarbon environments on Saturn's moon Titan.
Finite element simulation of asphalt fatigue testing
DEFF Research Database (Denmark)
Ullidtz, Per; Kieler, Thomas Lau; Kargo, Anders
damage mechanics.The paper describes how continuum damage mechanics may be used with a finite element program to explain the progressive deterioration of asphalt mixes under laboratory fatigue testing. Both constant stress and constant strain testing are simulated, and compared to the actual results from...... three point and four point fatigue test on different mixes. It is shown that the same damage law, based on energy density, may be used to explain the gradual deterioration under constant stress as well as under constant strain testing.Some of the advantages of using this method for interpreting fatigue...
Evaluation of Hydrated Lime Filler in Asphalt Mixtures
Directory of Open Access Journals (Sweden)
Mohammed Abbas Hasan Al-Jumaily
Full Text Available Mineral filler is one of important materials and affecting on properties and quality of asphalt mixtures .There are different types of mineral filler depended on cost and quality , the matter encourages us to achieve this study to evaluate hydrated lime filler effects on properties of asphalt mixes related with strength and durability. Conventional asphaltic concrete mixtures with Portland cement and soft sandstone fillers and mixtures modified with hydrated lime were evaluated for their fundamental engineering properties as defined by Marshall properties , index of retained strength , indirect tensile strength , permanent deformation characteristics , and fatigue resistance .A typical dense graded mixture employed in construction of surface course pavement in Iraq in accordance with SCRB specifications was used .The materials used in this study included mineral aggregate materials (coarse and fine sizes were originally obtained from Najaf Sea quarries and two grades of asphalt cements produced from Daurah refinery which are D47 and D66 . The physical properties , stiffness modulus and chemical composition are evaluated for the recovered asphalt cement from prepared asphalt mixes containing various filler types .The paper results indicated that the addition of hydrated lime as mineral filler improved the permanent deformation characteristics and fatigue life and the use of hydrated lime will decrease the moisture susceptibility of the asphalt mixtures.
Effect of fiber types on relevant properties of porous asphalt
Institute of Scientific and Technical Information of China (English)
WU Shao-peng; LIU Gang; MO Lian-tong; CHEN Zheng; YE Qun-shan
The research was conducted to evaluate the effects of cellulose and polyester fibers on the properties of porous asphalt mixes,using the tests of draindown,abrasion,volumetric properties,rutting,and moisture damage. Images of scanning electron microscopy and X-ray computerized tomography were adopted to identify the microstructure of the fiber and inner stone skeleton of porous asphalt. The influence of rutting parameter (G*/sinδ) of asphalt modified by different fibers on the rutting resistance of the mixes was investigated. Based upon Mohr-Coulomb theory,the cohesion and the angle of internal friction of the mixes were derived from both indirect tension and unconfined compression strength. The experimental results indicate that fibers mainly stabilize asphalt binder and thicken asphalt film around aggregates. Furthermore,they result in the improved mechanical strength of porous asphalt mixes at high temperature slightly. From comparison analysis,cellulose fibers appear to perform better than polyester fibers in porous asphalt mixes.
Asphalt emulsion sealing of uranium mill tailings
International Nuclear Information System (INIS)
The use of asphalt emulsion to contain radon and radium in uranium tailings is being investigated at the Pacific Northwest Laboratory. Results of these studies indicate that a radon flux reduction of greater than 99% can be obtained using either a poured-on/sprayed-on seal (3.0 to 7.0 mm thick) or an admix seal (2.5 to 15.2 cm thick) containing about 18 wt % residual asphalt. A field test was carried out at the Grand Junction tailings pile in order to demonstrate the sealing process. A reduction in radon flux ranging from 4.5 to greater than 99% (76% average) was achieved using a 15.2 cm (6 in.) admix seal with a sprayed-on top coat. A hydrostatic stabilizer was used to apply the admix. This was followed by compaction to form the radon seal. Overburden was applied to provide a protective soil layer over the seal. Included in part of the overburden was a herbicide to prevent root penetration
Conversion of asphalt into distillate products
International Nuclear Information System (INIS)
This paper reports the conversion of asphalt in a micro-autoclave under an inert atmosphere of nitrogen to lighter products. The influence of temperature, contact time and some catalysts, i.e. clay type; UTIMAC, HZSM-5 and sodium silicate, acidic type; phospho-tungstic acid, oxide type; ammonium hepta molybdate, silica gel, nickel oxide and alumina powder, chloride type; stannous chloride and aluminum chloride and modifiers like methyl iodide and coal, on the yield of liquid and gas products was studied. A marked effect of temperature on the yield of liquid as well as gas products was observed. Employment of clay type catalysts was found to be beneficial in term of yields of liquid products. Among the catalysts used; UTIMAC clay caused the maximum conversion to desired products. The other catalysts caused a decline in the yield of desired products because of coke formation due to condensation reactions catalyzed by these catalysts. The effect of concentration in the case of clay as catalyst was also studied, and synergistic effects were observed in terms of desired product yield. The study will be helpful in planning asphalt conversion processes into light oil fractions
Asphalt as biological shielding against fusion neutrons
International Nuclear Information System (INIS)
For fusion experiments, thick biological radiation protection shields are necessary due to the deep penetration capability of the 14 MeV neutrons. A (D,T) neutron generator with a moderate output of around 1012 n/sec requires a concrete shielding of a wall thickness of 2 meters laterally and at the top of an experimental assembly. The cost for this biological shield may exceed the cost for most of the equipment for a fusion and/or hybrid experimental installation. Particularly, in Saudi Arabia, asphalt is very cheap and available in bulk quantities. As it is rich in hydrogen and carbon, it is worthwhile to investigate its shielding potential against fusion neutron. In the present work different biological shield configurations of asphalt at the wall of the experimental cavity for a research program being undertaken in Saudi Arabia, are investigated. The experimental cavity is approximated by a sphere of 5 meters radius. The yield of the neutron generator is taken as 1012 - 14 MeV - neutron/sec
Discrete Element Simulation of Asphalt Mastics Based on Burgers Model
Institute of Scientific and Technical Information of China (English)
LIU Yu; FENG Shi-rong; HU Xia-guang
In order to investigate the viscoelastic performance of asphalt mastics, a micro-mechanical model for asphalt mastics was built by applying Burgers model to discrete element simulation and constructing Burgers contact model. Then the numerical simulation of creep tests was conducted, and results from the simulation were compared with the analytical solution for Burgers model. The comparision snowed that the two results agreed well with each other, suggesting that discrete element model based on Burgers model could be employed in the numerical simulation for asphalt mastics.
Characterization of asphalt materials containing bio oil from michigan wood
Mills-Beale, Julian
The objective of this research is to develop sustainable wood-blend bioasphalt and characterize the atomic, molecular and bulk-scale behavior necessary to produce advanced asphalt paving mixtures. Bioasphalt was manufactured from Aspen, Basswood, Red Maple, Balsam, Maple, Pine, Beech and Magnolia wood via a 25 KWt fast-pyrolysis plant at 500 °C and refined into two distinct end forms - non-treated (5.54% moisture) and treated bioasphalt (1% moisture). Michigan petroleum-based asphalt, Performance Grade (PG) 58-28 was modified with 2, 5 and 10% of the bioasphalt by weight of base asphalt and characterized with the gas chromatography-mass spectroscopy (GC-MS), Fourier Transform Infra-red (FTIR) spectroscopy and the automated flocculation titrimetry techniques. The GC-MS method was used to characterize the Carbon-Hydrogen-Nitrogen (CHN) elemental ratio whiles the FTIR and the AFT were used to characterize the oxidative aging performance and the solubility parameters, respectively. For rheological characterization, the rotational viscosity, dynamic shear modulus and flexural bending methods are used in evaluating the low, intermediate and high temperature performance of the bio-modified asphalt materials. 54 5E3 (maximum of 3 million expected equivalent standard axle traffic loads) asphalt paving mixes were then prepared and characterized to investigate their laboratory permanent deformation, dynamic mix stiffness, moisture susceptibility, workability and constructability performance. From the research investigations, it was concluded that: 1) levo, 2, 6 dimethoxyphenol, 2 methoxy 4 vinylphenol, 2 methyl 1-2 cyclopentandione and 4-allyl-2, 6 dimetoxyphenol are the dominant chemical functional groups; 2) bioasphalt increases the viscosity and dynamic shear modulus of traditional asphalt binders; 3) Bio-modified petroleum asphalt can provide low-temperature cracking resistance benefits at -18 °C but is susceptible to cracking at -24 °C; 3) Carbonyl and sulphoxide
Influence of conductive additive on temperature susceptibility of asphalt binders
Institute of Scientific and Technical Information of China (English)
吴少鹏; 李波; 陈筝; 黄旭
The effects of graphite on temperature susceptibility of asphalt binders were investigated by penetration test,Ring & Ball softening point test and viscosity test.And penetration index(IP),viscosity-temperature susceptibility(SVT),and penetration-viscosity numbers(NPV) were introduced to evaluate the effects.The results show that the penetration,softening point and viscosity of asphalt binder increase with the increase of content of graphite.This means that the addition of graphite makes asphalts stiffer.The results from IP,NPV and SVT show that temperature susceptibility is reduced by the addition of graphite.
An Anisotropic Hardening Model for Springback Prediction
Zeng, Danielle; Xia, Z. Cedric
As more Advanced High-Strength Steels (AHSS) are heavily used for automotive body structures and closures panels, accurate springback prediction for these components becomes more challenging because of their rapid hardening characteristics and ability to sustain even higher stresses. In this paper, a modified Mroz hardening model is proposed to capture realistic Bauschinger effect at reverse loading, such as when material passes through die radii or drawbead during sheet metal forming process. This model accounts for material anisotropic yield surface and nonlinear isotropic/kinematic hardening behavior. Material tension/compression test data are used to accurately represent Bauschinger effect. The effectiveness of the model is demonstrated by comparison of numerical and experimental springback results for a DP600 straight U-channel test.
A review of the fundamentals of polymer-modified asphalts: Asphalt/polymer interactions and principles of compatibility.
Polacco, Giovanni; Filippi, Sara; Merusi, Filippo; Stastna, George
During the last decades, the number of vehicles per citizen as well as the traffic speed and load has dramatically increased. This sudden and somehow unplanned overloading has strongly shortened the life of pavements and increased its cost of maintenance and risks to users. In order to limit the deterioration of road networks, it is necessary to improve the quality and performance of pavements, which was achieved through the addition of a polymer to the bituminous binder. Since their introduction, polymer-modified asphalts have gained in importance during the second half of the twentieth century, and they now play a fundamental role in the field of road paving. With high-temperature and high-shear mixing with asphalt, the polymer incorporates asphalt molecules, thereby forming a swallowed network that involves the entire binder and results in a significant improvement of the viscoelastic properties in comparison with those of the unmodified binder. Such a process encounters the well-known difficulties related to the poor solubility of polymers, which limits the number of macromolecules able to not only form such a structure but also maintain it during high-temperature storage in static conditions, which may be necessary before laying the binder. Therefore, polymer-modified asphalts have been the subject of numerous studies aimed to understand and optimize their structure and storage stability, which gradually attracted polymer scientists into this field that was initially explored by civil engineers. The analytical techniques of polymer science have been applied to polymer-modified asphalts, which resulted in a good understanding of their internal structure. Nevertheless, the complexity and variability of asphalt composition rendered it nearly impossible to generalize the results and univocally predict the properties of a given polymer/asphalt pair. The aim of this paper is to review these aspects of polymer-modified asphalts. Together with a brief description of
Plasma Arc Surface Hardening Robot Technology
Institute of Scientific and Technical Information of China (English)
In national economy and national defense, a lot of ma chine components become worthless early because of wear and tear and corrode. It leads to huge loss of resource and material. Surface hardening of the steel cou ld form a hard, wearable, corrode-resisting layer on the surface to enhance the mechanical property of the machine component. From 1980s, there is a new method of surface hardening that is heating with plasma arc. It overcomes the shortage of old methods and is adopted in automotive product ...
Investigation of Hardened Filling Grout Samples
DEFF Research Database (Denmark)
Sørensen, Eigil V.
Suzlon Wind Energy A/S requested on August 28, 2007 an investigation of 2 samples of a hardened filling grout to be carried out, comprising drilling and strength determination of 4 test cylinders, and description of the surface characteristics of the samples....... Suzlon Wind Energy A/S requested on August 28, 2007 an investigation of 2 samples of a hardened filling grout to be carried out, comprising drilling and strength determination of 4 test cylinders, and description of the surface characteristics of the samples....
A novel radiation hardened by design latch
Institute of Scientific and Technical Information of China (English)
Huang Zhengfeng; Liang Huaguo
Due to aggressive technology scaling, radiation-induced soft errors have become a serious reliability concern in VLSI chip design. This paper presents a novel radiation hardened by design latch with high single-event-upset (SEU) immunity. The proposed latch can effectively mitigate SEU by internal dual interlocked scheme. The propagation delay, power dissipation and power delay product of the presented latch are evaluated by detailed SPICE simulations. Compared with previous SEU-hardening solutions such as TMR-Latch, the presented latch is more area efficient, delay and power efficient. Fault injection simulations also demonstrate the robustness of the presented latch even under high energy particle strikes.
信息动态%A Research on the Pavement Performance of Warm Mix Buton Mastic Asphalt
Institute of Scientific and Technical Information of China (English)
Compositing modified asphalt mixture is a kind of asphalt mixture which uses Buton Mastic Asphalt(BMA) and warm modifier compound modification. It is proved that the composite modified asphalt mixture technology can greatly reduce the mixing temperature, save energy and protect the environment, and can guarantee good road performance. Employing Buton Mastic Asphalt as modifier can obviously increase the high temperature stability of asphalt mixture, with little impact on low temperature performance.
Rutting Resistance of Asphalt Overlay with Multilayer Wheel Tracking Test
Institute of Scientific and Technical Information of China (English)
LIAO Weidong; CHEN Zheng; WU Shaopeng; MO Liantong; LIU Gang
The rutting resistance of multilayer asphalt overlay was researched by using laboratory wheel tracking test. The effects of loading level and test temperature on rutting resistance of asphalt overlay structure were evaluated by means of multilayer specimens .In comparison with multilayer tests, standard specimens of various layers were also conducted to evaluate the rutting resistance. Experimental results indicated that the test temperature and applied load have a significant effect on rutting resistance of asphalt concrete. Higher test temperature and heavier applied load resulted in higher rut depths. In addition, the mutilayer wheel tracking test has been demonstrated to be a more reasonable solution in evaluation on rutting resistance of asphatt pavement structure beasuse it reflects the cumulative permanent deformation in all of asphalt layers.
Performance Characterization of Polymer Modified Asphalt Binders and Mixes
Directory of Open Access Journals (Sweden)
Nikhil Saboo
Full Text Available Fatigue sensitivity of four different asphalt binders and three different asphalt mixes was evaluated in the study. Binders were subjected to Linear Amplitude Sweep (LAS test at three temperatures of 10, 20, and 30°C. Four-point beam bending test (4PBBT was conducted on the asphalt mixes at a temperature of 20°C for strain amplitudes varying from 200 to 1000 microstrains. Tests like retained Marshall Stability and indirect tensile strength (ITS were also carried out to judge the mix performance. Experimental studies demonstrated that elastomeric modified binder and mixes gave the best performance in fatigue. Plastomeric modification was found to be highly strain susceptible and resulted in poor fatigue performance. The fatigue life of stone mastic asphalt (SMA was found to be almost five times higher than the dense graded mixes. For similar strain levels, the results of LAS test could be linearly correlated with the 4PBBT results.
Storm Water General Permit 3 for Rock and Asphalt
Iowa State University GIS Support and Research Facility — General permit #3 for storm water discharges associated with industrial activity for Asphalt Plants, Concrete Batch Plants, Rock Crushing Plants and Construction...
Effect of moisture on the aging behavior of asphalt binder
Ma, Tao; Huang, Xiao-Ming; Mahmoud, Enad; Garibaldy, Emil
The moisture aging effect and mechanism of asphalt binder during the in-service life of pavement were investigated by laboratory simulating tests. Pressure aging vessel (PAV) test simulating the long-term aging of binder during the in-service life of pavement was modified to capture the long-term moisture aging effect of binder. Penetration grade tests including penetration test, soften point test, and ductility test as well as Superpave™ performance grade tests including viscosity test, dynamic shear rheometer test, and bending beam rheometer test were conducted to fully evaluate the moisture aging effect of binder. Fourier transform infrared spectroscopy test and Gel-permeation chromatography test were applied to provide a fundamental understanding of the moisture aging mechanism of binder. The results indicate that moisture condition can accelerate the aging of asphalt binder and shorten the service life of asphalt binder. The modified PAV test with moisture condition can well characterize the moisture aging properties of asphalt binder.
Building Asphalt Pavement with SBS-based Compound Added Using a Dry Process in Greenland
DEFF Research Database (Denmark)
Lee, Hosin; Kim, Yongjoo; Geisler, Nivi;
-based compound seemed to affect the asphalt mix to become more flexible under the heavy loads. By adding SBS-based compound to asphalt mixtures using a "dry" process, it is expected that the pavement would become more resistant to rutting than a typical asphalt mixture used in Greenland while enduring its arctic...... PMA where it is formulated to melt and blend with asphalt quickly during a batch mixing process. The main objectives of this study are to (1) build asphalt pavement using asphalt mixtures with SBS-based compound added using a "dry" process at the batch plant and (2) evaluate its performance under...
Firdaus Chairuddin*, Wihardi Tjaronge
The test Indirect Tensile Strength for asphalt quality 3%, 4%, 5% are 0.0673, 0.325, 0.2370 subsequently. Cantabro test, loss weight for asphalt quality 3%, 4%, 5% are 77.10, 14.56, 9.70 subsequently. Coefficient vertical test permeability 0.1795 for asphalt 3%, 0.2029 for asphalt 4%, and 0.1596 for asphalt 5%, Unconfined Compressive Strength, Modulus elasticity 146.543 and ratio poisson 0.095831 for asphalt 3%, Modulus elasticity 91.450 and Ratio poisson 0.20600...
Performance of Recycled Porous Hot Mix Asphalt with Gilsonite Additive
Ludfi Djakfar; Hendi Bowoputro; Bangun Prawiro; Nugraha Tarigan
The objective of the study is to evaluate the performance of porous asphalt using waste recycled concrete material and explore the effect of adding Gilsonite to the mixture. As many as 90 Marshall specimens were prepared with varied asphalt content, percentage of Gilsonite as an additive, and proportioned recycled and virgin coarse aggregate. The test includes permeability capability and Marshall characteristics. The results showed that recycled concrete materials seem to have a potential...
Modified rubberized stone matrix asphalt for Nineveh roads
Institute of Scientific and Technical Information of China (English)
Al-Hadidy AI; TAN Yi-qiu
To evaluate the effects of Crumb Rubber Modifiers (CRMS) on basic engineering properties (i. e.Marshall, tensile strength, and compressive strength) of stone matrix asphalt mixtures, the ASTM testing and procedures were employed. Results of the evaluation were used to quantify the effect of CRM source and CRM content on engineering properties at testing temperatures of 25℃and 60℃. Statistical models were developed, which represent the nature of effects on performance-related properties of stone matrix asphalt mixtures.
Preparation of Flame Retardant Modified with Titanate for Asphalt Binder
Improving the compatibility between flame retardant and asphalt is a difficult task due to the complex nature of the materials. This study explores a low dosage compound flame retardant and seeks to improve the compatibility between flame retardants and asphalt. An orthogonal experiment was designed taking magnesium hydroxide, ammonium polyphosphate, and melamine as factors. The oil absorption and activation index were tested to determine the effect of titanate on the flame retardant additive...
Mechanistic and Economical Characteristics of Asphalt Rubber Mixtures
Mena I. Souliman; Annie Eifert
Load associated fatigue cracking is one of the major distress types occurring in flexible pavement systems. Flexural bending beam fatigue laboratory test has been used for several decades and is considered to be an integral part of the new superpave advanced characterization procedure. One of the most significant solutions to prolong the fatigue life for an asphaltic mixture is to utilize flexible materials as rubber. A laboratory testing program was performed on a conventional and Asphalt Ru...
The temperature effect on the reflective cracking of asphalt overlays
Minhoto, Manuel; Pais, Jorge; Pereira, Paulo
This paper presents a study about the influence of temperature on the reflective cracking in a flexible road pavement through the evaluation of the asphalt overlay damage associated to traffic and temperature variations throughout a year. This study was developed from a numerical simulation of the asphalt overlay behaviour based on a three-dimensional finite-element analysis, considering the simultaneous loading of traffic and temperature variations. A mechanistic-based overlay design method ...
Effect of base bitumen composition on asphalt rubber binder properties
Partl, M.N.; Ould-Henia, M.; Dumont, A.-G.
The asphalt rubber blend properties are strongly related to its base components properties. The base bitumen composition is considered as a key factor influencing the final rheological properties of asphalt rubber binder. This paper describes results from a laboratory investigation of the interaction between crumb rubber and different composition bitumen according to the wet process. The bitumen composition is determined according to the SARA decomposition approac...
Asphalt in carbon-14-dated archaeological samples from Terqa, Syria
International Nuclear Information System (INIS)
The results are reported of an organic geochemical study to verify contamination in 14C dated archaeological samples, which could account for much older apparent ages than expected. The data indicate that ancient asphalt must be the source of contamination, showing that caution should be exercised, in interpreting 14C dates of archaeological samples from areas containing asphalt or other fossil fuel deposits. (U.K.)
Asphalt Carriers from Kraljevica Shipyard – Constructional and Technological Aspects
Grubišić, R.
After presenting the design development of the asphalt carrier Asphalt Seminole and her sister-ships in the article published in the previous issue of Brodogradnja (No. 1/2006), in this article the structural analysis made in the design stage and some constructional and technological specifities during the building stage are presented. Special emphasis is given to the presentation of the structional connection between the hull and the cargo tanks with the description of the elastic vertical s...
Resistivity-temperature Characteristics of Conductive Asphalt Concrete
Institute of Scientific and Technical Information of China (English)
SUN Wenzhou; LI Xu; YANG Qun; ZHANG Hongwei
The changes of resistivity of conductive asphalt concrete at different temperatures were studied, and positive temperature coefficient (PTC) model was established to estimate the influence of temperature on the resistivity quantitatively, which eliminated the interference with conductivity evaluation brought by temperature variation. Finally, the analysis of temperature cycling test results proves that the changes of percolation network structure caused by temperature variation prompt the emergence of PTC of conductive asphalt concrete.
Directory of Open Access Journals (Sweden)
Imad Al-Shalout
Full Text Available This study deals with the durability of asphalt concrete, including the effects of different gradations, compaction temperatures and immersion time on the durability potential of mixtures. The specific objectives of this study are: to investigate the effect of compaction temperature on the mechanical properties of asphalt concrete mixtures; investigate the effect of bitumen content and different aggregate gradations on the durability potential of bituminous mixtures.
HTPro: Low-temperature Surface Hardening of Stainless Steel
DEFF Research Database (Denmark)
Christiansen, Thomas Lundin; Somers, Marcel A. J.
Low-temperature surface hardening of stainless steel provides the required performance properties without affecting corrosion resistance.......Low-temperature surface hardening of stainless steel provides the required performance properties without affecting corrosion resistance....
Feasibility Studies on Underwater Laser Surface Hardening Process
Directory of Open Access Journals (Sweden)
Biao Jin
Full Text Available Laser surface hardening process is a very promising hardening method for ferrous and nonferrous alloys where transformations occur during cooling after laser melting in the solid state. This study experimentally characterizes laser surface hardening of tool steel in both water and air. For the underwater operation, laser surface scanning is performed over the tool steel surface which is immersed in water. The laser surface hardening tests are performed with a maximum 200 W fiber laser with a Gaussian distribution of energy in the beam. For the surface hardening, single-track melting experiment which sequentially scans elongated path of single line has been performed. As the hardened depth depends on the thermal conductivity of the material, the surface temperature and the penetration depth may be varied by underwater laser processing. The feasibility of underwater laser surface hardening process is discussed on the basis of average hardness level and hardened bead shape.
Vanpaemel, J.
The knowledge of the hardening phenomenon was achieved through a very cumulative process without any discontinuity or 'scientific crisis' . The history of the hardening shows a definite interrelationship between technological approach (or the application-side) and academic science .
Effects of Fibers on the Dynamic Properties of Asphalt Mixtures
Institute of Scientific and Technical Information of China (English)
The dynamic characteristics of fiber-modified asphalt mixture were investigated. Cellulose fiber, polyester fiber and mineral fiber were used as additives for asphalt mixture, and the dosage was 0.3%, 0.3%,0.4%, respectively. Dynamic modulus test using SuperPave simple performance tester (SPT) was conducted to study the dynamic modulus (E*) and phase angle (δ) for the control asphalt mixture and fiber-modified ones at various temperatures and frequencies. Experimental results show that all fiber-modified asphalt mixtures have higher dynamic modulus compared with control mixture. The dynamic modulus master curves of each type of asphalt mixtures are determined based on nonlinear least square regression in accordance with the timetemperature superposition theory at a control temperature (21.1 ℃). The fatigue parameter E*×sinδ and rutting parameter E*/sinδ of asphalt mixture are adopted to study the fatigue and rutting-resistance properties, and experimental results indicate that such properties can be improved by fiber additives.
Application of Common Mid-Point Method to Estimate Asphalt
Zhao, Shan; Al-Aadi, Imad
3-D radar is a multi-array stepped-frequency ground penetration radar (GPR) that can measure at a very close sampling interval in both in-line and cross-line directions. Constructing asphalt layers in accordance with specified thicknesses is crucial for pavement structure capacity and pavement performance. Common mid-point method (CMP) is a multi-offset measurement method that can improve the accuracy of the asphalt layer thickness estimation. In this study, the viability of using 3-D radar to predict asphalt concrete pavement thickness with an extended CMP method was investigated. GPR signals were collected on asphalt pavements with various thicknesses. Time domain resolution of the 3-D radar was improved by applying zero-padding technique in the frequency domain. The performance of the 3-D radar was then compared to that of the air-coupled horn antenna. The study concluded that 3-D radar can be used to predict asphalt layer thickness using CMP method accurately when the layer thickness is larger than 0.13m. The lack of time domain resolution of 3-D radar can be solved by frequency zero-padding. Keywords: asphalt pavement thickness, 3-D Radar, stepped-frequency, common mid-point method, zero padding.
Reinforcement of Recycled Foamed Asphalt Using Short Polypropylene Fibers
Directory of Open Access Journals (Sweden)
Yongjoo Kim
Full Text Available This paper presents the reinforcing effects of the inclusion of short polypropylene fibers on recycled foamed asphalt (RFA mixture. Short polypropylene fibers of 10 mm length with a 0.15% by weight mixing ratio of the fiber to the asphalt binder were used. The Marshall stability test, the indirect tensile strength test, the resilient modulus test, and wheel tracking test of the RFA mixtures were conducted. The test results were compared to find out the reinforcing effects of the inclusion of the fiber and the other mixtures, which included the conventional recycled foamed asphalt (RFA mixtures; the cement reinforced recycled foamed asphalt (CRFA mixtures; the semihot recycled foamed asphalt (SRFA mixtures; and recycled hot-mix asphalt (RHMA mixtures. It is found that the FRFA mixture shows higher Marshall stability than the RFA and SRFA mixtures, higher indirect tensile strength than the RFA mixture, and higher rut resistance than the RFA, SRFA, and RHMA mixtures as seen from the wheel tracking test.
Rheological properties of asphalt mixtures containing various fibers
Institute of Scientific and Technical Information of China (English)
叶群山; 吴少鹏; 陈筝; 刘至飞
Rheological characteristics of fiber-modified asphalt mixture were investigated.Cellulous fiber,polyester fiber and mineral fiber were used as additives for asphalt mixture,and the dosages were 0.3%,0.3%,0.4%,respectively.Dynamic modulus test using superpave simple performance tester(SPT) was adopted to study the dynamic modulus and phase angle for the control mixture and fiber-modified ones at various temperatures and frequencies.Test results show that the rheological properties can be improved significantly by the addition of various fibers.The dynamic modulus increases with the increase of frequency,and the phase angle decreases with the increase of frequency.When various fibers are used,the dynamic modulus increases and phase angle decreases at each frequency.This indicates that the stiffness and the elastic portion of fiber-modified asphalt mixtures can be enhanced when various fibers are used,which results in the change of viscoelastic properties of mixtures.The creep test results show that the total strain and the permanent strain of asphalt mixtures during load-unload cycle can be significantly reduced,which results in the improvement of resistance to permanent deformation for asphalt mixtures containing various fiber additives.The Burgers model can be employed effectively to illustrate the rheological properties of fiber modified asphalt mixtures.
DEFF Research Database (Denmark)
The invention relates to case-hardening of a stainless steel article by means of gas including carbon and/or nitrogen, whereby carbon and/or nitrogen atoms diffuse through the surface into the article. The method includes activating the surface of the article, applying a top layer on the activated...
Instabilities in power law gradient hardening materials
DEFF Research Database (Denmark)
Niordson, Christian Frithiof; Tvergaard, Viggo
Tension and compression instabilities are investigated for specimens with dimensions in the micron range. A finite strain generalization of a higher order strain gradient plasticity theory is implemented in a finite element scheme capable of modeling power law hardening materials. Effects...
Additive strengthening mechanisms in dispersion hardened polycrystals
DEFF Research Database (Denmark)
Hansen, Niels; Ralph, B.
Tensile data from polycrystalline samples of copper dispersion strengthened by alumina are analysed. The basis of this analysis is to look at the strain range from 0.05 to 0.20 where the stress-strain curves show a parabolic hardening behaviour and are parallel to one another. The means by which...
Shimazaki, Masaru; Tsunoo, Takashi; Kasahara, Atsushi
The low temperature properties improvement asphalt that is no decreasing the transformation follow and the stress relaxation properties at the low temperature was developed. It aimed at properties of PG64-28 (lowest temperature 28 degree C and maximum temperature 64 degree C that was able to be used) from PG (Performance Grade) of mix design method SUPERPAVE (Superior Performance Pavement) of new road-building plan SHRP (Strategic Highway Research Program) in the United States when developing. When the repair work of the rock fill dam with asphalt facing located in Kyogoku-cho Abuta-gun Hokkaido was planned, the applicability of the developed asphalt was verified. As for the verification outcome and the developed asphalt, it was proven that it was applied to the repair construction, and there was no problem in manufacturing and construction.
Cryptographic Path Hardening: Hiding Vulnerabilities in Software through Cryptography
Ganesh, Vijay; Carbin, Michael; Rinard, Martin
We propose a novel approach to improving software security called Cryptographic Path Hardening, which is aimed at hiding security vulnerabilities in software from attackers through the use of provably secure and obfuscated cryptographic devices to harden paths in programs. By "harden" we mean that certain error-checking if-conditionals in a given program P are replaced by equivalent" we mean that adversaries cannot use semi-automatic program analysis techniques to reason about the hardened pr...
Feasibility Studies on Underwater Laser Surface Hardening Process
Biao Jin; Min Li; TaeWoo Hwang; YoungHoon Moon
Laser surface hardening process is a very promising hardening method for ferrous and nonferrous alloys where transformations occur during cooling after laser melting in the solid state. This study experimentally characterizes laser surface hardening of tool steel in both water and air. For the underwater operation, laser surface scanning is performed over the tool steel surface which is immersed in water. The laser surface hardening tests are performed with a maximum 200 W fiber laser with a ...
Replacement of asphalt in glass-mat roofing shingles. Final report, March 1980-March 1982
Energy Technology Data Exchange (ETDEWEB)
Bastian, E.J. Jr.; McCandlish, E.F.K.; Sieling, F.W.
Up to 50% of the asphalt now used in glass-mat shingles may be replaceable by increasing the mineral filler content and/or extending the asphalt with elemental sulfur. Highly filled, lab-made shingles containing asphalt flux perform acceptably in fire tests, slide tests, blister tests, granule adhesion, and freeze-thaw cracking tests. They have high stain and scuff potential and are too limp for convenient application around 110/sup 0/F. Lab-made shingles containing asphalt saturant are satisfactory in most respects, but they are still too limp for high temperature application. Various methods to stiffen highly filled shingles were tried. The most promising method is the use of two lightweight glass mats, laminated together with asphalt. Shingles made in this way have handling properties superior to conventional shingles and are economically feasible. In the area of replacement of asphalt with sulfur, five small-scale plant trials produced shingles which, after a year of outdoor exposure, are satisfactory. On the basis of preliminary measurements, no important difference in tensile or flexural properties between asphalt and sulfur/asphalt shingles is expected. In Weather-Ometer tests, sulfur/asphalt tends to have lower durability than conventional coating. This is confirmed by outside weathering of sulfur/asphalt films. By choosing the correct asphalt softening point and correct filler level, sulfur/asphalt/filler can have equal durability to conventional asphalt/filler combinations.
A New Method of Hardening Inner Wall of Long Pipe
Institute of Scientific and Technical Information of China (English)
A new laser inner wall hardening method for long pipe mas introduced. The system combines laser surface hardening with robot moving in pipeline. Some craft experiments have been done with this system and optimum parameters of laser hardening have been found.
Professionalising the asphalt construction process: aligning information technologies, operators' knowledge and laboratory practices
Bijleveld, Frank Roland
This research addresses the need to professionalise the asphalt construction process. A distinctive action research strategy is designed and carried out to progressively improve operational strategies of asphalt teams from technological, human (operator) and laboratory perspectives. Using informatio
The Effect of Joint Width on Structural Performance of Asphalt Block Pavements
Directory of Open Access Journals (Sweden)
Ahmed Abdelgalil
Full Text Available Asphalt blocks have been occasionally used around the world as a road pavement, but there have been very limited studies being done to evaluate the effect of joint width (spacing between the blocks on the structural performance of asphalt paving blocks. This study explains the experimental study to assess the performance and properties of asphalt paving blocks laid with different joint widths between the blocks i.e., 0, 2 and 3 mm, respectively. A total of 250 asphalt paving blocks was manufactured and tested in the laboratory to ascertain the density, air voids, the compressive strength and the rut depth and displacement occurred in asphalt paving block. The design compressive load of single asphalt paving block is 166 kN. The test results showed that the joint width plays a vital role on the performance of asphalt block pavement. Asphalt paving blocks were laid as closely in contact as possible (0 mm yields the best structural performance.
The road that's taken : Alberta's bitumen and the world of asphalt
International Nuclear Information System (INIS)
Approximately one third of the bitumen produced by the oil sands industry in Canada is used as asphalt in roads and roofing materials. Crude oils used for asphalt production require very little refining. The asphalt market has become a key profit centre for some Cold Lake operators. Imperial Oil has established a research centre devoted to asphalt production at its Sarnia-based refinery. A decline in heavy oil supplies from Mexico and Venezuela has left Canada with a larger margin of the asphalt market. Industry leaders predict that demand for asphalt products will grow by 2.6 per cent per year. A sharp increase in asphalt prices led to many construction delays in 2007. Trials are now being conducted on a new warm mix paving technology that allows users to lower the temperature of asphalt by 20 to 30 degrees C when paving. 2 figs
Physico-mechanical properties of asphalt concrete based on road bitumen modified by rapeseed oil epoxide
Nykypanchuk, Mykhailo; Hrynchuk, Yurii; Olchovyk, Mykola
The investigation results of type B fine asphalt concrete and its form modified by rapeseed oil epoxide are represented. The efficiency of ERO addition and its positive effect on the physico-mechanical properties of asphalt concrete has been established.
Asphalt Roofing Shingles Into Energy Project Summary Report
Energy Technology Data Exchange (ETDEWEB)
Jameson, Rex, PE
Based on a widely cited September, 1999 report by the Vermont Agency of Natural Resources, nearly 11 million tons of asphalt roofing shingle wastes are produced in the United States each year. Recent data suggests that the total is made up of about 9.4 million tons from roofing tear-offs and about 1.6 million tons from manufacturing scrap. Developing beneficial uses for these materials would conserve natural resources, promote protection of the environment and strengthen the economy. This project explored the feasibility of using chipped asphalt shingle materials in cement manufacturing kilns and circulating fluidized bed (CFB) boilers. A method of enhancing the value of chipped shingle materials for use as fuel by removing certain fractions for use as substitute raw materials for the manufacture of new shingles was also explored. Procedures were developed to prevent asbestos containing materials from being processed at the chipping facilities, and the frequency of the occurrence of asbestos in residential roofing tear-off materials was evaluated. The economic feasibility of each potential use was evaluated based on experience gained during the project and on a review of the well established use of shingle materials in hot mix asphalt. This project demonstrated that chipped asphalt shingle materials can be suitable for use as fuel in circulating fluidized boilers and cement kilns. More experience would be necessary to determine the full benefits that could be derived and to discover long term effects, but no technical barriers to full scale commercial use of chipped asphalt shingle materials in these applications were discovered. While the technical feasibility of various options was demonstrated, only the use of asphalt shingle materials in hot mix asphalt applications is currently viable economically.
Study on Process for Manufacturing Heavy Traffic Asphalt from Gudong Crude
Institute of Scientific and Technical Information of China (English)
Wang Zijun; Long Jun; She Yucheng
The Gudong crude from Gudao oil-bearing region in the Shengli oilfield was used as the target for studying the process of manufacturing heavy traffic road asphalt. The heavy traffic road asphalt products can be made from Gudong crude through blending residuum from mild thermal conversion of vacuum resid with extract, blending the deoiled asphalt from VR propane deasphalting with vacuum resid and the extract, and blending of oxidizedhard asphalt originated from VR with the extract.
Optimization of asphalt rubber hot mixes based on performance laboratory tests
Neto, Silvrano Adonias Dantas; Farias, Márcio Muniz de; Pais, Jorge C.; Pereira, Paulo A. A.
Asphalt binders modified with crumb rubber recycled from ground tires have been successfully used in asphalt mixtures improving the mechanical and functional behaviour of the pavements. This paper shows the influence of several factors that affect the behaviour of asphalt-rubber (AR) and of hot mixes made with this material. Modified binders were prepared using a straight binder with 35/50 penetration and rubber obtained by the environmental process. Samples of asphalt-rubber w...
Visualizing asphalt roller trajectories in context: acquiring, processing, and representing sensor readings
Vasenev, Alexandr Nikolajevitsj
The asphalt compaction process relies heavily on the skills and knowledge of roller operators who act alongside other stakeholders involved in asphalt paving. It is essential that these construction specialists: (1) are adequately informed about the initial temperature distribution of the asphalt layer – an essential context factor of asphalt compaction; and (2) have the possibility to improve their knowledge by reflecting on the already-conducted and alternative compaction strategies. Both t...
SGC Tests for Influence of Material Composition on Compaction Characteristic of Asphalt Mixtures
Qun Chen; Yuzhi Li
Compaction characteristic of the surface layer asphalt mixture (13-type gradation mixture) was studied using Superpave gyratory compactor (SGC) simulative compaction tests. Based on analysis of densification curve of gyratory compaction, influence rules of the contents of mineral aggregates of all sizes and asphalt on compaction characteristic of asphalt mixtures were obtained. SGC Tests show that, for the mixture with a bigger content of asphalt, its density increases faster, that there is a...
Research on the relationship between water stability and aggregate gradation of asphalt pavement
Zhao Bing; Zhao Bo
In the early destruction of asphalt pavement, water damage is the most major form.In this paper, experimental study was conducted on the composition of asphalt concrete,Marshall specimens were made in different types of aggregate gradation with the same kind of asphalt. Water immersion tests were conducted in order to analysis the relationship between the water stability and aggregate gradation of asphalt pavement.
S. I. Buldakov; A. Yu. Dedyukhin
Problem statement. The issues of technology of preparation of dispersed rein-forced asphalt concrete mixtures are still not clearly understood. Available tech-nologies of dispersed reinforcement involve application of granulated additives, which permits the quality of asphalt concrete mixtures to be improved and, there-fore, it will result in increasing life expectancy of asphalt concrete pavements.Results and conclusions. The ways of improvement of quality and durability of asphalt-concrete ...
Design of open graded friction courses with sulfur extended asphalt binders
Saylak, D.; Ho, K. K.; Gallaway, B. M.; Little, D. N.
The combination of the anticipated shortage of asphalt cement and the projected abundance of sulfur has led to the investigation of the potential for substituting this element for the former in the paving industry. Sulfur was incorporated with asphalt to form sulfur-extended asphalt (SEA) binders for use in open graded friction course mixtures. The experimental design variable included aggregated type, asphalt cement, level of sulfur contents in the binder and method of preparing SEA binders.
Survey of microbial degradation of asphalts with notes on relationship to nuclear waste management
International Nuclear Information System (INIS)
A survey has been made of the microbial degradation of asphalts. Topics covered include chemical and physical properties of asphalts, their chemical stability, methods of demonstrating their microbial degradation, and environmental extremes for microbial activity based on existing literature. Specific concerns for the use of asphalt in nuclear waste management, plus potential effects and consequences thereof are discussed. 82 references
Preparation and Performance of Asphalt Compound Modified with Waste Crumb Rubber and Waste Polyethylene
Directory of Open Access Journals (Sweden)
Yuqiao Yang
Full Text Available Three kinds of modified asphalt were prepared by adding waste crumb rubber (WCR, waste polyethylene (WPE, and WCR/WPE to base asphalt, respectively. The influence of different doses on the performance of modified asphalt, such as 25°C penetration, softening point, 5°C ductility, and 135°C, 165°C viscosity, was studied, and the modification mechanism of modified asphalt was discussed through the fluorescence microscope. As the waterproofing materials, the waterproofness of WCR/WPE compound modified asphalt was tested. The results show that the WPE modified asphalt has excellent resistance to high temperature and WCR modified asphalt has good low temperature resistance. The resistance to deformation ability of WPE modified asphalt is better than that of the WCR modified asphalt. The 135°C viscosity of compound modified asphalt is better than that of WPE and WCR modified asphalt. In addition, the waterproofness of compound modified asphalt using waterproofing materials is better than that of common waterproofing materials.
Asphalt Inst., College Park, MD.
On the representative volume element of asphalt concrete at low temperature
Marasteanu, Mihai; Cannone Falchetto, Augusto; Velasquez, Raul; Le, Jia-Liang
The feasibility of characterizing asphalt mixtures' rheological and failure properties at low temperatures by means of the Bending Beam Rheometer (BBR) is investigated in this paper. The main issue is the use of thin beams of asphalt mixture in experimental procedures that may not capture the true behavior of the material used to construct an asphalt pavement.
Specifications and Construction Methods for Asphalt Concrete and Other Plant-Mix Types, 3rd Edition.
Asphalt Inst., College Park, MD.
The purpose of this publication is to assist engineers in the analysis, design and control of paving projects that use asphalt concrete and other asphalt plant-mixes. The scope of this new third edition has been enlarged, and changes necessitated by advances in asphalt technology have been incorporated. Chapters I and II and Appendices A and B…
40 CFR Table 2 of Subpart Aaaaaaa... - Emission Limits for Asphalt Roofing Manufacturing (Coating) Operations
... Manufacturing (Coating) Operations 2 Table 2 of Subpart AAAAAAA of Part 63 Protection of Environment... Pollutants for Area Sources: Asphalt Processing and Asphalt Roofing Manufacturing Other Requirements and... AAAAAAA of Part 63—Emission Limits for Asphalt Roofing Manufacturing (Coating) Operations For * * *...
Construction procedures using self hardening fly ash
Thornton, S. I.; Parker, D. G.
Fly ash produced in Arkansas from burning Wyoming low sulfur coal is self-hardening and can be effective as a soil stabilizing agent for clays and sands. The strength of soil-self hardening fly ash develops rapidly when compacted immediately after mixing. Seven day unconfined compressive strengths up to 1800 psi were obtained from 20% fly ash and 80% sand mixtures. A time delay between mixing the fly ash with the soil and compaction of the mixture reduced the strength. With two hours delay, over a third of the strength was lost and with four hours delay, the loss was over half. Gypsum and some commercial concrete retarders were effective in reducing the detrimental effect of delayed compaction. Adequate mixing of the soil and fly ash and rapid compaction of the mixtures were found to be important parameters in field construction of stabilized bases.
Radiation hardening revisited: Role of intracascade clustering
DEFF Research Database (Denmark)
Singh, B.N.; Foreman, A.J.E.; Trinkaus, H.
Experimental observations related to the initiation of plastic deformation in metals and alloys irradiated with fission neutrons have been analyzed. The experimental results, showing irradiation-induced increase in the upper yield stress followed by a yield drop and plastic instability, cannot...... be explained in terms of conventional dispersed-barrier hardening because (a) the grown-in dislocations are not free, and (b) irradiation-induced defect clusters are not rigid indestructible Orowan obstacles. A new model called 'cascade-induced source hardening' is presented where glissile loops produced...... been estimated and is found to be in good agreement with the measured increase in the initial yield stress in neutron irradiated copper. (C) 1997 Elsevier Science B.V....
Radiation-hardened transistor and integrated circuit
Energy Technology Data Exchange (ETDEWEB)
Ma, Kwok K. (Albuquerque, NM)
A composite transistor is disclosed for use in radiation hardening a CMOS IC formed on an SOI or bulk semiconductor substrate. The composite transistor has a circuit transistor and a blocking transistor connected in series with a common gate connection. A body terminal of the blocking transistor is connected only to a source terminal thereof, and to no other connection point. The blocking transistor acts to prevent a single-event transient (SET) occurring in the circuit transistor from being coupled outside the composite transistor. Similarly, when a SET occurs in the blocking transistor, the circuit transistor prevents the SET from being coupled outside the composite transistor. N-type and P-type composite transistors can be used for each and every transistor in the CMOS IC to radiation harden the IC, and can be used to form inverters and transmission gates which are the building blocks of CMOS ICs.
Induction surface hardening of hard coated steels
DEFF Research Database (Denmark)
Pantleon, Karen; Kessler, Olaf; Hoffmann, Franz;
. The effect of induction surface hardening on the properties of the coating-substrate-systems is mainly characterized using investigations of microstructure and chemical composition as well as measurements of hardness and residual stresses in dependence on the distance from the surface. Furthermore......The deposition of hard coatings with CVD-processes is commonly used to improve the wear resistance e.g. of tool steels in forming. The advantages of CVD are undisputed (high deposition rates with simple equipment, excellent coating properties). Nevertheless, the disadvantage of the CVD......-process is the high deposition temperature, consequently the properties of steel substrates are negatively influenced. Therefore, a subsequent heat treatment of the coated steels is necessary to restore the properties of steels ready for operation. Induction surface hardening is used as a method of heat treatment...
Image analysis of aggregate,mastic and air void phases for asphalt mixture%Image analysis of aggregate, mastic and air void phases for asphalt mixture
Institute of Scientific and Technical Information of China (English)
ADHIKARI Sanjeev; YOU Zhan-ping; HAO Pei-wen; WANG Hai-nian
The shape characterization and spatial distribution of aggregate,mastic and air void phases for asphalt mixture were analyzed.Three air void percentage asphalt mixtures,4%,7% and 8%,respectively,were cut into cross sections and polished.X-ray scanning microscope was used to capture aggregate,mastic,air void phase by the image.The average of polygon diameter was chosen as a threshold to determine which aggregates would be retained on a given sieve.The aggregate morphological image from scanned image was utilized by digital image processing method to calculate the gradation of aggregate and simulate the real gradation.Analysis result shows that the air void of asphalt mixture has influence on the correlation between calculation gradation and actual gradation.When comparing 4.75 mm sieve size of 4%,7% and 8% air void asphalt mixtures,7% air void asphalt mixture has 55% higher than actual size gradation,8% air void asphalt mixture has 8% higher than actual size gradation,and 4% air void asphalt mixture has 3.71% lower than actual size gradation.4% air void asphalt mixture has the best correlation between calculation gradation and actual gradation comparing to other specimens.The air void percentage of asphalt mixture has no obvious influence on the air void orientation,and three asphalt mixtures show the similar air orientation along the same direction.4 tabs,7 figs,17 refs.
Radiation-chemical hardening of epoxyoligoesteracrylates
International Nuclear Information System (INIS)
The paint and varnish epoxide compositions radiation-hardened with the following warm-up (γ-radiation of 60%, dose rate 1 Gy/s; accelerated electrons, dose rate 1.7 kGy/s) are obtained. Therewith both methods of epoxy group inclusions into a three-dimensional net are coincided: preliminary epoxy resin modification by methacrylic acid and inclusion ternary amine into compositions. Physicomechanical and electric characteristics of oligomeric compositions are presented
Beam hardening correction algorithm in microtomography images
Energy Technology Data Exchange (ETDEWEB)
Sales, Erika S.; Lima, Inaya C.B.; Lopes, Ricardo T., E-mail: firstname.lastname@example.com, E-mail: email@example.com [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Lab. de Instrumentacao Nuclear; Assis, Joaquim T. de, E-mail: email@example.com [Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Inst. Politecnico. Dept. de Engenharia Mecanica
Quantification of mineral density of bone samples is directly related to the attenuation coefficient of bone. The X-rays used in microtomography images are polychromatic and have a moderately broad spectrum of energy, which makes the low-energy X-rays passing through a sample to be absorbed, causing a decrease in the attenuation coefficient and possibly artifacts. This decrease in the attenuation coefficient is due to a process called beam hardening. In this work the beam hardening of microtomography images of vertebrae of Wistar rats subjected to a study of hyperthyroidism was corrected by the method of linearization of the projections. It was discretized using a spectrum in energy, also called the spectrum of Herman. The results without correction for beam hardening showed significant differences in bone volume, which could lead to a possible diagnosis of osteoporosis. But the data with correction showed a decrease in bone volume, but this decrease was not significant in a confidence interval of 95%. (author)
Directory of Open Access Journals (Sweden)
Leonid KROUPNIK
Full Text Available In underground mining of solid minerals becoming increasingly common development system with stowing hardening mixtures. In this case the natural ore array after it is replaced by an artificial excavation of solidified filling mixture consisting of binder, aggregates and water. Such a mixture is prepared on the surface on special stowing complexes and transported underground at special stowing pipelines. However, it is transported to the horizons of a few kilometers, which requires a sustainable mode of motion of such a mixture in the pipeline. Hardening stowing mixture changes its rheological characteristics over time, which complicates the calculation of the parameters of pipeline transportation. The article suggests a method of determining the initial parameters of such mixtures: the status coefficient, indicator of transportability, coefficient of hydrodynamic resistance to motion of the mixture. These indicators characterize the mixture in terms of the possibility to transport it through pipes. On the basis of these indicators is proposed methodology for calculating the parameters of pipeline transport hardening filling mixtures in drift mode when traffic on the horizontal part of the mixture under pressure column of the mixture in the vertical part of the backfill of the pipeline. This technique allows stable operation is guaranteed to provide pipeline transportation.
Directory of Open Access Journals (Sweden)
Full Text Available Nowadays, large amounts of waste materials are being produced in the world. One of the waste materials is plastic bottle. Generating disposable plastic bottles is becoming a major problem in many countries. Using waste plastic as a secondary material in construction projects would be a solution to overcome the crisis of producing large amount of waste plastics in one hand and improving the structure's characteristics such as resistance against cracking on the other hand. This study aimed to investigate the effects of adding plastic bottles in road pavement. Marshall properties as well as specific gravity of asphalt mixture containing different percentages of plastic bottles were evaluated. Besides, Optimum Asphalt Content (OAC was calculated for each percentages of plastic bottles used in the mix. The stiffness and fatigue characteristics of mixture were assessed at OAC value. Results showed that the stability and flow values of asphalt mixture increased by adding waste crushed plastic bottle into the asphalt mixture. Further, it was shown that the bulk specific gravity and stiffness of mixtures increased by adding lower amount of plastic bottles; however, adding higher amounts of plastic resulted in lower specific gravity and mix stiffness. In addition, it was concluded that the mixtures containing waste plastic bottles have lower OAC values compared to the conventional mixture, and this may reduce the amount of asphalt binder can be used in road construction projects. Besides, the mixtures containing waste plastic showed significantly greater fatigue resistance than the conventional mixture.
Recovery and reuse of asphalt roofing waste. Final report
Energy Technology Data Exchange (ETDEWEB)
Desai, S.; Graziano, G.; Shepherd, P.
Burning of asphalt roofing waste as a fuel and incorporating asphalt roofing waste in bituminous paving were identified as the two outstanding resource recovery concepts out of ten studied. Four additional concepts might be worth considering under different market or technical circumstances. Another four concepts were rated as worth no further consideration at this time. This study of the recovery of the resource represented in asphalt roofing waste has identified the sources and quantities of roofing waste. About six million cubic yards of scrap roofing are generated annually in the United States, about 94% from removal of old roofing at the job site and the remainder from roofing material production at factories. Waste disposal is a growing problem for manufacturers and contractors. Nearly all roofing waste is hauled to landfills at a considerable expense to roofing contractors and manufacturers. Recovery of the roofing waste resource should require only a modest economic incentive. The asphalt contained in roofing waste represents an energy resource of more than 7 x 10/sup 13/ Btu/year. Another 1 x 10/sup 13/ Btu/year may be contained in field-applied asphalt on commercial building roofs. The two concepts recommended by this study appear to offer the broadest applicability, the most favorable economics, and the highest potential for near-term implementation to reuse this resource.
Aging test results of an asphalt membrane liner
International Nuclear Information System (INIS)
The objective of the asphalt aging study described in this report was to determine the expected performance lifetime of a catalytically airblown asphalt membrane as a seepage barrier for inactive uranium mill tailings. The study, conducted by Pacific Northwest Laboratory for the Department of Energy's Uranium Mill Tailings Remedial Action Program, showed through chemical compatibility tests that the asphalt membrane is well suited for this purpose. The chemical compatibility tests were designed to accelerate the aging reactions in the asphalt and to determine the accelerated aging effect. Higher temperatures and oxygen concentrations proved to be effective acceleration parameters. By infrared spectral analysis, the asphalt was determined to have undergone 7 years of equivalent aging in a 3-month period when exposed to 400C and 1.7 atm oxygen pressure. However, the extent of aging was limited to a maximum penetration of 0.5% of the total liner thickness. It was concluded that the liner could be expected to be effective as a seepage barrier for at least 1000 years before the entire thickness of the liner would be degraded
Hanford Protective Barriers Program asphalt barrier studies -- FY 1988
International Nuclear Information System (INIS)
The Hanford Protective Barrier (HPB) Program is evaluating alternative barriers to provide a means of meeting stringent water infiltration requirements. One type of alternative barrier being considered is an asphalt-based layer, 1.3 to 15 cm thick, which has been shown to be very effective as a barrier for radon gas and, hence, should be equally effective as a barrier for the larger molecules of water. Fiscal Year 1988 studies focused on the selection and formulation of the most promising asphalt materials for further testing in small-tube lysimeters. Results of laboratory-scale formulation and hydraulic conductivity tests led to the selection of a rubberized asphalt material and an admixture of 24 wt% asphalt emulsion and concrete sand as the two barriers for lysimeter testing. Eight lysimeters, four each containing the two asphalt treatments, were installed in the Small Tube Lysimeter Facility on the Hanford Site. The lysimeter tests allow the performance of these barrier formulations to be evaluated under more natural environmental conditions
An Approach for Nonlinear Fatigue Damage Evaluation in Asphalt Pavements
Rajbongshi, Pabitra; Thongram, Sonika
Fatigue due to vehicular loads is one of the primary distress mechanisms in asphalt pavements. It happens primarily due to deterioration in asphalt material with load repetitions. Degradation of asphalt material may be evaluated using different parameters. In view of degradation, the incremental damage in a given pavement section would be different for different repetitions, even with same loadings. Therefore, the damage progression becomes nonlinear with repetitions. Accounting such nonlinearity in damage accumulation, and based on different damage evaluation parameters, this paper presents an equivalent approach for fatigue damage evaluation in asphalt pavements. Traditional fatigue equation adopted in mechanistic-empirical pavement design has been used in the present work. Four different criteria, namely number of load repetitions, asphalt stiffness reduction, strain enhancement and fatigue life reduction with repetitions are considered for damage estimation. The proposed approach could estimate same value of nonlinear damage, irrespective of the criteria used. The simplest form of criterion i.e. the number of load repetitions can be used for fatigue performance evaluation. Probabilistically, the damage propagation is also correlated and assessed with the failure probability.
Application of asphalt rubber technology to recreational trails
Ni, Haifeng
Crumb rubber aggregate was employed instead of stone/sand aggregate in asphalt pavement that was modified by fine rubber particles. Crumb rubber aggregate forms an elastic network in the asphalt, which improves the pavement's susceptibility to low-temperature cracking, and absorb more stress at the crack tips than the conventional asphalt pavement. Laboratory tests were conducted to evaluate the tension/compression performance of a blend of asphalt rubber with rubber aggregate (ARRA). An optimum design methodology was introduced by examining the effect of asphalt source, curing temperature, curing time, rubber content, aggregate size, compaction pressure, and the effect of certain additives. At ambient temperature, the ARRA with equal amount of binder and aggregate exhibits good mechanical properties. Vestenamer helps improve the pavement's strength, stiffness, and fracture resistance to low temperature cracking. It was demonstrated that such pavement meets the mechanical requirements for recreational trails, such as bicycle, or pedestrian trails. ARRA is a viscoelastic material which exhibits time-dependent and loading rate-dependent behavior. Temperature is a key issue to its response to an external load. Both temperature and rate dependences were investigated. A series of uniaxial compression relaxation tests on ARRA or Vestenamer modified ARRA were conducted at room temperature to study the time-dependent performance of ARRA. Schapery's theory was applied to characterize the nonlinear viscoelastic behavior of ARRA.
European experience with asphalt packaging of radioactive wastes
International Nuclear Information System (INIS)
In Europe, the use of asphalt is synonymous with volume reduction of low and medium level radioactive waste. It started at Marcoule, France in the early 1960's and soon was adopted by Karlsruhe in West Germany, Eurochemic in Belgium, and in other countries. The use of an asphalt (or bitumen) binder, or immobilizing agent, in the VRS (Volume Reduction and Solidification) process proved to be beneficial in many ways. At Karlsruhe, for example, the VRS asphalt system replaced a cement system (non-volume reducing) and resulted in two drums of solidified waste versus ten with cement. This process reduced the transportation problem considerably. Asphalt is an inert, waterproof material and provides significantly improved package integrity under all conditions of on-site storage, transportation, and burial. The asphalt VRS system provides considerable cost savings, particularly for the recurring items such as binder, containers, transportation, and burial. These annual savings may approach $500,000 annually for a 1000 MWe nuclear plant. End product advantages include higher resistance to leaching and other environmental impacts, as well as less internal corrosion of the drums
Determination of Rheological Properties of Bio Mastic Asphalt
Directory of Open Access Journals (Sweden)
R. Muniandy
Full Text Available Due to the high oil prices the price of asphalt binder has increased tremendously. This scenario has warranted demand for higher viscosity cheaper asphalt for pavement construction. A study was conducted to take advantage of the Empty Fruit Bunch (EFB of Date and Oil Palm trees (which are considered as waste to produce cellulose fiber to be used as additives in the asphalt binder. If these EFB's could be beneficially utilized in any application, it would reduce the load on the nation's landfills and at the same time reducing the cost of road construction. A total of 11 blends were prepared that consisted of 5 blends with date palm fiber, 5 blends with oil palm fiber and one control sample that contained no fibers. The samples were evaluated using Dynamic Shear Rheometer (DSR equipment in accordance with the superpave Strategic Highway Research Program (SHRP requirements. The neat asphalt binders (Unaged, Rolling Thin Film Oven (RTFO aged and Pressure Ageing Vessel (PAV samples were then measured for phase angle, shear strain and complex shear modulus and then evaluated in accordance with SHRP requirements. The results indicated that the fibers enhanced the rheological performance of Bio Mastic Asphalt (BMA blends. The control sample which was categorized as PG58 was enhanced to PG76 with 0.375% date palm fiber. The oil palm has also improved the blend up to PG70 with 0.3% oil palm fiber.
Tetrapyrroles and associated compounds in Dead Sea asphalts
Energy Technology Data Exchange (ETDEWEB)
Aizenshtat, Z. (Hebrew Univ. of Jerusalem, Israel); Dinur, D.; Nissenbaum, A.
Metallo- and free porphyrins (1000 to 1500 ppM) isolated from asphalts occurring as huge blocks floating in the northern part of the Dead Sea, have been analyzed by visible-uv (v-uv) spectrophotometry and by mass spectrometry. The concentration of vanadyl porphyrins in the asphalts exceeds by far that of the Ni-porphyrins, despite the l:3 V/Ni ratio found in the total asphalt sample. The free porphyrins resemble those from the Uinta Basin (USA) gilsonite and contain a mixture of homologous Aetio- and deoxyphyllo-erythroaetioporphyrins (DPEP). The non-porphyrin fraction of the asphalt showed an identical aliphatic, hydrocarbon distribution with that of heavy crude oil from the same area. The more polar fraction associated with the porphyrins was compared with the polar fraction of the previously described ozokerite from the Dead Sea area. From high-resolution MS, IR, v-uv and NMR spectra, combined with hydrolysis and GLC analysis, it is suggested that even-numbered (C/sub 12/, C/sub 16/, C/sub 18/, C/sub 18/ /sub 1/, C/sub 22/) fatty acids are associated with the asphaltic porphyrins, probably in the triglyceride form.
Performance evaluation of high modulus asphalt concrete mixes
Haritonovs, V.; Tihonovs, J.; Zaumanis, M.
Dolomite is one of the most available sedimentary rocks in the territory of Latvia. Dolomite quarries contain about 1000 million tons of this material. However, according to Latvian Road Specifications, this dolomite cannot be used for average and high intensity roads because of its low quality (mainly, LA index). Therefore, mostly imported magmatic rocks (granite, diabase, gabbro, basalt) or imported dolomite are used which makes asphalt expensive. However, practical experience shows that even with these high quality materials roads exhibit rutting, fatigue and thermal cracks. The aim of the research is to develop a high performance asphalt concrete for base and binder courses using only locally available aggregates. In order to achieve resistance against deformations at a high ambient temperature, a hard grade binder was used. Workability, fatigue and thermal cracking resistance, as well as sufficient water resistance is achieved by low porosity (3-5%) and higher binder content compared to traditional asphalt mixtures. The design of the asphalt includes a combination of empirical and performance based tests, which in laboratory circumstances allow simulating traffic and environmental loads. High performance AC 16 base asphalt concrete was created using local dolomite aggregate with polymer modified (PMB 10/40-65) and hard grade (B20/30) bitumen. The mixtures were specified based on fundamental properties in accordance to EN 13108-1 standard.
Deformation behaviour of dispersion hardened nanocrystalline copper
Directory of Open Access Journals (Sweden)
J.P. Stobrawa
Full Text Available Purpose: The aim of this work was to describe deformation behaviour of nanocrystalline copper dispersion-hardened with nanoparticles of tungsten carbide and yttria.Design/methodology/approach: Tests were made with the Cu, Cu-WC and Cu-Y2O3 micro-composites containing up to 3 % of a hardening phase. These were obtained by powder metallurgy techniques, i.e. milling the input powders in the planetary ball mills, compacting and sintering. The mechanical properties (hardness, 0,2 YS, elongation during compression test and microstructure were examined by the optical, scanning and transmission electron microscopy.Findings: Analysis of the initial nanocrystalline structure of these materials was made, and its evolution during deformation process was investigated with an account of the hardening effect and the changes in the mechanical and plastic properties. Results of this analysis have been discussed based on the existing theories related to hardening of nanocrystalline materials.Research limitations/implications: The powder metallurgy techniques make it possible to obtain copper-based bulk materials by means of milling input powders in the planetary ball, followed by compacting and sintering. Additional operations of hot extrusion are also often used. There is some threat, however, that during high-temperature processing or using these materials at elevated or high temperatures this nanometric structure may become unstable. The studies have shown the importance of "flows" in the consolidated materials such as pores or regions of poor powder particles joining which significantly deteriorate mechanical properties of compacted and sintered powder micro composites.Practical implications: A growing trend to use new copper-based functional materials is observed recently world-wide. Within this group of materials particular attention is drawn to those with nanometric grain size of a copper matrix, which exhibit higher mechanical properties than
Directory of Open Access Journals (Sweden)
Nikolaev N. N.
Full Text Available The article explains the importance of the transport process when performing repair jobs of asphalt roads. The scheme of the technological process was drawn up; job steps were identified, while the latter may be characterized by non-productive downtime of transport as well as that one of technological machines. We have analyzed the following steps of the flowchart of the road concrete mix transportation: the preparation of the road concrete mix for transportation, loading, transportation, unloading, laying and packing. The transportation of goods starts at the working site of their production and ends at the site of their consumption. The transportation process is a multistep and multioperational process having the greater diversity of technological, operational and economic operations, which must be correctly organized. It is extremely important to deliver the road concrete mix of coating plant (OP just in time, while avoiding the unproductive idle standing of the equipment, the deterioration of the mixture, as well as performing the job steps at minimum transportation cost savings. The successful combining of the steps of the concept organization of the road concrete mix transportation (coating plant, asphalt laying step, transportation step will improve the performance and will provide the reduction of the job cost. One must perform the coordination of job steps on different road sections using information technologies and communication facility
Production of De-asphalted Oil and Fine Asphalt Particles by Supercritical Extraction
Institute of Scientific and Technical Information of China (English)
赵锁奇; 许志明; 王仁安
A continuous three-stage supercritical fluid extraction (SFE) process with a capacity of 1.0kg.h-1 was setup to extract petroleum residue by pentane to obtain more oil for further upgrading. A discharging system integrated to the bottom of the extractor was used to recover solvent as gas while asphalt was obtained as fine particles. The influence of operating conditions on the yield and quality of extracts, i.e., deasphalted oil (DAO) and resin, was studied in the range of temperature 150-220℃, pressure of 4.0-6.0 MPa and the mass ratio of solvent to oil feed (S/O) 2.5-5.0. The particle size distribution, apparent forms and the packing density, which vary with operating pressure, were measured. The particle structures were observed by SEM as well. With the modification to conventional processes, furnace can be eliminated for solvent recovery from asphalt phase, so as to reduce energy consumption.
A pulsed-and high resolution-NMR study of the asphalt compositions obtained by the composition analytical method
International Nuclear Information System (INIS)
12 Kinds of asphalts were fractionated by the usual composition analytical method to give asphaltenes, maltenes, and waxy substances. Their contents show fairly good relationships with softening temperatures, and 1/T2 values of asphalts. Pulsed- and high resolution-NMR measurements were made of the fractions of 8 asphalts out of 12 asphalts. Asphaltenes from all the asphalts were thought to have almost same structures and characters (T2 asymptotically equals μsec), and their contents vary with the asphalts. Maltenes had no characteristic structures owing to the imperfect fractionation employed in this study, and their content in the asphalt is the largest. (author)
Empirical beam hardening correction (EBHC) for CT
Energy Technology Data Exchange (ETDEWEB)
Kyriakou, Yiannis; Meyer, Esther; Prell, Daniel; Kachelriess, Marc [Institute of Medical Physics, University of Erlangen-Nuernberg, 91052 Erlangen (Germany)
Purpose: Due to x-ray beam polychromaticity and scattered radiation, attenuation measurements tend to be underestimated. Cupping and beam hardening artifacts become apparent in the reconstructed CT images. If only one material such as water, for example, is present, these artifacts can be reduced by precorrecting the rawdata. Higher order beam hardening artifacts, as they result when a mixture of materials such as water and bone, or water and bone and iodine is present, require an iterative beam hardening correction where the image is segmented into different materials and those are forward projected to obtain new rawdata. Typically, the forward projection must correctly model the beam polychromaticity and account for all physical effects, including the energy dependence of the assumed materials in the patient, the detector response, and others. We propose a new algorithm that does not require any knowledge about spectra or attenuation coefficients and that does not need to be calibrated. The proposed method corrects beam hardening in single energy CT data. Methods: The only a priori knowledge entering EBHC is the segmentation of the object into different materials. Materials other than water are segmented from the original image, e.g., by using simple thresholding. Then, a (monochromatic) forward projection of these other materials is performed. The measured rawdata and the forward projected material-specific rawdata are monomially combined (e.g., multiplied or squared) and reconstructed to yield a set of correction volumes. These are then linearly combined and added to the original volume. The combination weights are determined to maximize the flatness of the new and corrected volume. EBHC is evaluated using data acquired with a modern cone-beam dual-source spiral CT scanner (Somatom Definition Flash, Siemens Healthcare, Forchheim, Germany), with a modern dual-source micro-CT scanner (TomoScope Synergy Twin, CT Imaging GmbH, Erlangen, Germany), and with a modern
The effect of aggregate density on pavement performance of SMA-13 asphalt mixture
Directory of Open Access Journals (Sweden)
Qiao Yinping
Full Text Available This paper chooses the top layer SMA-13 asphalt mixture material as the research object. Basalt was selected as pavement material, and modified SBS asphalt was used as a cementing material. Two basalt aggregates with different densities were used to carry out standard Marshall test in the laboratory.Aimed at the volume parameters of the asphalt mixture carry on anaiysis,and obtian the effect of aggregate density on pavement performance of SMA-13 asphalt mixture, which is that the density of aggregate has a significant effect on the void ratio, saturation, and the gap rate of the aggregate, thus affecting the pavement performance of the asphalt mixture
Hanford Permanent Isolation Barrier Program: Asphalt technology test plan
Energy Technology Data Exchange (ETDEWEB)
Freeman, H.D.; Romine, R.A.
The Hanford Permanent Isolation Barriers use engineered layers of natural materials to create an integrated structure with backup protective features. The objective of current designs is to develop a maintenance-free permanent barrier that isolates wastes for a minimum of 1000 years by limiting water drainage to near-zero amounts. Asphalt is being used as an impermeable water diversion layer to provide a redundant layer within the overall barrier design. Data on asphalt barrier properties in a buried environment are not available for the required 100-year time frame. The purpose of this test plan is to outline the activities planned to obtain data with which to estimate performance of the asphalt layers.
Asphalt emulsion sealing of uranium mill tailings. 1980 annual report
International Nuclear Information System (INIS)
Studies of asphalt emulsion sealants conducted by the Pacific Northwest Laboratory have demonstrated that the sealants are effective in containing radon and other potentially hazardous material within uranium tailings. The laboratory and field studies have further demonstrated that radon exhalation from uranium tailings piles can be reduced by greater than 99% to near background levels. Field tests at the tailings pile in Grand Junction, Colorado, confirmed that an 8-cm admix seal containing 22 wt% asphalt could be effectively applied with a cold-mix paver. Other techniques were successfully tested, including a soil stabilizer and a hot, rubberized asphalt seal that was applied with a distributor truck. After the seals were applied and compacted, overburden was applied over the seal to protect the seal from ultraviolet degradation
Deformation Parameters and Fatigue of the Recycled Asphalt Mixtures
Directory of Open Access Journals (Sweden)
Šrámek Juraj
Full Text Available The deformational properties of asphalt mixtures measured by dynamic methods and fatigue allow a design the road to suit the expected traffic load. Quality of mixtures is also expressed by the resistance to permanent deformation. Complex modulus of stiffness and fatigue can reliably characterize the proposed mixture of asphalt pavement. The complex modulus (E* measurement of asphalt mixtures are carried out in laboratory of Department of Construction Management at University of Žilina by two-point bending test method on trapezoid-shaped samples. Today, the fatigue is verified on trapezoid-shaped samples and is assessed by proportional strain at 1 million cycles (ε6. The test equipment and software is used to evaluate fatigue and deformation characteristics.
Nuclear asphalt content gauge study. Research report (Final)
International Nuclear Information System (INIS)
This research ascertains if the Troxler Model 3241 Gauge could accurately determine the asphalt content of bituminous-concrete mixtures by nuclear means. The study was divided into three phases. Phase I was conducted in the Central Laboratory where a series of controlled tests were performed for variables that may effect the gauge's asphalt-content determinations. Phase II evolved into a cooperative study between the Maryland State Highway Administration (SHA) and several bituminous concrete producers. Phase III was to report the findings of the study and make a recommendation on the overall practical application of the gauge. The results indicate that the gauge can accurately determine asphalt contents on normal surface and base bituminous mixtures
Application of asphalt emulsion seals to uranium mill tailings
International Nuclear Information System (INIS)
Studies of asphalt emulsion sealants have demonstrated that the sealants are effective in containing radon and other potentially hazardous material within uranium tailings. The laboratory and field studies have further demonstrated that radon exhalation from uranium tailings piles can be reduced by greater than 99% to less than background levels. Field tests at the tailings pile in Grand Junction, Colorado confirmed that an 8-cm admix seal containing 22 wt % asphalt could be effectively applied with a cold-mix paver. Other techniques were successfully tested, including a soil stabilizer and a hot, rubberized asphalt seal that was applied with a distributor truck. After the seals were applied and conpacted, overburden was applied over the seal to protect the seal from ultraviolet degradation. 14 figures
Investigation of Asphalt Mixture Creep Behavior Using Thin Beam Specimens
International Nuclear Information System (INIS)
The asphalt pavement layer consists of two or more lifts of compacted asphalt mixture; the top of the layer is also exposed to aging, a factor that significantly affects the mixture properties. The current testing specifications use rather thick specimens that cannot be used to investigate the gradual change in properties with pavement depth. This paper investigates the feasibility of using the 3-point bending test with thin asphalt mixture beams (127x12.7x6.35 mm) to determine the low-temperature creep compliance of the mixtures. Several theoretical and semi-empirical models, from the theory of composites, are reviewed and evaluated using numerical and experimental data. Preliminary results show that this method can be used for low-temperature mixture characterization but several crucial factors need further inspection and interpretation
Hanford Permanent Isolation Barrier Program: Asphalt technology test plan
International Nuclear Information System (INIS)
The Hanford Permanent Isolation Barriers use engineered layers of natural materials to create an integrated structure with backup protective features. The objective of current designs is to develop a maintenance-free permanent barrier that isolates wastes for a minimum of 1000 years by limiting water drainage to near-zero amounts. Asphalt is being used as an impermeable water diversion layer to provide a redundant layer within the overall barrier design. Data on asphalt barrier properties in a buried environment are not available for the required 100-year time frame. The purpose of this test plan is to outline the activities planned to obtain data with which to estimate performance of the asphalt layers
Asphalt emulsion sealing of uranium mill tailings. 1980 annual report
Energy Technology Data Exchange (ETDEWEB)
Hartley, J.N.; Koehmstedt, P.L; Esterl, D.J.; Freeman, H.D.; Buelt, J.L.; Nelson, D.A.; Elmore, M.R.
Studies of asphalt emulsion sealants conducted by the Pacific Northwest Laboratory have demonstrated that the sealants are effective in containing radon and other potentially hazardous material within uranium tailings. The laboratory and field studies have further demonstrated that radon exhalation from uranium tailings piles can be reduced by greater than 99% to near background levels. Field tests at the tailings pile in Grand Junction, Colorado, confirmed that an 8-cm admix seal containing 22 wt% asphalt could be effectively applied with a cold-mix paver. Other techniques were successfully tested, including a soil stabilizer and a hot, rubberized asphalt seal that was applied with a distributor truck. After the seals were applied and compacted, overburden was applied over the seal to protect the seal from ultraviolet degradation.
Deformation Parameters and Fatigue of the Recycled Asphalt Mixtures
Šrámek, Juraj
The deformational properties of asphalt mixtures measured by dynamic methods and fatigue allow a design the road to suit the expected traffic load. Quality of mixtures is also expressed by the resistance to permanent deformation. Complex modulus of stiffness and fatigue can reliably characterize the proposed mixture of asphalt pavement. The complex modulus (E*) measurement of asphalt mixtures are carried out in laboratory of Department of Construction Management at University of Žilina by two-point bending test method on trapezoid-shaped samples. Today, the fatigue is verified on trapezoid-shaped samples and is assessed by proportional strain at 1 million cycles (ɛ6). The test equipment and software is used to evaluate fatigue and deformation characteristics.
Modelling and Laboratory Studies on the Adhesion Fatigue Performance for Thin-Film Asphalt and Aggregate System
Dongsheng Wang; Junyan Yi; Decheng Feng
Adhesion between asphalt and aggregate plays an important role in the performance of asphalt mixtures. A low-frequency adhesion fatigue test was proposed in this paper to study the effect of environment on the asphalt-aggregate adhesion system. The stress-based fatigue model had been utilized to describe the fatigue behavior of thin-film asphalt and aggregate system. The factors influencing the adhesion fatigue performance were also investigated. Experiment results show that asphalt has more ...
Final environmental and regulatory assessment of using asphalt as a sealant in mine shafts
International Nuclear Information System (INIS)
This report discusses the properties of asphalt, the current regulatory status governing asphalt and future regulatory implications which may be pertinent in using asphalt as a waterproof shaft sealant. An understanding of the inherent organic composition of asphalt, an increase in the number of health and environmental research publications conducted on asphalt and an examination of the apparent trend of regulatory agencies toward more stringent environmental regulation governing the use of organic materials suggests asphalt could become regulated at a future time. This would only occur, however, if asphalt was found to conform to the present regulatory definitions of pollutants, contaminants or hazardous substances or if asphalt was included on a regulated substance list. In this regard, the study points out that asphalt contains very low levels of hazardous poly-nuclear aromatics (PNA's). These levels are significantly lower than the levels present in coal tars, a substance known to contain high levels of hazardous PNA's. Asphalt, however, has the inherent potential of producing higher concentrations of PNA's if the adverse condition of cracking should occur during the refinery production stage or on-site preparation of the asphalt. Also, unless existing control technology is applied, emission levels of sulfur dioxide, carbon monoxide, particulates and volatile organic carbons from the on-site preparation facilities could approach the permissible health standard levels of EPA. The study indicates, however, that available literature is limited on these issues
An investigation of waste foundry sand in asphalt concrete mixtures.
Bakis, Recep; Koyuncu, Hakan; Demirbas, Ayhan
A laboratory study regarding the reuse of waste foundry sand in asphalt concrete production by replacing a certain portion of aggregate with WFS was undertaken. The results showed that replacement of 10% aggregates with waste foundry sand was found to be the most suitable for asphalt concrete mixtures. Furthermore, the chemical and physical properties of waste foundry sand were analysed in the laboratory to determine the potential effect on the environment. The results indicated that the investigated waste foundry sand did not significantly affect the environment around the deposition PMID:16784170
Asphaltic concrete overlays of rigid and flexible pavements
Kinchen, R. W.; Temple, W. H.
The development of a mechanistic approach to overlay thickness selection is described. The procedure utilizes a deflection analysis to determine pavement rehabilitation needs. Design guides for selecting the overlay thickness are presented. Tolerable deflection-traffic load relationships and the deflection attenuation properties of asphaltic concrete were developed, representing the subgrade support conditions and properties of materials used in Louisiana. All deflection measurements on asphaltic concrete were corrected for the effect of temperature. Deflection measurements taken before and after overlay were also adjusted to minimize the effects of seasonal subgrade moisture variation.
Reduction in radiation exposure and volume using asphalt solidification
International Nuclear Information System (INIS)
The solidification of liquid and solid radioactive wastes from nuclear power plants with an extruder-evaporator using an asphalt binder minimizes both volume and radiation exposure. The automatic evaporation of water in liquid radwastes prior to incorporation into asphalt reduces the volume to be transported and disposed. In turn, the numbers of drums requiring handling is reduced 5 to 10 times thereby lessening the chances for radiation exposure. Also, the extruder-evaporator is self-shielded and contains only about one gallon of the radwaste. Dose rates at the surface of the equipment and filled containers from commercially operating systems for the past 10 years in Europe are given
Directory of Open Access Journals (Sweden)
A. S. Surmak
Full Text Available It is proposed to evaluate quality of asphalt concrete mixture through definition of current component variable of a drive motor and measurement of its derivative sign. In order to carry out final determination of mixture uniformity a transducer on the basis of a nuclear magnetic resonance is applied. Block diagram of the system is presented and algorithm of its operation is given in the paper. In addition to improvement of the finished product quality the application of the system makes it possible to reduce bitumen consumption used for production of asphalt concrete.
Numerical simulation on the thermal response of heat-conducting asphalt pavements
International Nuclear Information System (INIS)
Using asphalt pavements as a solar collector is a subject of current interest all over the world because the sun provides a cheap and abundant source of clean and renewable energy, which can be captured by black asphalt pavements. A heat-conducting device is designed to absorb energy from the sun. In order to validate what parameters are critical in the asphalt collector, a finite element model is developed to predict the thermal response of the heat-conducting device compared to the conventional asphalt mixture. Some factors that may affect the asphalt pavement collector are considered, including the coefficient of heat conductivity of the asphalt pavement, the distance between pipes with the medium, water, and the pipe's diameter. Ultimately, the finite element model can provide pavement engineers with an efficient computational tool that can be a guide to the conductive asphalt solar collector's experiment in the laboratory.
Numerical simulation on the thermal response of heat-conducting asphalt pavements
Wang, Hong; Wu, Shaopeng; Chen, Mingyu; Zhang, Yuan
Using asphalt pavements as a solar collector is a subject of current interest all over the world because the sun provides a cheap and abundant source of clean and renewable energy, which can be captured by black asphalt pavements. A heat-conducting device is designed to absorb energy from the sun. In order to validate what parameters are critical in the asphalt collector, a finite element model is developed to predict the thermal response of the heat-conducting device compared to the conventional asphalt mixture. Some factors that may affect the asphalt pavement collector are considered, including the coefficient of heat conductivity of the asphalt pavement, the distance between pipes with the medium, water, and the pipe's diameter. Ultimately, the finite element model can provide pavement engineers with an efficient computational tool that can be a guide to the conductive asphalt solar collector's experiment in the laboratory.
Criteria for asphalt-rubber concrete in civil airport pavements: Mixture design
Roberts, F. L.; Lytton, R. L.; Hoyt, D.
A mixture design procedure is developed to allow the use of asphalt-rubber binders in concrete for flexible airport pavement. The asphalt-rubber is produced by reacting asphalt with ground, scrap tire rubber to produce the binder for the asphalt-rubber concrete. Procedures for laboratory preparation of alsphalt-rubber binders using an equipment setup that was found by researchers to produce laboratory binders with similar properties to field processes are included. The rubber-asphalt concrete mixture design procedure includes adjustments to the aggregate gradation to permit space for the rubber particles in the asphalt-rubber binder as well as suggested mixing and compaction temperatures, and compaction efforts. While the procedure was used in the laboratory to successfully produce asphalt-rubber concrete mixtures, it should be evaluated in the field to ensure that consistent results can be achieved in a production environment.
Influence of limestone fillers on combustion characteristics of asphalt mortar for pavements
DEFF Research Database (Denmark)
Ke, Wu; Kai, Zhu; Wu, Hao;
Asphalt materials will be ignited and release significant toxic fumes within tunnel fires. Thus, combustion characteristics of asphalt materials used in road tunnel should be studied in order to limit such an adverse effect. In the present work we study the influence of limestone fillers on combu......Asphalt materials will be ignited and release significant toxic fumes within tunnel fires. Thus, combustion characteristics of asphalt materials used in road tunnel should be studied in order to limit such an adverse effect. In the present work we study the influence of limestone fillers...... on combustion characteristics of asphalt mortar by thermogravimetric and kinetic analysis. It is shown that the combustion of asphalt mortar is not just a linear superposition of asphalt and limestone. The limestone will increase the ignition point and the activation energy of the primary volatile release...... the assumption of random nucleation and nuclei growth, whereas the limestone decomposition stage appears to follow the one-dimensional phase boundary model....
Influence Of The Powder/Asphalt Ratio On The High Stress Responses Of Crumb Rubber Modified Asphalt Mortars
Directory of Open Access Journals (Sweden)
Ma Tengfei
Full Text Available In order to study different powder/asphalt ratios effect on nonlinear viscoelastic responses of mortar, this paper choose limestone as the filler, and powder/asphalt ratio is 0.2,0.4,0.6,and 0.8.The tests were conducted using a Dynamic Shear Rheometer to perform multiple stress creep recovery (MSCR tests.The test results show that,with the increase of powder/asphalt ratio irrecoverable creep compliance(Jnr value of the mortar , decrease gradually, and the amplitude is larger.High temperature performance of the mortar are improve obviously.Using environmental scanning electron microscopy to scan those mortars,it analyzed the improvement of mortar from the microcosmic mechanism.
Background of superpave asphalt mixture design and analysis. National asphalt training center demonstration project 101. Final report, December 1992-November 1994
Energy Technology Data Exchange (ETDEWEB)
McGennis, R.B.; Anderson, R.M.; Kennedy, T.W.; Solaimanian, M.
The manual represents the first formal training document that embodies the complete series of SUPERPAVE asphalt mixture design and analysis test equipment and procedures. These tests and procedures represent the results of the SHRP 5-year research effort to investigate and improve asphalt cement technology. This manual was developed under the FHWA`s National Asphalt Training Center. Students attending the center utilize this manual to obtain a better understanding of the underlying theory behind asphalt mixture design and analysis, as well as how to perform each of the new procedures.
Effect of Overaging on Solute Distributions and Bake Hardening Phenomenon in Bake Hardening Steels%Effect of Overaging on Solute Distributions and Bake Hardening Phenomenon in Bake Hardening Steels
Institute of Scientific and Technical Information of China (English)
WANG Hua; SHI Wen; HE Yan-lin; LU Xiao-gang; LI Lin
Specimens of two different kinds of bake hardening steels (BH-Mn and BH-P) were prepared and treated with different annealing processes (water quenching and overaging). A novel technique of three dimensional atom probe was used to investigate solute distributions in these steels. The results indicate that C concentration decreases, whereas V increases during overaging in both bake hardening steels. The conclusion that no vanadium carbides pre- cipitate during the overaging is therefore originally obtained by microanalysis in bake hardening steels. Moreover, bake hardening values of all the specimens were tested by tensile experiments with 2 0/~ pre-deformation. However, those of overaged specimens were further measured with higher levels of pre-deformation because no bake hardening phenomenon was present at 2% pre-deformation. As the pre-deformation increases from 2% to 6% and 8%, both overaged steels show bake hardening values, and the value data are almost the same.
Analysis of Adhesive Characteristics of Asphalt Based on Atomic Force Microscopy and Molecular Dynamics Simulation.
Xu, Meng; Yi, Junyan; Feng, Decheng; Huang, Yudong; Wang, Dongsheng
Asphalt binder is a very important building material in infrastructure construction; it is commonly mixed with mineral aggregate and used to produce asphalt concrete. Owing to the large differences in physical and chemical properties between asphalt and aggregate, adhesive bonds play an important role in determining the performance of asphalt concrete. Although many types of adhesive bonding mechanisms have been proposed to explain the interaction forces between asphalt binder and mineral aggregate, few have been confirmed and characterized. In comparison with chemical interactions, physical adsorption has been considered to play a more important role in adhesive bonding between asphalt and mineral aggregate. In this study, the silicon tip of an atomic force microscope was used to represent silicate minerals in aggregate, and a nanoscale analysis of the characteristics of adhesive bonding between asphalt binder and the silicon tip was conducted via an atomic force microscopy (AFM) test and molecular dynamics (MD) simulations. The results of the measurements and simulations could help in better understanding of the bonding and debonding procedures in asphalt-aggregate mixtures during hot mixing and under traffic loading. MD simulations on a single molecule of a component of asphalt and monocrystalline silicon demonstrate that molecules with a higher atomic density and planar structure, such as three types of asphaltene molecules, can provide greater adhesive strength. However, regarding the real components of asphalt binder, both the MD simulations and AFM test indicate that the colloidal structural behavior of asphalt also has a large influence on the adhesion behavior between asphalt and silicon. A schematic model of the interaction between asphalt and silicon is presented, which can explain the effect of aging on the adhesion behavior of asphalt. PMID:27115043
Effects of asphalt rejuvenator on thermal and mechanical properties on oxidized hot mixed asphalt pavements
Farace, Nicholas A.; Buttlar, William G.; Reis, Henrique
The utilization of asphalt rejuvenator, and its effectiveness for restoring thermal and mechanical properties was investigated via Disk-shaped Compact Tension (DC(T)) and acoustic emission (AE) testing for determining mechanical properties and embrittlement temperatures of the mixtures. During the DC(T) testing the fracture energies and peak loads were used to measure the resistance of the rejuvenated asphalt to low temperature cracking. The AE testing monitored the acoustic emission activity while the specimens were cooled from room temperature to -40 °C to estimate the temperature at which thermal cracking began (i.e. the embrittlement temperature). First, a baseline response was obtained by obtaining the mechanical and thermal response of virgin HMA samples and HMA samples that had been exposed to oxidative aging for 36 hours at 135°C. The results showed the virgin samples had much higher peak loads and fracture energies than the 36 hours aged samples. Acoustic Emission showed similar results with the virgin samples having embrittlement temperatures 10 °C cooler than the 36 hours aged specimens. Then, overaged for 36 hours specimens were treated different amounts of rejuvenator (10%, 15%, and 20% by weight of binder content) and left to dwell for increased amount of time periods varying from one to eight weeks. It was observed that the AE results showed an improvement of embrittlement temperature with increasing with the dwell times. The 8 weeks specimens had cooler embrittlement temperatures than the virgin specimens. Finally, the low temperature effects on fracture energy and peak load of the rejuvenated asphalt was investigated. Rejuvenator was applied (10% by weight of binder) to specimens aged 36 hours at 135 °C, and the dwell time was varied from 1 to 4 weeks. The results showed that the peak loads were restored to levels of the virgin specimens, and the fracture energies improved to levels beyond that of the virgin specimens. The results also showed a
Progresses in irradiating SBS for road asphalt applications
International Nuclear Information System (INIS)
Technical developments at SINAP to improve properties of SBS, a styrene-butadiene- styrene copolymer, for road asphalt applications are reviewed. In an attempt to better solve problems related to undesirable compatibility of SBS to asphalt components, we proposed a new method to modify the SBS molecular chains with ionizing radiations through radiation graft copolymerization and radiation crosslinking. Grafting a monomer with polar functional groups onto SBS molecules improves compatibility of SBS to polar components of asphalt, hence enhanced storage stability of the polymer modified asphalt (PMA), while crosslinks of SBS molecular chains endues increased physical properties to the PMA. Mechanisms of the radiation effects were studied with a series of SBS samples irradiated by 60Co γ-rays or electron beams. The PMA and macadam-blended PMA samples showed higher performance than the control, i.e. SBS-modified asphalt by conventional approaches. The results can be summarized as follows. 1. The grafted SBS enhances thermostability of saturates and aromatics, the two asphalt components that exhibit the biggest SBS-swelling effect. The resins of asphalt, however, can hardly be absorbed by SBS, and the SBS is in a phase-separation status with the resins. Therefore, it is crucial to strengthen reactions between SBS and the resins to obtain stable and high quality PMA. 2. SBS molecular chains can be crosslinked with irradiation of a few tens of kGy. The crosslinking effect was evidenced by increased molecular weight of SBS and wider distribution of the molecular weight in GPC measurement of the irradiated SBS samples, and by decreased activation energy of viscosity in rheological measurement, in which the storage modulus G' increased and the loss modulus G' declined with increasing doses, indicating a larger elastic component and smaller viscous component in the irradiated SBS. Correspondingly, temperature sensitivity of the irradiated SBS reduced. Blended with SBS
Laser Surface Hardening of 9CrSi Steel
Institute of Scientific and Technical Information of China (English)
The effects of laser hardening parameters such as beam power, beam diameter and scanning rate on microstructureand hardness of 9CrSi steel were investigated. The microstructure of the surface layer of 9CrSi steel was changed frompearlite to martensite, retained austenite and carbide by laser hardening. The depth of the hardened layer increasedwith increasing laser energy density and the surface hardeness increased by 3~5 times as high as the untreated steel.The laser hardened surface had good wear resistance due to martensite and carbide in the surface layer. The wearmode at Iow speed was abrasive, while the wear mode at high speed was adhesive.
Configurable Radiation Hardened High Speed Isolated Interface ASIC Project
National Aeronautics and Space Administration — NVE Corporation will design and build an innovative, low cost, flexible, configurable, radiation hardened, galvanically isolated, interface ASIC chip set that will...
Modeling of asphalt and experiments with a discrete particles method
Ormel, T.J.; Magnanimo, V.; Huerne, ter H.L.; Luding, S.; Wilson, D.; Costello, S.; Henning, T.; Black, P.; Olsen, C.
Asphalt is an important road paving material. Besides an acceptable price, durability, surface conditions (like roughening and evenness), age-, weather- and traffic-induced failures and degradation are relevant aspects. In the professional road-engineering branch empirical models are used to describ
Performance related characterisation of the mechanical behaviour of asphalt mixtures
Molenaar, J.M.M.
The investigation was undertaken to support innovations in the field of asphalt pavement design and material selection, and to be able to evaluate or judge the risk of failure and cost-effectiveness of newly developed paving materials in order to justify their application. To be able to determine th
Sinopec Wins Bid for Special Asphalt for Racing Track
Institute of Scientific and Technical Information of China (English)
@@ On February 13 Sinopec and Shanghai International Circuit held a signing ceremony in Beijing for the contract to supply special asphalt for racing track use. Mr. Wang Jiming,Vice Board Chairman and President of Sinopec and Mr. Wang Tianpu, Senior Vice President of Sinopec, attended the ceremony.
Assessment of Water Quality of Runoff from Sealed Asphalt Surfaces
This report discusses the results of runoff tests from recently-sealed asphalt surfaces conducted at EPA's Urban Watershed Research Facility (UWRF) in Edison, New Jersey. Both bench-scale panels and full-scale test plots were evaluated. Full-scale tests were performed on an asp...
Asphalt and Wood Shingling. Roofing Workbook and Tests.
Brown, Arthur
This combination workbook and set of tests contains materials on asphalt and wood shingling that have been designed to be used by those studying to enter the roofing and waterproofing trade. It consists of seven instructional units and seven accompanying objective tests. Covered in the individual units are the following topics: shingling…
Characterization of Brazilian asphalt using X-ray diffraction
International Nuclear Information System (INIS)
Asphalt is a sticky, black and highly viscous liquid or semi-solid that is presented in most crude petroleum and in some natural deposits. The X ray diffraction can give valuable information over the characteristics of a material. Thus, the X-ray diffraction (XRD) method was employed to investigate parameters that characterize and differentiate asphalt groups (Boscan, CAP20, CAP40, CAP50/60, CAP50/70 and CAP85/100). The scattering measurements were carried out in θ-2θ reflection geometry using a powder diffractometer Shimadzu XRD-6000 at the Nuclear Instrumentation Laboratory, Brazil. Scans were typically done from 8 deg to 28 deg every 0.05. The parameters analyzed were: FWHM, peak area, peak center, peak height, left half width and right half width. Thus, in this study, scattering profiles from different asphalt groups were carefully measured in order to establish characteristic signatures of these materials. The results indicate that by using three parameters (peak centroid, peak area and peak intensity) it is possible to characterize and differentiate the asphalt. (author)
Improvement of the asphalt-waste products in leachability
International Nuclear Information System (INIS)
To improve in leachability of the asphalt products containing evaporator residue from BWR, a method of reducing the swelling of asphalt products, which is a major cause for increasing the leachability, has been developed. Leachability of the resultant asphalt products was examined by IAEA's method. The reduction of swelling is achieved successfully by addition of an equivalent quantity of calcium chloride to the sodium sulfate contained in the residue; the sodium sulfate is converted to calcium sulfate and sodium chloride. The specimen (Asphalt/Na2SO4: 0.5) prepared by this improved method shows little swelling when immersed in water. The specimen without addition of calcium chloride gives a cumulative leaching fraction of about 0.65 for 137Cs and 0.20 for 60Co in 30 days. On the contrary, the corresponding values in about 100 days of the specimen with calcium chloride added are 5 x 10-4 and 1 x 10-4 for 137Cs and 60Co, respectively. These results indicate that the method is promising for reducing the leachability. Coating of the specimen surface with a fresh bitumen further reduces the leachability to a negligibly small value. (author)
Mechanistic and Economical Characteristics of Asphalt Rubber Mixtures
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Mena I. Souliman
Full Text Available Load associated fatigue cracking is one of the major distress types occurring in flexible pavement systems. Flexural bending beam fatigue laboratory test has been used for several decades and is considered to be an integral part of the new superpave advanced characterization procedure. One of the most significant solutions to prolong the fatigue life for an asphaltic mixture is to utilize flexible materials as rubber. A laboratory testing program was performed on a conventional and Asphalt Rubber- (AR- gap-graded mixtures to investigate the impact of added rubber on the mechanical, mechanistic, and economical attributes of asphaltic mixtures. Strain controlled fatigue tests were conducted according to American Association of State Highway and Transportation Officials (AASHTO procedures. The results from the beam fatigue tests indicated that the AR-gap-graded mixtures would have much longer fatigue life compared with the reference (conventional mixtures. In addition, a mechanistic analysis using 3D-Move software coupled with a cost analysis study based on the fatigue performance on the two mixtures was performed. Overall, analysis showed that AR modified asphalt mixtures exhibited significantly lower cost of pavement per 1000 cycles of fatigue life per mile compared to conventional HMA mixture.
The adoption of innovative asphalt equipment in road construction
Habets, Thijs; Voordijk, Hans; Sijde, van der Peter
Purpose – The purpose of this paper is to provide insight into the adoption process of innovative asphalt equipment in road construction and how the level of knowledge as characterised by the level of education in the companies affects this process. The emphasis is on equipment used for transporting
The asphalt paving process: plans for action research
Miller, Seirgei; Huerne, ter Henny; Dorée, André; Atkin, Brian; Borgbrant, Jan
Recent significant changes in public sector procurement in the Netherlands are forcing road construction companies to professionalize one of their primary processes: on-site asphalt paving. This paper describes an initiative aimed at improving quality in the process. A literature review confirmed th
Design tool for the thermal energy potential of asphalt pavements
Loomans, M.G.L.C.; Oversloot, H.P.; Bondt, A. de; Jansen, R.; Rij, H. van
This paper describes the development of a design tool for the calculation of the thermal energy potential of a so-called asphalt collector. Two types of numerical models have been developed and validated against experimental results from a full-scale test-site. The validation showed to be a tedious
Performance of Recycled Asphalt Pavement as Coarse Aggregate in Concrete
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Fidelis O. OKAFOR
Full Text Available Recycled asphalt pavement (RAP is the reclaimed and reprocessed pavement material containing asphalt and aggregate. Most RAP is recycled back into pavements, and as a result there is a general lack of data pertaining to the mechanical properties for RAP in other possible applications such as Portland cement concrete. In the present study, some mechanical properties of Portland cement concrete containing RAP as coarse aggregate were investigated in the laboratory. Six concrete mixes of widely differing water/cement ratios and mix proportions were made using RAP as coarse aggregate. The properties tested include the physical properties of the RAP aggregate, the compressive and flexural strengths of the concrete. These properties were compared with those of similar concretes made with natural gravel aggregate. Results of the tests suggest that the strength of concrete made from RAP is dependent on the bond strength of the asphalt-mortar (asphalt binder-sand-filler matrix coatings on the aggregates and may not produce concrete with compressive strength above 25 MPa. However, for middle and low strength concrete, the material was found to compare favorably with natural gravel aggregate.
Using waste plastic bottles as additive for stone mastic asphalt
International Nuclear Information System (INIS)
Highlights: → The PET increased the stiffness level of the mixture improving its resistance level against permanent deformation. → The effects of waste PET on Marshall Stability, air void and bulk specific gravity of the mixture are significant. → The appropriate amount of PET was found to be 6% by weight of bitumen. -- Abstract: Currently, polymer modified asphalt mixture is a relatively costly mixture for paving roads. One way to reduce the cost of such constructions and rendering them more convenient is by using inexpensive polymers, i.e. waste polymers. The main purpose of this research is to determine the effect of incorporating waste plastic bottles (Polyethylene Terephthalate (PET)) on the engineering properties of stone mastic asphalt (SMA) mixture. The volumetric and mechanical properties of asphalt mixes that include various percentages of PET (0%, 2%, 4%, 6%, 8% and 10%) were calculated and assessed with laboratory tests. The appropriate amount of PET was found to be 6% by weight of bitumen. The outcomes were statistically analysed and the determination of the significance at certain confidence limits was performed with the two factor variance analysis (ANOVA). Moreover, some studies conducted on polyethylene modified asphalt mixture have also been taken into consideration in this paper. The results show that the addition of PET has a significant positive effect on the properties of SMA and it can promote the re-use of waste material in industry in an environmentally friendly and economical way.
Hardness variability in commercial and hardened technologies
International Nuclear Information System (INIS)
Over the past 10 years, there have been a number of advances in methods to assess and assure the radiation hardness of microelectronics in military and space applications. At the forefront of these is the Qualified Manufacturers List (QML) methodology, in which the hardness of product is ''built-in'' through statistical process control (SPC) of technology parameters relevant to the radiation response, test structure to integrated circuit (IC) correlations, and techniques for extrapolating laboratory test results to varying radiation scenarios. At the same time, there has been renewed interest in the use of commercial technology -- with its enhanced performance, reduced cost, and higher reliability -- in military and space systems. In this paper, we initially demonstrate the application of QML techniques to assure and control the radiation response of hardened technologies. Through several examples, we demonstrate intra-die, wafer-to-wafer, and lot-to-lot variations in a hardened technology. We observe 10 to 30% variations in key technology parameters that result from variability in geometry, process, and design layout. Radiation-induced degradation is seen to mirror preirradiation characteristics. We then evaluate commercial technologies and report considerably higher variability in radiation hardness, i.e., variations by a factor of two to five. This variability is shown to arise from a lack of control of technology parameters relevant to the radiation response, which a commercial manufacturer has no interest in controlling in a normal process flow
Hardened Client Platforms for Secure Internet Banking
Ronchi, C.; Zakhidov, S.
We review the security of e-banking platforms with particular attention to the exploitable attack vectors of three main attack categories: Man-in-the-Middle, Man-in-the-PC and Man-in-the-Browser. It will be shown that the most serious threats come from combination attacks capable of hacking any transaction without the need to control the authentication process. Using this approach, the security of any authentication system can be bypassed, including those using SecureID Tokens, OTP Tokens, Biometric Sensors and Smart Cards. We will describe and compare two recently proposed e-banking platforms, the ZTIC and the USPD, both of which are based on the use of dedicated client devices, but with diverging approaches with respect to the need of hardening the Web client application. It will be shown that the use of a Hardened Browser (or H-Browser) component is critical to force attackers to employ complex and expensive techniques and to reduce the strength and variety of social engineering attacks down to physiological fraud levels.
Hardness variability in commercial and hardened technologies
Energy Technology Data Exchange (ETDEWEB)
Shaneyfelt, M.R.; Winokur, P.S.; Meisenheimer, T.L.; Sexton, F.W.; Roeske, S.B.; Knoll, M.G.
Over the past 10 years, there have been a number of advances in methods to assess and assure the radiation hardness of microelectronics in military and space applications. At the forefront of these is the Qualified Manufacturers List (QML) methodology, in which the hardness of product is ``built-in`` through statistical process control (SPC) of technology parameters relevant to the radiation response, test structure to integrated circuit (IC) correlations, and techniques for extrapolating laboratory test results to varying radiation scenarios. At the same time, there has been renewed interest in the use of commercial technology -- with its enhanced performance, reduced cost, and higher reliability -- in military and space systems. In this paper, we initially demonstrate the application of QML techniques to assure and control the radiation response of hardened technologies. Through several examples, we demonstrate intra-die, wafer-to-wafer, and lot-to-lot variations in a hardened technology. We observe 10 to 30% variations in key technology parameters that result from variability in geometry, process, and design layout. Radiation-induced degradation is seen to mirror preirradiation characteristics. We then evaluate commercial technologies and report considerably higher variability in radiation hardness, i.e., variations by a factor of two to five. This variability is shown to arise from a lack of control of technology parameters relevant to the radiation response, which a commercial manufacturer has no interest in controlling in a normal process flow.
Some Properties of Emulsified Asphalt Paving Mixture at Iraqi Environmental Conditions
Directory of Open Access Journals (Sweden)
Shakir.A.Al-Mishhadani* Hasan.H.Al-Baid
Full Text Available Cold emulsified asphalt mixture is generally a mix made of emulsified asphalt withaggregate. Emulsified asphalt is manufactured from base asphalt, emulsifier agent and waterwith approximate percentage of 40% to 75% asphalt, 0.1% to 2.5% emulsifier and 25% to60% water plus some minor components. This study aims to use the cold emulsified asphaltmixtures for road construction and maintenance in Iraq as an alternative to the hot asphaltmixtures, due to its economical, practical and environmental advantages. This studyfocusedto test and evaluates the emulsified asphalt material properties to be used as paving mixture.The tested properties of emulsified asphalt mixture were bulk density, air voids, dry Marshallstability, wet Marshall stability, retained Marshall stability, flow tests and compared with thecommon used specification.The results indicate that the emulsified asphalt type cationic slowsetting low viscosity (CSS-1 is very suitable with quartz type of aggregate from Al-Nibaayquarry. From many trial mixes it is found that the best percentages of initial residual bitumencontent to produced adequateresults for coating test ,mixing ,compaction ,curing and Marshallstability were ranged from (2.5%, 3%,3.5%,4% and 4.5%, andthe optimum percentage is(3.5%.Finally it can be conducted that the emulsified asphalt mixture is a suitable alternativemixture to the hot asphalt mixture for road construction and maintenance in Iraq.
Some Properties of Emulsified Asphalt Paving Mixture at Iraqi Environmental Conditions
Directory of Open Access Journals (Sweden)
Full Text Available Cold emulsified asphalt mixture is generally a mix made of emulsified asphalt withaggregate. Emulsified asphalt is manufactured from base asphalt, emulsifier agent and waterwith approximate percentage of 40% to 75% asphalt, 0.1% to 2.5% emulsifier and 25% to60% water plus some minor components. This study aims to use the cold emulsified asphaltmixtures for road construction and maintenance in Iraq as an alternative to the hot asphaltmixtures, due to its economical, practical and environmental advantages. This studyfocusedto test and evaluates the emulsified asphalt material properties to be used as paving mixture.The tested properties of emulsified asphalt mixture were bulk density, air voids, dry Marshallstability, wet Marshall stability, retained Marshall stability, flow tests and compared with thecommon used specification.The results indicate that the emulsified asphalt type cationic slowsetting low viscosity (CSS-1 is very suitable with quartz type of aggregate from Al-Nibaayquarry. From many trial mixes it is found that the best percentages of initial residual bitumencontent to produced adequateresults for coating test ,mixing ,compaction ,curing and Marshallstability were ranged from (2.5%, 3%,3.5%,4% and 4.5%, andthe optimum percentage is(3.5%.Finally it can be conducted that the emulsified asphalt mixture is a suitable alternativemixture to the hot asphalt mixture for road construction and maintenance in Iraq.
Evaluation system for CO2 emission of hot asphalt mixture
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Bo Peng
Full Text Available The highway construction industry plays an important role in economic and development, but is also a primary source of carbon emission. Accordingly, with the global climate change, energy conservation and reduction of carbon emissions have become critical issues in the highway construction industry. However, to date, a model for the highway construction industry has not been established. Hence, to implement a low-carbon construction model for highways, this study divided asphalt pavement construction into aggregate stacking, aggregate supply, and other stages, and compiled a list of energy consumption investigation. An appropriate calculation model of CO2 emission was then built. Based on the carbon emission calculation model, the proportion of carbon emissions in each stage was analyzed. The analytic hierarchy process was used to establish the system of asphalt pavement construction with a judgment matrix, thereby enabling calculation of the weight coefficient of each link. In addition, the stages of aggregate heating, asphalt heating, and asphalt mixture mixing were defined as key stages of asphalt pavement construction. Carbon emissions at these stages accounted for approximately 90% of the total carbon emissions. Carbon emissions at each stage and their impact on the environment were quantified and compared. The energy saving construction schemes as well as the environmental and socioeconomic benefits were then proposed. Through these schemes, significant reductions in carbon emissions and costs can be achieved. The results indicate that carbon emissions reduce by 32.30% and 35.93%, whereas costs reduce by 18.58% and 6.03%. The proposed energy-saving and emission reduction scheme can provide a theoretical basis and technical support for the development of low-carbon highway construction.
Optimization of Laser Beam Transformation Hardening by One Single Parameter
Meijer, J.; Sprang, van I.
The process of laser beam transformation hardening is principally controlled by two independent parameters, the absorbed laser power on a given area and the interaction time. These parameters can be transformed into two functional parameters: the maximum surface temperature and the hardening depth.
[Hardening of dental tissue by CO2 laser radiation].
Aboites, V; Díaz, O; Cuevas, F
A study was conducted to test the effects of CO2 laser irradiation on dental tissue. It was found that hardening of the dental tissue occurs. This was observed qualitatively by direct observation and by X-ray radiography. The hardening produced was also quantitatively measured using a hardness-meter on Rockwell scale.
Hardening treatment of friction surfaces of ball journal bearings
Gorlenko, A. O.; Davidov, S. V.
The article presents the technology of finishing plasma hardening by the application of the multi-layer nanocoating Si-O-C-N system to harden the friction surfaces of the ball journal bearings. The authors of the paper have studied the applied wear-resistant anti-friction coating tribological characteristics, which determine the increase in wear resistance of the ball journal bearings.
A new viscoplastic model for the plastic stress-strain behaviour of f.c.c. metals is presented. In this model the strain hardening results from increasing dislocation densities. The observed stagnation of strain hardening after strain reversals is explained by a lowering of the increase in dislocati
Modeling of state parameter and hardening function for granular materials
Institute of Scientific and Technical Information of China (English)
彭芳乐; 李建中
A modified plastic strain energy as hardening state parameter for dense sand was proposed, based on the results from a series of drained plane strain tests on saturated dense Japanese Toyoura sand with precise stress and strain measurements along many stress paths. In addition, a unique hardening function between the plastic strain energy and the instantaneous stress path was also presented, which was independent of stress history. The proposed state parameter and hardening function was directly verified by the simple numerical integration method. It is shown that the proposed hardening function is independent of stress history and stress path and is appropriate to be used as the hardening rule in constitutive modeling for dense sand, and it is also capable of simulating the effects on the deformation characteristics of stress history and stress path for dense sand.
New analytical approach for neutron beam-hardening correction.
Hachouf, N; Kharfi, F; Hachouf, M; Boucenna, A
In neutron imaging, the beam-hardening effect has a significant effect on quantitative and qualitative image interpretation. This study aims to propose a linearization method for beam-hardening correction. The proposed method is based on a new analytical approach establishing the attenuation coefficient as a function of neutron energy. Spectrum energy shift due to beam hardening is studied on the basis of Monte Carlo N-Particle (MCNP) simulated data and the analytical data. Good agreement between MCNP and analytical values has been found. Indeed, the beam-hardening effect is well supported in the proposed method. A correction procedure is developed to correct the errors of beam-hardening effect in neutron transmission, and therefore for projection data correction. The effectiveness of this procedure is determined by its application in correcting reconstructed images. PMID:26609685
Dilatant hardening of fluid-saturated sandstone
Makhnenko, Roman Y.; Labuz, Joseph F.
The presence of pore fluid in rock affects both the elastic and inelastic deformation processes, yet laboratory testing is typically performed on dry material even though in situ the rock is often saturated. Techniques were developed for testing fluid-saturated porous rock under the limiting conditions of drained, undrained, and unjacketed response. Confined compression experiments, both conventional triaxial and plane strain, were performed on water-saturated Berea sandstone to investigate poroelastic and inelastic behavior. Measured drained response was used to calibrate an elasto-plastic constitutive model that predicts undrained inelastic deformation. The experimental data show good agreement with the model: dilatant hardening in undrained triaxial and plane strain compression tests under constant mean stress was predicted and observed.
Decision of National and Provincial Highway Asphalt Pavement Structure Based on Value Engineering
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Yingwei Ren
Full Text Available It is important that decision of asphalt pavement structure requires overall considerations of the performance and financial investment. To have asphalt pavement structure fulfilling good reliability, the asphalt pavement structure decision was researched based on value engineering theory. According to the national and provincial highway investigation data in Shandong Province during the last decade, the asphalt pavement performance attenuation rules of traffic levels and asphalt layer thicknesses were developed, and then the road performance evaluation method was presented. In addition, the initial investments, the costs of road maintenance, and middle-scale repair in a period were analyzed. For the light traffic and medium traffic example, using the value engineering method, the pavement performance and costs of which thickness varies from 6 cm to 10 cm were calculated and compared. It was concluded that value engineering was an effective method in deciding the asphalt pavement structure.
Accelerated aging of catalytically airblown asphalt membranes under simulated uranium mill tailings impoundment conditions
International Nuclear Information System (INIS)
This paper evaluates the performance of asphalt membranes by examining the chemical and permeability changes experienced by the asphalt during aging tests. The aging process was accelerated by exposing the asphalt to elevated temperatures, high oxygen concentrations, and increased strengths of aqueous oxidizing agents. The synergistic effects of the variables are evaluated by using a fractional factorial experimental design. The installation costs for a catalytically airblown asphalt liner are roughly half that of the typical polymeric materials, and also less than the rubberized asphalt membrane. The results of the initial accelerated aging tests of the asphalt membranes indicate that this material will provide stable, long-term leachate isolation in a mill tailings environment
SGC Tests for Influence of Material Composition on Compaction Characteristic of Asphalt Mixtures
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Qun Chen
Full Text Available Compaction characteristic of the surface layer asphalt mixture (13-type gradation mixture was studied using Superpave gyratory compactor (SGC simulative compaction tests. Based on analysis of densification curve of gyratory compaction, influence rules of the contents of mineral aggregates of all sizes and asphalt on compaction characteristic of asphalt mixtures were obtained. SGC Tests show that, for the mixture with a bigger content of asphalt, its density increases faster, that there is an optimal amount of fine aggregates for optimal compaction and that an appropriate amount of mineral powder will improve workability of mixtures, but overmuch mineral powder will make mixtures dry and hard. Conclusions based on SGC tests can provide basis for how to adjust material composition for improving compaction performance of asphalt mixtures, and for the designed asphalt mixture, its compaction performance can be predicted through these conclusions, which also contributes to the choice of compaction schemes.
SGC tests for influence of material composition on compaction characteristic of asphalt mixtures.
Chen, Qun; Li, Yuzhi
Compaction characteristic of the surface layer asphalt mixture (13-type gradation mixture) was studied using Superpave gyratory compactor (SGC) simulative compaction tests. Based on analysis of densification curve of gyratory compaction, influence rules of the contents of mineral aggregates of all sizes and asphalt on compaction characteristic of asphalt mixtures were obtained. SGC Tests show that, for the mixture with a bigger content of asphalt, its density increases faster, that there is an optimal amount of fine aggregates for optimal compaction and that an appropriate amount of mineral powder will improve workability of mixtures, but overmuch mineral powder will make mixtures dry and hard. Conclusions based on SGC tests can provide basis for how to adjust material composition for improving compaction performance of asphalt mixtures, and for the designed asphalt mixture, its compaction performance can be predicted through these conclusions, which also contributes to the choice of compaction schemes. PMID:23818830
Development of an innovative bio-binder using Asphalt-rubber technology
Peralta, J.; Silva, Hugo Manuel Ribeiro Dias da; Williams, R. Christopher; Rover, Marjorie; Machado, A.V.
This research work evaluates several parameters that can affect Asphalt Rubber (AR) binder performance and applies the AR technology to the development of an innovative renewable bio-binder that can fully and cost-effectively replace asphaltic bitumen derived from petroleum in flexible pavement construction. The "Binder Accelerated Separator" method was used to divide the constituents of the Asphalt Rubber and bio-binder (residual binder and swelled rubber). The physical and chemi...
Asphalt rubber interlayer benefits on reflective crack retardation of flexible pavement overlays
Shakir, Shatnawi; Pais, Jorge; Minhoto, Manuel
This paper provides an overview of the asphalt rubber interlayer benefits on reflective crack retardation in flexible pavement preservation and rehabilitation strategies. These interlayers are known in California as asphalt rubber absorbing membrane interlayers (SAMI-R) or as asphalt rubber aggregate membrane interlayers (ARAM-I) chip seals. These interlayers have been used successfully as part of cape seals and as part of an overlay system. The paper focuses on the performance in terms of fi...
Asphalt rubber interlayer benefits in minimizing reflective cracking of overlays over rigid pavements
Shatnawi, Shakir; Pais, Jorge; Minhoto, Manuel
This paper provides an overview of the asphalt rubber interlayer benefits on reflective crack retardation in overlays over rigid pavements. These interlayers are known in California as asphalt rubber absorbing membrane interlayers (SAMI-R) or as asphalt rubber aggregate membrane interlayers (ARAM-I) chip seals. The paper focuses on the performance in terms of field project reviews, laboratory performance tests and finite element analysis. SAMI-R has been given a reflective cracking equivalent...
Effect of cryogenic and ambient crushed rubber on the mechanical properties of hot mixes asphalts
Neto, Silvrano Adonias Dantas; Farias, Márcio Muniz de; Pais, Jorge C.
The crumb rubber used to produce asphalt rubber binders can be obtained either through the ambient grinding or the cryogenic processes. The final product obtained usually presents significant differences which influence the physical properties of asphalt rubber binders and, consequently, the mechanical properties of the asphalt rubber hot mixes produced with these modified binders. The objective of the study presented in this paper is to learn about the influence that the type of crumb rubber...
Recycled tyre rubber modified bitumens for road asphalt mixtures: a literature review
Lo Presti, Davide
Nowadays, only a small percentage of waste tyres are being land-filled. The Recycled Tyre Rubber is being used in new tyres, in tyre-derived fuel, in civil engineering applications and products, in moulded rubber products, in agricultural uses, recreational and sports applications and in rubber modified asphalt applications. The benefits of using rubber modified asphalts are being more widely experienced and recognized, and the incorporation of tyres into asphalt is likely to increase. The te...
Use of tire rubber to improve fatigue performance of asphalt mixtures
Thives, L. P.; Trichês, Glicério; Pereira, Paulo A. A.; Pais, Jorge C.
The accelerated failure of pavements is one of the main problems in Brazilian roads resulting from fatigue cracking due to the repeated application of traffic induced stresses. The incorporation of crumb rubber from waste tires in asphalt, named asphalt rubber, is a method which has been used in several countries to improve the properties of asphalt pavement mixtures and, at the same time, has been a ecologically alternative to deal with the proper disposal of waste tires. This...
The Research on Improvement of Low Temperature Stability for Diatomite Modified Asphalt Mixture with PE Particles
HU Qiusheng; Zhou, Gang
In light of the lake of low temperature stability for diatomaceous which used as asphalt modifier.Stat the research with the diatomite produced at Jilin Changbai, using the way of low temperature bending test to evaluate the PE and diatomite composite modified asphalt mixture's low temperature crack resistance performance. The results showed that after the diatomite and PE composite modified asphalt mixture has the best advantage of anti-cracking performance under low-temperature ...
Removal of contaminated asphalt layers by using heat generating powder metallic systems
International Nuclear Information System (INIS)
Heat generating systems on the base of powder metallic fuel were used for the removal of contaminated asphalt layers. Decontamination of spots which had complex geometric form was performed. Asphalt layers with deep contamination were removed essentially all radionuclides being retained in asphalt residue. Only a small part (1 - 2 %) of radionuclides could pass to combustion slag. No radionuclides were detected in aerosol-gas phase during decontamination process
Professionalising the asphalt construction process: aligning information technologies, operators' knowledge and laboratory practices
Bijleveld, Frank Roland
This research addresses the need to professionalise the asphalt construction process. A distinctive action research strategy is designed and carried out to progressively improve operational strategies of asphalt teams from technological, human (operator) and laboratory perspectives. Using information technologies, such as GPS, a laser-linescanner, and infrared cameras, the on-site construction process in made explicit. More than thirty asphalt construction projects are systematically monitore...
Fatigue laws for Brazilians asphalt rubber mixtures obtained in 4 point bending tests
Fontes, Liseane P. T. L.; Trichês, Glicério; Pais, Jorge C.; Pereira, Paulo A. A.
The majority of Brazilian roadpavements consistsof thin pavement structures unable to resist the damage caused by heavy loads and an increasing traffic demand. The main structural distress modes found in Brazilians asphalt layers is fatigue cracking. One of the prom-ising techniques to improve the pavement performance is through asphalt rubber mixtures, which make use of crumb rubber from scrap tires to modify and enhance the properties of the asphalt. The inexistence of fatigue laws for asph...
Effects of Crumb Rubber Size and Concentration on Performance of Porous Asphalt Mixtures
Altan Cetin
The purpose of this study is to investigate the effect of size distribution and concentration of crumb rubber on the performance characteristics of porous asphalt mixture. The recycling of scrap tires in asphalt pavements appears as an important alternative providing a large-scale market. The characteristics of bitumen are very important with regard to service life of porous asphalt pavement. The experimental study consists of two main steps. Firstly, the mixture design was performed to deter...
The reinforcement and healing of asphalt mastic mixtures by rejuvenator encapsulation in alginate compartmented fibres
Tabaković, A.; Post, W.; Cantero, D.; Copuroglu, O.; Garcia, S. J.; Schlangen, E.
This paper explores the potential use of compartmented alginate fibres as a new method of incorporating rejuvenators into asphalt pavement mixtures. The compartmented fibres are employed to locally distribute the rejuvenator and to overcome the problems associated with spherical capsules and hollow fibres. The work presents proof of concept of the encapsulation process which involved embedding the fibres into the asphalt mastic mixture and the survival rate of fibres in the asphalt mixture. To prove the effectiveness of the alginate as a rejuvenator encapsulating material and to demonstrate its ability survive asphalt production process, the fibres containing the rejuvenator were prepared and subjected to thermogravimetric analysis and uniaxial tensile test. The test results demonstrated that fibres have suitable thermal and mechanical strength to survive the asphalt mixing and compaction process. The CT scan of an asphalt mortar mix containing fibres demonstrated that fibres are present in the mix in their full length, undamaged, providing confirmation that the fibres survived the asphalt production process. In order to investigate the fibres physiological properties and ability to release the rejuvenator into cracks in the asphalt mastic, the environmental scanning electron microscope and optical microscope analysis were employed. To prove its success as an asphalt healing system, compartmented alginate fibres containing rejuvenator were embedded in asphalt mastic mix. The three point bend tests were performed on the asphalt mastic test samples and the degree to which the samples began to self-heal in response was measured and quantified. The research findings indicate that alginate fibres present a promising new approach for the development of self-healing asphalt pavement systems.
Development of asphaltic mix with waste products use
Directory of Open Access Journals (Sweden)
Pugin Konstantin Georgievich
Full Text Available The trend of high growth of the vehicle fleet in Russia along with the positive impact on the socio-economic development of the country has a number of adverse consequences, one of which is the high accident rate on the roads. The paper considers modern way to provide the safe vehicles flow with the use of colored asphalt, which is a kind of hot asphalt and can have a variety of colors, which consists of coloring pigments. The conventional method of coloring the asphalt mix is produced by adding color rubble or pigmenting additives. The task, which was put forward, was the establishment of such road concrete mix, from which, without the use of primary materials and without increasing the consumption of bitumen, asphalt concrete road surfaces of acceptable strength could be obtained. As a pigment the dust of gas purification system of electrical furnace DSP - 60 of «Kamastal» plant, Perm, was used. The composition of the dust waste from the furnace consists of metal oxides and silicates. Dust-gas-cleaning is a fine powder with a high specific surface (1.2…2.5 thousand cm /g and bulk density of 3.7…4.2 g/cm . The powder color is dark brown. The density of the ready colored asphalt samples is 2.47...2.49 g/cm , and water saturation is 3.50…3.55 %. As a result of the research the diagrams of the dependence of road concrete mix's water saturation from dust percentage and a diagram of dependence of concrete mixes' durability from dust percentage at t = 20° and 50° C were built. After analyzing the obtained curves it can be concluded that the increase of the percentage of dust leads to increase of water saturation of road concrete mix and reduced strength. Thus, the developed asphalt concrete mix allows visually separating the lanes on the road, it has the relevant regulatory requirements durability and water resistance. This mixture corresponds to the type B mark III and can be used in regions I, II, and partly III of road-climatic zones
Mechanism of Fume Suppression and Performance on Asphalt of Expanded Graphite for Pavement under High Temperature Condition
Institute of Scientific and Technical Information of China (English)
HUANG Gang; HE Zhaoyi; HUANG Yangcheng; ZHOU Chao; YUAN Xiaoya
Fume suppression mechanisms and the effect of expanded graphite on the performance of asphalt were studied by applying infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and comprehensive thermal analysis (TG, DSC). The experimental results confirm that asphalt which is mixed with expandable graphite will expand in the process of hot mix, and the expanded graphite layer will swell by the light component in the asphalt. The light component in the asphalt and PAHs adsorption on expanded graphite surface or part of the plug in the expanded graphite layer between plates made nucleation crystallization growth. And the Van der Waals force and the bonding of the lattice can effectively restrain the asphalt fume release. Meanwhile, the expanding agent with oxidative can spread into the asphalt, leading to asphalt oxygenated and plastic abate, while the ductility decreases. Expanded graphite, SBS modifier and environment- friendly plasticizers are used to composite modified asphalt. According to asphalt fume release experiment, normal test of asphalt performance, Brookfield viscosity test, RTFOT test and asphalt mixture tests (high temperature stability, low temperature stability, water stability), it has been proven that the modified asphalt's performance is better than that of matrix asphalt and equivalent to that of SBS modified asphalt. Furthermore, it has good fume suppression effect.
Directory of Open Access Journals (Sweden)
Andrzej Plewa
Full Text Available With the development of the automotive industry the disposal of used tires is constantly growing problem. Storage of waste rubber is associated with a very long period of decomposition of rubber in the natural conditions. Simultaneously new technologies are developed every year, which in the future may significantly promote recycling of this type of materials. The crumb rubbery modification of the road bitumen is the one of the environmentally safe solutions of rubbery decomposition. Improvement of resistance of the crumb rubbery modification of the road asphalt mixtures is the very important ecological aspect of the future. The article presents the results of research on the fatigue life resistance of asphalt concretes AC16P and AC22P with asphalt-rubber binders. The above analyses have been based on the results of tests of fatigue life of mineral-rubber-asphalt mixes determined by the method of prismatic four-point bending (4PB-PR. Mineral-rubber -asphalt mixes have been diversified according to the amount of the additive of rubber fines in asphalt-rubber binder. On the basis of the test results have been proven improvements functional properties mineral-rubber-asphalt mixes compared with mineral-asphalt mixes with unmodified asphalt.
Application of minerals residues in the asphalt composition; Aplicacao de residuos minerais na composicao do asfalto
Energy Technology Data Exchange (ETDEWEB)
Ribeiro, Roberto Carlos da C.; Seidl, Peter Rudolf [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Escola de Quimica; Correia, Julio Cesar Guedes [Centro de Tecnologia Mineral - CETEM, Rio de Janeiro, RJ (Brazil)
The performance of asphalt pavements depends mainly on the properties of their constituents: mineral aggregates and asphalt cement. The mineral aggregate represents about 95% in weight of asphalt mixtures having a significant influence on the properties and performance of these mixtures. Asphalt cement (CAP) corresponds to the smaller fraction but it is mainly responsible for adsorption on the mineral aggregates. The objective of this study was to evaluate the interaction between different CAPs with residues from granite saw wills in place of mineral aggregates that run up costs with extraction and processing in asphalt production. This way asphalt production costs as well as the environmental problems that are caused by mineral residue are reduced. Five different asphalt cements, referred to as A, B, C, D and E, and a granite residue were used in this work. The results indicated that the residue strongly absorbs all the CAPs that were studied; particularly CAP A, which is considered the most adequate for the production of asphalt from this residue. Preliminary tests this indicate that asphalt production can use mineral residues instead of mineral aggregates in its composition. (author)
Behavior of asphalt-rubber hot mixes obtained with high crumb rubber contents
Dantas Neto, Silvrano A.; Farias, Márcio Muniz de; Pais, Jorge C.; Pereira, Paulo A. A.; Santos, Luís Picado
This paper shows the results of a study about the mechanical behavior of dense graded asphalt-rubber hot mixes (grading envelope C of DNER-ES 313/97) prepared with two different types of asphalt-rubber binders. These asphalt-rubber binders were obtained with penetration grade asphalt (AC 50/70) mixed with 21% and 25% of crumb rubber in weight. The rubber was recycled from unserviceable tires using the ambient grinding process. Hot mixes made with the conventional binder AC 5...
Optimization of technical measures for improving high-temperature performance of asphalt-rubber mixture
Institute of Scientific and Technical Information of China (English)
Chuan Xiao; Tianqing Ling; Yanjun Qiu
Asphalt-rubber pavements often become dam-aged in high-temperature regions and appear rutted or wavy, and experience slippage. To improve the high-tem-perature performance of the asphalt-rubber mixture, tech-nical measurements, such as, the optimal adjustment of gradation, technique of composite modification, and con-trol of compaction were investigated. An optimal adjust-ment of aggregate gradation based on stone matrix asphalt improves the high-temperature stability of the asphalt-rubber mixture significantly. Through composite modifi-cation, the effect of asphalt-rubber modification was enhanced, and the dynamic stability and relative defor-mation indices of the asphalt-rubber mixture were improved significantly. Furthermore, compaction parame-ters had a significant influence on the high-temperature stability of the asphalt-rubber mixture. The rolling times for compacting the asphalt-rubber mixture should be controlled to within 18-20 round-trips at a molding tem-perature at 180 ?C;if the rolling time is a 12 round-trip, the compaction temperature of the asphalt-rubber mixture should be controlled between 180 and 190 ?C.
Influence of crumb rubber and digestion time on the asphalt rubber binders
Neto, Silvrano Adonias Dantas; Farias, Márcio Muniz de; Pais, Jorge C.; Pereira, Paulo A. A.; Sousa, Jorge B.
This paper shows the results of a study about the mechanical behavior of dense graded asphalt-rubber hot mixes prepared with two different types of asphalt-rubber binders. These asphalt-rubber binders were obtained with penetration grade asphalt (AC 50/70) mixed with 21% and 25% of crumb rubber in weight. The rubber was recycled from unserviceable tires using the ambient grinding process. Hot mixes made with the conventional binder AC 50/70 were also studied for comparison. The...
Investigation of the Physical and Molecular Properties of Asphalt Binders Processed with Used Motor Oils
Directory of Open Access Journals (Sweden)
Mohyeldin Ragab
Full Text Available In this work we investigated the performance aspects of addition of used motor oils (UMO to neat and crumb rubber modified asphalts (CRMA and related that to the change of molecular size distribution of modified asphalt's fractions; asphaltenes, saturates, naphthene aromatics, and polar aromatics. Based on the results of temperature sweep viscoelastic tests, addition of crumb rubber modifier (CRM alone or with UMO results in the formation of internal network within the modified asphalt. Based on the results of short and long term aged asphalts, the utilization of combination of UMO and CRM enhanced the aging behavior of asphalt. Bending beam rheometer was utilized to investigate the low temperature behavior of UMO modified asphalts. Based on those tests, the utilization of the UMO and CRM enhanced the low temperature properties of asphalts. Based on the results of the asphalt separation tests and the Gel Permeation Chromatography (GPC analysis, it was found that saturates and naphthene aromatics are the two asphalt fractions that have similar molecular size fractions as those of UMO. However, UMO only shifts the molecular sizes of saturates after interaction with asphalt. Results also show that polar aromatics pose higher molecular size structures than UMO.
Preparation, Characterization and Hot Storage Stability of Asphalt Modified by Waste Polyethylene Packaging
Institute of Scientific and Technical Information of China (English)
Changqing Fang; Ying Zhang; Qian yu; Xing Zhou; Dagang Guo; Ruien Yu; Min Zhang
Waste polyethylene packaging (WPE) was used to modify asphalt,and hot storage stability of the modified asphalt was studied in this paper.The morphological change and component loss of WPE modified asphalt were characterized by fluorescence microscopy,Fourier transform infrared spectroscopy (FT-IR),differential scanning calorimetry (DSC),thermogravimetry (TG) and isolation testing.In addition,the mechanism of the hot storage stability of WPE modified asphalt was discussed.The results showed that the modification of asphalt with WPE was a physical process.It was found that the filament or partly network-like structure formed in the modified asphalt system was beneficial to improving the hot storage stability.Moreover,the addition of WPE resulted in a decrease in both the light components volatilization and the macromolecules decomposition of asphalt.It was demonstrated that when the content of WPE in matrix asphalt was less than 10 wt%,the service performances of modified asphalt could be better.
The Silurian Reservoir Bed-Differentiated Asphalts in Tarim Basin and Modeling Experiments on Their Origin
Institute of Scientific and Technical Information of China (English)
刘洛夫; 刘宏江; 王洪玉; 曾溅辉
There is a type of asphalt that originated from differentiation from reservoir bed (named reservoir bed-differentiated asphalt) in the Silurian asphaltic sandstones of the Tarim Basin. These asphalts are the result of second-time charging of hydrocarbons into the Silurian reservoir, which were derived from Lower Paleozoic source rocks. Asphalt was differentiated from the reservoir bed in the hydrocarbon gathering area of secondary migration. The differen tiation is caused by changes in reservoir physical properties when pearl or chain hydrocarbons migrating through and gathering in the reservoir bed, and light components are lost and heavy ones are involved in the formation of asphalt or heavy oil. There are two kinds of occurrence of these asphalts in the Silurian system of the Tarim Basin. One is the poor heavy oil layer with lower oil saturation in trap and the other is scattered hydrocarbon distributed along the transport layer and unconformity surface. Reservoir bed-differentiated asphalts have two characteristics: total hydrocarbon content is high in extractable organic matter and the ratio of saturated to aromatic hydrocarbon is usually greater than unity. The physically modeling experiment has confirmed these characteristics and the genesis of the reservoir bed-differentiated asphalts.
The Silurian Reservoir Bed—Differentiated Asphalts in Tarim Basin and Modeling Experiments on Their Origin
Institute of Scientific and Technical Information of China (English)
刘洛夫; 刘宏江; 等
There is a type of asphalt that originated from differentiation from reservoir bed (named reservoir bed-differentiated asphalt)in the Silurian asphaltic sandstones of the Tarim Basin.These asphalts are the result of second-time charging of hydrocarbons into the Silurian reservoir,which were derived from Lower Paleozoic source rocks.Asphalt was differentiated from the reservoir bed in the hydrocarbon gathering area of secondary migration.The different-tiation is caused by changes in reservoir physical properties when pearl or chain hydrocarbons migrating through and gathering in the reservoir bed,and light components are lost and heavy ones are involved in the formation of asphalt or heavy oil.There are two kinds of occurrence of these asphalts in the Silurian system of the Tarim Basin.One is the poor heavy oil layer with lower oil saturation in trap and the other is scattered hydrocarbon distributed along the trans-port layer and unconformity surface.Reservoir bed-differentiated asphalts have two characteris-tics:total hydrocarbon content is high in extractable organic matter and the ratio of saturated to aromatic hydrocarbon is usually greater than unity.The physically modeling experiment has confirmed these characteristics and the genesis of the reservoir bed-differentiated asphalts.
Effect of ageing on rheological properties of storage-stable SBS/sulfur-modified asphalts.
Zhang, Feng; Yu, Jianying; Wu, Shaopeng
Oxidative ageing as an inevitable process in practical road paving has a great effect on the properties of polymer-modified asphalts (PMAs). In this article, the effect of short-term and long-term oxidative ageing on the rheological, physical properties and the morphology of the styrene-butadiene-styrene (SBS)- and storage-stable SBS/sulfur-modified asphalts was studied, respectively. The analysis on the rheological and physical properties of the PMAs before and after ageing showed the two major effects of ageing. On one hand, ageing prompted the degradation of polymer and increased the viscous behaviour of the modified binders, on the other, ageing changed the asphalt compositions and improved the elastic behaviour of the modified binders. The final performance of the aged binders depended on the combined effect. After ageing, the storage-stable SBS/sulfur-modified asphalts showed an obvious viscous behaviour compare with the SBS-modified asphalts and this led to an improved low-temperature creep property. The rutting resistance of the SBS-modified asphalts declined by the addition of sulfur due to the structural instability of the SBS/sulfur-modified asphalts. The rheological properties of the modified binders before and after ageing also depended strongly on the structural characteristics of SBS. The observation by using optical microscopy showed the compatibility between asphalt and SBS was improved with further ageing, especially for the storage-stable SBS/sulfur-modified asphalts. PMID:20637542
Effect of ageing on rheological properties of storage-stable SBS/sulfur-modified asphalts.
Zhang, Feng; Yu, Jianying; Wu, Shaopeng
Oxidative ageing as an inevitable process in practical road paving has a great effect on the properties of polymer-modified asphalts (PMAs). In this article, the effect of short-term and long-term oxidative ageing on the rheological, physical properties and the morphology of the styrene-butadiene-styrene (SBS)- and storage-stable SBS/sulfur-modified asphalts was studied, respectively. The analysis on the rheological and physical properties of the PMAs before and after ageing showed the two major effects of ageing. On one hand, ageing prompted the degradation of polymer and increased the viscous behaviour of the modified binders, on the other, ageing changed the asphalt compositions and improved the elastic behaviour of the modified binders. The final performance of the aged binders depended on the combined effect. After ageing, the storage-stable SBS/sulfur-modified asphalts showed an obvious viscous behaviour compare with the SBS-modified asphalts and this led to an improved low-temperature creep property. The rutting resistance of the SBS-modified asphalts declined by the addition of sulfur due to the structural instability of the SBS/sulfur-modified asphalts. The rheological properties of the modified binders before and after ageing also depended strongly on the structural characteristics of SBS. The observation by using optical microscopy showed the compatibility between asphalt and SBS was improved with further ageing, especially for the storage-stable SBS/sulfur-modified asphalts.
Laboratory and field evaluation of hot mix asphalt with high contents of reclaimed asphalt pavement
Van Winkle, Clinton Isaac
Currently in Iowa, the amount of RAP materials allowed for the surface layer is limited to 15% by weight. The objective of this project was to develop quality standards for inclusion of RAP content higher than 15% in asphalt mixtures. To meet Superpave mix design requirements, it was necessary to fractionate the RAP materials. Based on the extensive sieve-by-sieve analysis of RAP materials, the optimum sieve size to fractionate RAP materials was identified. To determine if the higher percentage of RAP materials than 15% can be used in Iowa's state highway, three test sections with 30.0%, 35.5% and 39.2% of RAP materials were constructed on Highway 6 in Iowa City. The construction of the field test sections was monitored and the cores were obtained to measure field densities of test sections. Field mixtures collected from test sections were compacted in the laboratory in order to test the moisture sensitivity using a Hamburg Wheel Tracking Device. The binder was extracted from the field mixtures with varying amounts of RAP materials and tested to determine the effects of RAP materials on the PG grade of a virgin binder. Field cores were taken from the various mix designs to determine the percent density of each test section. A condition survey of the test sections was then performed to evaluate the short-term performance.
Surface modification on PMMA : PVDF polyblend: hardening under chemical environment
Indian Academy of Sciences (India)
R Bajpai; V Mishra; Pragyesh Agrawal; S C Datt
The influence of chemical environment on polymers include the surface alteration as well as other deep modifications in surface layers. The surface hardening, as an effect of organic liquids on poly(methyl methacrylate): poly(vinylidene fluoride) (PMMA: PVDF), which is one of the few known miscible blends, has been detected using microhardness testing. Organic liquids like acetone, toluene, xylene and benzene were introduced on the surface of blend specimens for different durations. Vickers microhardness (v) was measured for treated and untreated specimens. The study reveals both hardening and plasticization of specimens at different exposure times. The degree of surface hardening is maximum under acetone treatment. All the specimens exhibit surface hardening at an exposure time of 1 h with all the four liquids. This feature is prominent with longer exposures for specimens with increasing content of PVDF. However, the degree of hardening decreases with the time of exposure in the respective environments. In general, acetone and toluene impart surface hardening, whereas, xylene and benzene soften the specimen. PMMA: PVDF (83 : 17) blend exhibits surface hardening under all the four treatments when compared with the respective untreated specimens.
Tailored work hardening descriptions in simulation of sheet metal forming
Vegter, Henk; Mulder, Hans.; van Liempt, Peter; Heijne, Jan
In the previous decades much attention has been given on an accurate material description, especially for simulations at the design stage of new models in the automotive industry. Improvements lead to shorter design times and a better tailored use of material. It also contributed to the design and optimization of new materials. The current description of plastic material behaviour in simulation models of sheet metal forming is covered by a hardening curve and a yield surface. In this paper the focus will be on modelling of work hardening for advanced high strength steels considering the requirements of present applications. Nowadays work hardening models need to include the effect of hard phases in a soft matrix and the effect of strain rate and temperature on work hardening. Most material tests to characterize work hardening are only applicable to low strains whereas many practical applications require hardening data at relatively high strains. Therefore, physically based hardening descriptions are needed allowing reliable extensions to high strain values.
Shakedown analysis of anisotropic asphalt concrete pavements with clay subgrade
Energy Technology Data Exchange (ETDEWEB)
Boulbibane, M.; Collins, I.F. [Auckland Univ., Auckland (New Zealand). Dept. of Engineering Science; Weichert, D. [RWTH-Aachen Inst. of General Mechanics, Aachen (Germany); Raad, L. [Alaska-Fairbanks Univ., Fairbanks, AK (United States). Transportation and Research Centre
A mathematical model has been presented which can predict the effect of inherent anisotropic cohesion on the long-term behaviour of multilayered pavements. The model is based on the lower bound theorem of shakedown analysis and makes allowances for variations of soil strength with direction. Pavements operating above the critical shakedown load exhibit plastic strains under long term repeated loading conditions and eventually result in deep ruts. This model was used to examine the influence of subgrade properties on the shakedown behaviour of two-layer pavement systems consisting of an asphalt concrete layer and a granular base over a clay subgrade. The shakedown load for pavements under repeated loadings was estimated and the effects of variables such as temperature, asphalt thickness, stiffness and strength were determined. The materials in the various layers of the pavement were modeled as elastic-plastic Mohr-Coulomb materials. 38 refs., 3 tabs., 5 figs.
Decontamination by shotblasting of radioactivity deposited on an asphalt road
International Nuclear Information System (INIS)
Long-lived fission products may be deposited in the environment after a serious reactor accident. From previous experiments it is known that if firehosing is to be used for decontamination it has to be done soon after the deposition. It is therefore worthwhile to study another decontamination method. An experimental study has been conducted of how well shotblasting can remove contamination from an asphalt road. In shotblasting a thin layer of the surface is loosened by the impact of small steel balls, and in the same procedure the surface dust is vacuumed up and the steel balls recovered. The contaminant was 86Rb, which behaves as caesium. As reference, the weathering of identical contamination on an asphalt road, a concrete road and a road covered with small concrete stones was studied concurrently. (author)
10CFR61 waste form conformance program for asphalted radwaste
International Nuclear Information System (INIS)
With the enactment of Title 10, Code of Federal Regulations, Part 61, ''Licensing Requirements for Land Disposal of Radioactive Waste'' came the imposition of new requirements on licensees who dispose of radioactive waste via shallow land burial. Specifically, 10CFR61 both imposed a waste classification system requiring segregation of waste according to hazard and established waste performance characteristics required to enhance stability of the burial site. In order to provide licensees with guidance regarding implementation of applicable requirements of 10CFR61, the NRC Low Level Waste Licensing Branch issued two Technical Positions. To demonstrate compliance of asphalted radwaste produced with oxidized asphalt with 10CRF61 criteria and the NRC's Technical Position, five utilities combined resources. The five utilities sponsoring the program were Public Service Electric and Gas Company, Niagara Mohawk Power Company, Detroit Edison Company, New Hampshire Yankee, and Consumers Power Company
Integrated coke, asphalt and jet fuel production process and apparatus
Shang, Jer Y.
A process and apparatus for the production of coke, asphalt and jet fuel m a feed of fossil fuels containing volatile carbon compounds therein is disclosed. The process includes the steps of pyrolyzing the feed in an entrained bed pyrolyzing means, separating the volatile pyrolysis products from the solid pyrolysis products removing at least one coke from the solid pyrolysis products, fractionating the volatile pyrolysis products to produce an overhead stream and a bottom stream which is useful as asphalt for road pavement, condensing the overhead stream to produce a condensed liquid fraction and a noncondensable, gaseous fraction, and removing water from the condensed liquid fraction to produce a jet fuel-containing product. The disclosed apparatus is useful for practicing the foregoing process. the process provides a useful method of mass producing and jet fuels from materials such as coal, oil shale and tar sands.
New method to quantitatively evaluate the homogeneity of asphalt mixtures
Institute of Scientific and Technical Information of China (English)
WU Wen-liang; ZHANG Xiao-ning; WANG Duan-yi; LI Zhi
To evaluate the homogeneity of asphalt mixtures, the images of sections obtained by cutting the as-phah mixtures specimen horizontally or vertically were analyzed with digital image processing techniques, and the particle area ratio was achieved by applying sector scan for horizontal specimen and vertical scan for vertical one. The research result indicates that the influence of random distribution of aggregates in cutting the specimen can be eliminated by using colored aggregates to distinguish coarse and fine aggregates and using color threshold to segment the images. Choosing three typical gradations, proving particle area ratio obeying normal distribution and using the variability of particle area ratio as an index, it is feasible to quantitatively evaluate the homogenei-ty of asphalt mixtures.
Utilisation of sinter-hardening treatment for various sintered steels
Directory of Open Access Journals (Sweden)
L.A. Dobrzański
Full Text Available Purpose: Purpose of this paper was to present the benefits of powder metallurgy technology and development of sinter-hardening process applied to different steels including pre-alloyed Ni-Mo steels with W addition, Astaloy CrM and experimental sintered duplex stainless steels. The mechanical properties, focusing in particular on hardness and wear resistance, of two different sinter-hardened steels were described. Microstructure characteristic of produced sinter-hardened steels was taken under consideration.Design/methodology/approach: Different compositions have been tested in order to investigate the influence of sinter-hardening of steels under different cooling rates on microstructure and properties. As a first group of materials Ni-Mo pre-alloyed steel powders were used, differing with the addition of tungsten and amount of carbon. Green compacts were sintered at the temperature 1120ºC for 1 hour. The next set of investigated materials was produced by mixing the Astaloy CrM powder with carbon amount of 0.6% and then compacted and sintered in the same conditions. Under sinter-hardened conditions, experimental sintered duplex stainless steels were also evaluated. After sintering, different cooling rates were applied.Findings: The applied sinter-hardening process resulted with achievement of material characterized by proper microstructure. The investigation of sinter-hardened steels proved that applied process of sintering under vacuum and rapid cooling brought expected outcome.Research limitations/implications: Considering the achieved outcome, it was revealed that chemical composition and applied process of steels preparation, sinter-hardening with rapid cooling, results in achievement of materials with relatively high apparent hardness and significant resistance to abrasion. Anyhow, further researches should be performed.Originality/value: The paper contributes to better understanding advantages of sinter-hardening process applicable to
Evidence of Multi-Stage Hydrocarbon Charging and Biodegradation of the Silurian Asphaltic Sandstones in the Tarim Basin, China
Institute of Scientific and Technical Information of China (English)
Asphalts distributed widely in the Silurian sandstones of the Tarim Basin include dry asphalt, soft asphalt and heavy oil. These asphaltic sandstones underwent multi-episodic sedimentary and tectonic events, and their occurrence is diverse and complex, being mixed with normal oil usually. So far, very little work has been done on the asphaltic sandstone origin and hydrocarbon charging ages. After detailed study on the Silurian sandstones, the following highlights were obtained from the analytical results: distribution of the mixed asphalt, heavy oil and normal oil in the Silurian sandstones is the result of multi-stage hydrocarbon charging from the Lower Paleozoic marine source rocks; the characters of asphalts formed from oils of different charging ages are of difference; the most important process constraining.the asphaltic sandstone origin is thought to be biodegradation.
Assessment of asphalt mixtures characteristics through GPR testing
Pais, Jorge; Fernandes, Francisco
Road pavements are composed by granular and asphalt layers, placed over the pavement subgrade, which are designed to resist to traffic and climatic effects. Pavement distresses include permanent deformation mainly due to the contribution of the subgrade and fatigue cracking in the asphalt layers. Fatigue cracking is the main pavement distress and is responsible for the main rehabilitations carried out in road pavements which leads, in most cases, to the pavement reconstruction due to the severity of the cracking observed in many roads. For a given aggregate gradation, the fatigue cracking resistance is related to the proportions of the components in the asphalt mixtures, namely the void content and the binder content. Also the presence of water, or moisture, has an important influence in the fatigue resistance, and its effect is characterized by a reduction in the fatigue cracking resistance. The characteristics of the asphalt mixtures applied in road pavements can be assessed in laboratory through the testing of cores extracted from the pavement. These cores are extracted some representative section of the pavement, usually equally spaced in the road. Due to the construction process, the representative sections of the pavement don't allow to identify the quality of the whole pavement. Thus, the use of continuous measurement is essential to ensure the perfect assessment of the pavement quality and the use of the GPR assumes a paramount importance. Thus, this communication presents several GPR tests carried out on pavement slabs produced in laboratory with different void content, binder content and moisture content in order to establish different classifiers that will allow the identification of this condition during regular inspections. Furthermore, tests carried on specimens before and after fatigue tests will allow to calculate similar parameters to estimate the state of conservation of pavements in terms of stiffness and the presence of cracks. This work is a
Mandula, Jan; Olexa, Tomaš; Holubka, Mariya; Salaiova, Brigita
Waste tires must be recycled in environmentally safe ways that meet civil engineering concerns while fulfilling standards for construction materials. Used tires can be processed into rubber powders with particle sizes of 0–2 mm, a suitable fine aggregate for mixing into road pavements. We tested asphalt mixtures with rubber added using the dry method, comparing their properties with a traditional mixture. We tested asphalt–rubber mixtures with rubber incorporated at either ambient temperature...
New experimental methods to monitor and characterize asphalt rubber binders
Peralta, J.; Silva, Hugo Manuel Ribeiro Dias da; Pais, Jorge C.
The need for continuous quality improvement of the road pavements, leads to the development of new binders, such as asphalt rubber (AR). AR is produced by the digestion of crumb rubber from used tires on bitumen. The resulting AR is a heterogeneous material with high viscosity. The study of this product during its production is essential due to the sudden and sharp increase in the volume of AR in this phase. Knowledge of the extent of this phenomenon has obvious implications in...
Improvement of the functional pavement quality with asphalt rubber mixtures
Fontes, Liseane P. T. L.; Pereira, Paulo A. A.; Pais, Jorge C.; Trichês, Glicério
Skid resistance and texture are important safety characteristics which need to be considered in flexible pavement design, maintenance and rehabilitation. The main objective of this paper is to optimize surface texture characteristics in asphalt rubber pavements, mainly macrotexture to reduce splash, spray and hydroplaning and microtexture to increase friction at low and high speeds. The objective was accomplished by measuring the friction surface with two different tests: (i) B...
Production technologies and analysis of use of rubberised asphalt
Pevec, Rok
Used tires present a major enviormental problem worldwide since most of them are burned as fuel in the cement industry, but most of them lie illegally in landfills in nature. It is identified and confirmed in practice that the properties of bituminous binder, to which rubber particles, which are the product of recycling waste automobile and truck tires, are added, and consequently also the properties of asphalt mixtures are significantly improved. Research in this area and the ...
Evaluation of nuclear asphalt-content gauges. Final report
International Nuclear Information System (INIS)
The study evaluated the accuracy and precision of the Troxler, Model 3241-C, and CPN, Model AC-2, Nuclear Asphalt Content Gauges. To achieve precisions at plus or minus 0.15% 95% of the time, it was necessary to establish special procedures for making test samples, controlling environment, and calibration. Both gauges provided acceptable results utilizing a 3-point calibration. Their use in the field would be acceptable when the proper procedures are followed
Structural Design of Asphalt Pavement for Low Cost Rural Roads
Institute of Scientific and Technical Information of China (English)
Yuan Goulin; Chen Rongshen
On the basis of the equivalent axle load action frequency, the traffic classifications of rural roads as well as their corresponding types are classified. The asphalt pavement structure, road surface types and thickness of the rural roads are suggested for the various action frequency of the equivalent axle load. Furthermore, the roadbase thickness graphs are provided according to different equivalent axle load action frequency with different roadbed modulus and road surface modulus taken into account.
Factory performance evaluations of engineering controls for asphalt paving equipment.
Mead, K R; Mickelsen, R L; Brumagin, T E
This article describes a unique analytical tool to assist the development and implementation of engineering controls for the asphalt paving industry. Through an agreement with the U.S. Department of Transportation, the National Asphalt Pavement Association (NAPA) requested that the National Institute for Occupational Safety and Health (NIOSH) assist U.S. manufacturers of asphalt paving equipment with the development and evaluation of engineering controls. The intended function of the controls was to capture and remove asphalt emissions generated during the paving process. NIOSH engineers developed a protocol to evaluate prototype engineering controls using qualitative smoke and quantitative tracer gas methods. Video recordings documented each prototype's ability to capture theatrical smoke under "managed" indoor conditions. Sulfur hexafluoride (SF6), released as a tracer gas, enabled quantification of the capture efficiency and exhaust flow rate for each prototype. During indoor evaluations, individual prototypes' capture efficiencies averaged from 7 percent to 100 percent. Outdoor evaluations resulted in average capture efficiencies ranging from 81 percent down to 1 percent as wind gusts disrupted the ability of the controls to capture the SF6. The tracer gas testing protocol successfully revealed deficiencies in prototype designs which otherwise may have gone undetected. It also showed that the combination of a good enclosure and higher exhaust ventilation rate provided the highest capture efficiency. Some manufacturers used the stationary evaluation results to compare performances among multiple hood designs. All the manufacturers identified areas where their prototype designs were susceptible to cross-draft interferences. These stationary performance evaluations proved to be a valuable method to identify strengths and weaknesses in individual designs and subsequently optimize those designs prior to expensive analytical field studies. PMID:10462852
Analyzing the influence of manufacturing conditions of reclaimed asphalt concrete on the characteristics of the asphalt binder: development of a gradual binder extraction method
Navaro, J.; Bruneau, D.; Drouadaine, I.; Pouteau, B.; Colin, J.; Dony, A.
When asphalt concrete is manufactured incorporating a high percentage (almost 70%) of reclaimed materials from the deconstruction of road surfaces under renovation, and when the corresponding production device is designed specifically to reduce the energy input need (lowering the production temperature), the resulting manufacturing process contributes to the protection of the environment and reduces production costs. However, to meet the quality requirements of the finished product, virgin materials of appropriate quality and quantity must also be added (mineral aggregates and new asphalt binder) and control systems set up to quantify and optimize the parameters involved (thus avoiding the guess work which still often prevails today). It was for this reason that a new experimental technique described here was devised, which will ultimately be used in asphalt concrete production plants. The technique involves lixiviating reclaimed asphalt concrete using a chlorinated solvent; the resulting solute is collected gradually, then the mixture of binders (virgin and reclaimed asphalt concrete) can be characterized and their mass fractions quantified using a combination of UV and IR spectrometry. With this experimental technique we were able to assess the extent to which the reclaimed asphalt pavement binder participates in the agglomeration and cohesion of the reclaimed asphalt concrete. This assessment was made in terms of the main parameters in the production process, temperature of the materials and mixing time.
Institute of Scientific and Technical Information of China (English)
LIUTeng-xi; HUANGShi-qing; FUYi-ming
A dimensionless stress yield criterion is proposed to describe the mixed hardening of orthortropic material ,including kinematic hardening and proportional hardening,and the associated plastic flow law is derived.The generalized effective stress-strain formulae can be obtained correspondingly based on the experimental stress-strain curves in various simple stress states.The initial plastic anisotropy is influenced by the elastic anisotropy.The yield criterion can be reduced to Huber-Mises Criterion for isotropic materials and associated constitutive equations can be degenerated into Prandtl-Reuss equations.
Institute of Scientific and Technical Information of China (English)
刘腾喜; 黄世清; 傅衣铭
A dimensionless stress yield criterion is proposed to describe the mixed hardening of orthotropic material, including kinematic hardening and proportional hardening, and the associated plastic flow law is derived. The generalized effective stress-strain formulae can be obtained correspondingly based on the experimental stress-strain curves in various simple stress states. The initial plastic anisotropy is influenced by the elastic anisotropy. The yield criterion can be reduced to Huber-Mises Criterion for isotropic materials and associated constitutive equations can be degenerated into Prandtl-Reuss equations.
Properties of modified anhydride hardener and its cured resin
Qiang, Chen; Bingjun, Gao; Jinglin, Chen; Tongzhao, Xu
Methyl-nadic-tetrahydric-methylanhydride (MNA), nadic-tetrahydric-methylanhydride (NA), anhydride hardener was modified by solid diol molecule to improve the impregnation resin fracture toughness in cryogenic temperature. The lap-shear strength, transverse tension as well as the thermal shock test showed that the resin cured by the modified anhydride hardener had higher bond strength and more toughness at 77 K. After the experiment of vacuum pressure impregnation (VPI) processing, it was found that this resin had a longer usable life, better impregnating properties, but higher initial viscosity than the resin hybrid HY925 as hardener.
Strain hardening of metal parts with use of impulse wave
Kirichek, A. V.; Soloviev, D. L.
This work describes a strain hardening method with the use of impulse waves. This method increases energy transfer to the strained material extending its technological capabilities with development of a deep strengthened layer and allowing formation of a heterogeneous hardened structure using plastic deformation. This structure has specified distribution of the hard and soft (visco-plastic) areas. Due to development of the heterogeneous structure in the surface layer created by strain hardening with impulse wave, durability of parts that suffer contact fatigue loading is significantly increased.
Representative volume element of asphalt pavement for electromagnetic measurements
Directory of Open Access Journals (Sweden)
Terhi Pellinen
Full Text Available The motivation for this study was to investigate the representative volume element (RVE needed to correlate the nondestructive electromagnetic (EM measurements with the conventional destructive asphalt pavement quality control measurements. A large pavement rehabilitation contract was used as the test site for the experiment. Pavement cores were drilled from the same locations where the stationary and continuous Ground Penetrating Radar (GPR measurements were obtained. Laboratory measurements included testing the bulk density of cores using two methods, the surface-saturated dry method and determining bulk density by dimensions. Also, Vector Network Analyzer (VNA and the through specimen transmission configuration were employed at microwave frequencies to measure the reference dielectric constant of cores using two different footprint areas and therefore volume elements. The RVE for EM measurements turns out to be frequency dependent; therefore in addition to being dependent on asphalt mixture type and method of obtaining bulk density, it is dependent on the resolution of the EM method used. Then, although the average bulk property results agreed with theoretical formulations of higher core air void content giving a lower dielectric constant, for the individual cores there was no correlation for the VNA measurements because the volume element seizes deviated. Similarly, GPR technique was unable to capture the spatial variation of pavement air voids measured from the 150-mm drill cores. More research is needed to determine the usable RVE for asphalt.
Evaluation of Colemanite Waste as Aggregate Hot Mix Asphalt Concrete
Directory of Open Access Journals (Sweden)
Nihat MOROVA
Full Text Available In this study usability of waste colemanite which is obtained after cutting block colemanite for giving proper shape to blocks as an aggregate in hot mix asphalt. For this aim asphalt concrete samples were prepared with four different aggregate groups and optimum bitumen content was determined. First of all only limestone was used as an aggregate. After that, only colemanite aggregate was used with same aggregate gradation. Then, the next step of the study, Marshall samples were produced by changing coarse and fine aggregate gradation as limestone and colemanite and Marshall test were conducted. When evaluated the results samples which produced with only limestone aggregate gave the maximum Marshall Stability value. When handled other mixture groups (Only colemanite, colemanite as coarse aggregate-limestone as fine aggregate, colemanite as fine aggregate-limestone as coarse aggregate all groups were verified specification limits. As a result, especially in areas where there is widespread colemanite waste, if transportation costs did not exceed the cost of limestone, colemanite stone waste could be used instead of limestone in asphalt concrete mixtures as fine aggregate
Energy and exergy analysis in an asphalt plant's rotary dryer
International Nuclear Information System (INIS)
In this paper, energy and exergy analyses of a rotary dryer employed in a Hot Mix Asphalt (HMA) plant for heating and drying of the aggregates in the mixture is presented. In the analysis, the exergy method in addition to the more conventional energy analysis, is employed to identify and evaluate the thermodynamic losses. The results show that, at design conditions, the plant performs with energy and exergy efficiencies of 0.89 and 0.18, respectively. The energy losses are mainly due to the flue gases. The exergy distribution indicates that the combustion and the heat transfer at different temperatures in the burner yield the highest exergy destruction in the process. A parametric study is conducted for the plant under various operational production parameters, including different humidities of the aggregates and filler content in aggregates, working temperatures and ambient conditions, in order to determine the parameters that affect the plant performance. It is shown that the solids humidity has a great impact on energy requirements. A better and sustainable use of the heat source employed in the dryer is proposed to avoid the high irreversibilities found. Furthermore, operating corrections in the mix or in the exhaust gas temperature are proposed to optimize the performance of the plant. - Research highlights: → Identify main energy losses and irreversibilities in the dryer of an asphalt plant. → Optimize operating conditions in an Asphalt plant. → Improve energy savings and availability of the drying and heating process. → Encourage the use of a cogeneration system.
Use of steel slag aggregate in asphalt concrete mixes
Energy Technology Data Exchange (ETDEWEB)
Asi, I.M.; Qasrawi, Y.; Shalabi, F.I. [Hashemite Univ., Zarqa (Jordan). Dept. of Civil Engineering
The physical, chemical and mechanical properties of generated steel slag aggregates (SSA) were studied in order to investigate their potential use in asphalt concrete (AC) mixes. Five AC mixes were investigated, notably an AC mix with a 100 per cent limestone aggregate, and mixes comprised of 25, 50, 75, and 100 per cent SSA coarse aggregates. A superpave mix design was used to determine optimum asphalt content (OAC). Steps included the selection of a design aggregate structure, optimization of the asphalt content for the structure, and an evaluation of the moisture sensitivity of the design mixture. The effectiveness of the samples were assessed by their ability to improve indirect tensile strength (ITS); resilient and creep modulus; fatigue life; and stripping and rutting resistance. Various AC mixes containing the SSA were then evaluated. A gyratory compactor was used to compact the test samples, which were then subjected to comprehensive mechanical evaluations. Statistical analyses were then performed to examine the significance of the SSA percentage in the changing ITS values using analysis of variance (ANOVA) calculations. Results of the study indicated that SSA met both superpave consensus properties and Jordanian standards source properties. Chemical and toxic levels were within allowable limits. It was concluded that optimal the replacement percentage of SSA was 25 per cent. 18 refs., 9 tabs., 21 figs.
Airborne exposures to PAH and PM2.5 particles for road paving workers applying conventional asphalt and crumb rubber modified asphalt.
Watts, R R; Wallingford, K M; Williams, R W; House, D E; Lewtas, J
Personal exposure monitoring was conducted for road paving workers in three states. A research objective was to characterize and compare occupational exposures to fine respirable particles (asphalt and asphalt containing crumb rubber from shredded tires. Workers not exposed to asphalt fume were also included for comparison (to support the biomarker component of this study). The rubber content of the crumb rubber modified (CRM) asphalt at the three study sites was 12, 15, and 20%. A comparison of some specific job categories from two sites indicates greater potential carcinogenic PAH exposures during CRM asphalt work, however, the site with the greatest overall exposures did not indicate any differences for specific jobs. A statistical analysis of means for fine particle, pyrene and total carcinogenic PAH personal exposure shows, with two exceptions, there were no differences in exposures for these three measurement variables. One site shows significantly elevated pyrene exposure for CRM asphalt workers and another site similarly shows greater carcinogenic PAH exposure for CRM asphalt workers. Conventional and CRM asphalt worker airborne exposures to the PAH carcinogen marker, BaP, were very low with concentrations comparable to ambient air in many cities. However, this study demonstrates that asphalt road paving workers are exposed to elevated airborne concentrations of a group of unknown compounds that likely consist of the carcinogenic PAHs benz(a)anthracene, chrysene and methylated derivatives of both. The research described in this article has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. PMID:9577752
Cyber situational awareness and differential hardening
Dwivedi, Anurag; Tebben, Dan
The advent of cyber threats has created a need for a new network planning, design, architecture, operations, control, situational awareness, management, and maintenance paradigms. Primary considerations include the ability to assess cyber attack resiliency of the network, and rapidly detect, isolate, and operate during deliberate simultaneous attacks against the network nodes and links. Legacy network planning relied on automatic protection of a network in the event of a single fault or a very few simultaneous faults in mesh networks, but in the future it must be augmented to include improved network resiliency and vulnerability awareness to cyber attacks. Ability to design a resilient network requires the development of methods to define, and quantify the network resiliency to attacks, and to be able to develop new optimization strategies for maintaining operations in the midst of these newly emerging cyber threats. Ways to quantify resiliency, and its use in visualizing cyber vulnerability awareness and in identifying node or link criticality, are presented in the current work, as well as a methodology of differential network hardening based on the criticality profile of cyber network components.
Novel SEU hardened PD SOI SRAM cell
Institute of Scientific and Technical Information of China (English)
Xie Chengmin; Wang Zhongfang; Wang Xihu; Wu Longsheng; Liu Youbao
A novel SEU hardened 10T PD SOI SRAM cell is proposed.By dividing each pull-up and pull-down transistor in the cross-coupled inverters into two cascaded transistors,this cell suppresses the parasitic BJT and source-drain penetration charge collection effect in PD SOl transistor which causes the SEU in PD SOI SRAM.Mixed-mode simulation shows that this novel cell completely solves the SEU,where the ion affects the single transistor.Through analysis of the upset mechanism of this novel cell,SEU performance is roughly equal to the multiple-cell upset performance of a normal 6T SOI SRAM and it is thought that the SEU performance is 17 times greater than traditional 6T SRAM in 45nm PD SOI technology node based on the tested data of the references.To achieve this,the new cell adds four transistors and has a 43.4% area overhead and performance penalty.
Durability of High Performance Color Hardener
Institute of Scientific and Technical Information of China (English)
MA Bao-guo; DONG Rong-zhen; ZHU Hong-bo; ZHANG Li; JIAN Shou-wei
The properties of high performance color hardener (HPCH) and the mechanism were studied.HPCH is a composite system, which is composed of cementitious and auxiliary cementing materials, composite additives, abrasion resistance component (aggregate) and pigment. The porosity and pore structure of the material are obviously improved due to the activation, filling and adsorption of auxiliary cementing materials, thus resulting in a great increase of binding capacity for ions in HPCH and the obstacles of ion migrating.The density of material structure, bonding capacity of cementitious material to the abrasion-resisting component and the corrosion resistance are greatly and effectively improved by adding the auxiliary cementing materials and compound additives. According to the tests of dry shrinkage, sulphate resistance, chloride permeability and Ca(OH)2 content distribution, the property superiority of HPCH is analyzed.The mechanism of materials modification of HPCH is explained from the microscopic point of view by testing the pore structure and pore distribution via the mercury intrusion pressure method.
77 FR 50651 - Approval and Promulgation of Air Quality Implementation Plans; New Hampshire; Hot Mix Asphalt Plants
... Mix Asphalt Plants AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. SUMMARY: EPA... Hampshire Hot Mix Asphalt Plant Rule at Env-A 2703.02(a). This rule establishes and requires limitations on visible emissions from all hot mix asphalt plants. This revision is consistent with the maintenance of...
Thermal behavior of crumb-rubber modified asphalt concrete mixtures
Epps, Amy Louise
Thermal cracking is one of the primary forms of distress in asphalt concrete pavements, resulting from either a single drop in temperature to an extreme low or from multiple temperature cycles above the fracture temperature of the asphalt-aggregate mixture. The first mode described is low temperature cracking; the second is thermal fatigue. The addition of crumb-rubber, manufactured from scrap tires, to the binder in asphalt concrete pavements has been suggested to minimize both types of thermal cracking. Four experiments were designed and completed to evaluate the thermal behavior of crumb-rubber modified (CRM) asphalt-aggregate mixtures. Modified and unmodified mixture response to thermal stresses was measured in four laboratory tests. The Thermal Stress Restrained Specimen Test (TSRST) and the Indirect Tensile Test (IDT) were used to compare mixture resistance to low temperature cracking. Modified mixtures showed improved performance, and cooling rate did not affect mixture resistance according to the statistical analysis. Therefore results from tests with faster rates can predict performance under slower field rates. In comparison, predicted fracture temperatures and stresses (IDT) were generally higher than measured values (TSRST). In addition, predicted fracture temperatures from binder test results demonstrated that binder testing alone is not sufficient to evaluate CRM mixtures. Thermal fatigue was explored in the third experiment using conventional load-induced fatigue tests with conditions selected to simulate daily temperature fluctuations. Test results indicated that thermal fatigue may contribute to transverse cracking in asphalt pavements. Both unmodified and modified mixtures had a finite capacity to withstand daily temperature fluctuations coupled with cold temperatures. Modified mixtures again exhibited improved performance. The fourth experiment examined fracture properties of modified and unmodified mixtures using a common fracture toughness test
Properties of sodium silicate bonded sand hardened by microwave heating
Institute of Scientific and Technical Information of China (English)
Wang Jina; Fan Zitian; Zan Xiaolei; Pan Di
The sodium silicate bonded sand hardened by microwave heating has many advantages,such as low sodium silicate adding quantity,fast hardening speed,high room temperature strength,good collapsibility and certain surface stability. However,it has big moisture absorbability in the air,which would lead to the compression strength and the surface stability of the sand molds being sharply reduced. In this study,the moisture absorbability of the sodium silicate bonded sand hardened by microwave heating in different humidity conditions and the effect factors were investigated. Meanwhile,the reasons for the big moisture absorbability of the sand were analyzed.Some measures to overcome the problems of high moisture absorbability,bad surface stability and sharply reducing strength in the air were discussed. The results of this study establish the foundation of green and clean foundry technology based on the microwave heating hardening sodium silicate sand process.
Space Qualified, Radiation Hardened, Dense Monolithic Flash Memory Project
National Aeronautics and Space Administration — Radiation hardened nonvolatile memories for space is still primarily confined to EEPROM. There is high density effective or cost effective NVM solution available to...
Radiation Hardened Ethernet PHY and Switch Fabric Project
National Aeronautics and Space Administration — Innoflight will develop a new family of radiation hardened (up to 3 Mrad(Si)), fault-tolerant, high data-rate (up to 8 Gbps), low power Gigabit Ethernet PHY and...
Ultimate Bending Capacity of Strain Hardening Steel Pipes
Institute of Scientific and Technical Information of China (English)
陈严飞; 张娟; 张宏; 李昕; 周晶; 曹静
Based on Hencky's total strain theory of plasticity, ultimate bending capacity of steel pipes can be determined analytically assuming an elastic-linear strain hardening material, the simplified analytical solution is proposed as well. Good agreement is observed when ultimate bending capacities obtained from analytical solutions are compared with experimental results from full-size tests of steel pipes. Parametric study conducted as part of this paper indicates that the strain hardening effect has significant influence on the ultimate bending capacity of steel pipes. It is shown that pipe considering strain hardening yields higher bending capacity than that of pipe assumed as elastic-perfectly plastic material. Thus, the ignorance of strain hardening effect, as commonly assumed in current codes, may underestimate the ultimate bending capacity of steel pipes. The solutions proposed in this paper are applicable in the design of offshore/onshore steel pipes, supports of offshore platforms and other tubular structural steel members.
Space Qualified, Radiation Hardened, Dense Monolithic Flash Memory Project
National Aeronautics and Space Administration — Space Micro proposes to build a radiation hardened by design (RHBD) flash memory, using a modified version of our RH-eDRAM Memory Controller to solve all the single...
Technologies Enabling Custom Radiation-Hardened Component Development Project
National Aeronautics and Space Administration — Two primary paths are available for the creation of a Rad-Hard ASIC. The first approach is to use a radiation hardened process such as existing Rad-Hard foundries....
Hardening in Two-Phase Materials. II. Plastic Strain and Mean Stress Hardening Rate
DEFF Research Database (Denmark)
Lilholt, Hans
The strain parameters which are relevant in a tensile experiment, are analysed and related to the geometry of deformation and to the mean stress of two-phase materials. The hardening rate of the mean stress with respect to plastic strain is found to be useful in comparison between experiments...... and theories, and it allows theories to be probed over a range of strains. Previous experiments on the fibre-reinforced material of copper-tungsten are analysed in relation to the geometry of deformation....
Prediction Of Mechanical Properties Of Quench Hardening Steel*
Chotěborský R.; Linda M.
The present study investigated the application of finite element method for prediction of mechanical properties of quench hardening steel. Based on the experimental results obtained, a numerical model for simulation of continuous cooling of quench hardening steel was developed. For the simulation of the kinetics of diffusion phase transformations, the Avrami equation and additive rule were applied. A new model was also developed for martensitic transformation which was validated using metallo...
DMILL circuits. The hardened electronics decuples its performances
International Nuclear Information System (INIS)
Thanks to the DMILL (mixed logic-linear hardening) technology under development at the CEA, MHS, a French company specialized in the fabrication of integrated circuits now produces hardened electronic circuits ten times more resistant to radiations than its competitors. Outside the initial market (several thousands of circuits for the LHC particle accelerator of Geneva), a broad choice of applications is opened to this technology: national defense, space, civil nuclear and medical engineering, and high temperature applications. Short paper. (J.S.)
40 CFR Table 1 of Subpart Aaaaaaa... - Emission Limits for Asphalt Processing (Refining) Operations
... following emission limits * * * 1. Blowing stills a. Limit PAH emissions to 0.003 lb/ton of asphalt charged to the blowing stills;or b. Limit PM emissions to 1.2 lb/ton of asphalt charged to the blowing stills....
Dynamic Mechanical Characterizations and Road Performances of Flame Retardant Asphalt Mortars and Concretes
Institute of Scientific and Technical Information of China (English)
QIN Xiantao; ZHU Siyue; LI Zuzhong; CHEN Shuanfa
To research the dynamic mechanical properties and road performances of flame retardant asphalt mortars and mixtures, four different asphalt mortars/mixtures were prepared: a reference group and three asphalt mortars/mixtures containing composite lfame retardant materials (M-FRs) of different proportions. Temperature sweep, frequency sweep, repeated creep test, force ductility test and bending beam rheological test were carried out to research the dynamic mechanical properties of asphalt mortars containing M-FRs; wheel-tracking test, low-temperature bending test and freeze-thaw split test were used to study the road performances of asphalt mixtures containing M-FRs. The results show that high-temperature performances of the three lfame retardant asphalt mortars improve greatly, while low-temperature cracking resistances decline. Both high-temperature performances and water stabilities of asphalt mixtures containing M-FRs are quite good and exceed the speciifcation requirements. However, their low-temperature performances decline in different degrees. In summary, besides their good lfame retardancy, the lfame retardant asphalt mortars and mixtures also exhibit acceptable road performance.
Investigation of self healing behaviour of asphalt mixes using beam on elastic foundation setup
Qiu, J.; Molenaar, A.A.A.; Van de Ven, M.F.C.; Wu, S.; Yu, J.
Self healing of asphalt mixes is known for more than four decades. However, it is a complex phenomenon which depends on the duration of the rest period, temperature, crack size, etc. In order to quantify the self healing behaviour of asphalt mixes, a test setup was proposed in this research using an
Directory of Open Access Journals (Sweden)
Renaldo C. Walters
Full Text Available The life expectancy of Asphalt Binder (AB has been negatively impacted by the harsh bombardment of UV rays. UV rays cause asphalt to oxidize faster, which results in deterioration of asphalt rheological characteristics that can lead to pavement distresses. This study investigates the impact of bio-char and nano-clay of asphalt rheological properties. Two nano scale materials were used for this study were nano-clay and bio-char. Nano-clay (Cloisite 30B is a naturally occurring inorganic mineral. Bio-char is the waste product from bio-binder production. Bio-binder is produced from swine manure using a thermochemical conversion process. This process is then followed by a filtration procedure where the bio-char is produced. Chemical and physical properties of bio-char showed a significant presence of carbon which could in turn enhance asphalt flow properties and reduce the rate of asphalt oxidation. In this study several mixtures are designed and evaluated using Rotational Viscometer testing (RV and X-Ray Diffraction (XRD. Nano-clay is blended at 2 and 4% by weight, with and without bio-binder (5% by weight of dry mass. Bio-char is grinded to nano scale and added to the virgin asphalt binder (PG 64-22 at 2, 5 and 10% by weight. The study results showed that introduction of nano-clay could be effective in reducing temperature susceptibility of asphalt binder.
Asphalt Pavement Aging and Temperature Dependent Properties Using Functionally Graded Viscoelastic Model
Dave, Eshan V.
Asphalt concrete pavements are inherently graded viscoelastic structures. Oxidative aging of asphalt binder and temperature cycling due to climatic conditions being the major cause of non-homogeneity. Current pavement analysis and simulation procedures dwell on the use of layered approach to account for these non-homogeneities. The conventional…
Determination of Required Energy Action at Formation of Asphalt Concrete Mixture
B. M. Khroustalev; V. N. Romaniuok
A problem pertaining to determination of the concentrated exergy of the asphalt concrete mixture is considered in the paper. The paper shows the possibility to use the concentrated exergy of the asphalt concrete mixture for qualitative energy evaluation of mixing processes.
75 FR 12988 - National Emission Standards for Hazardous Air Pollutants for Area Sources: Asphalt Processing and...
... the asphalt processing and asphalt roofing manufacturing area source category (74 FR 63236). Following... specified in Executive Order 13132, Federalism (64 FR 43255, August 10, 1999). This action does not..., Consultation and Coordination with Indian Tribal Governments (65 FR 67249, November 9, 2000). This...
Distribution of radionuclides in the process of thermal decontamination of asphalt layers
International Nuclear Information System (INIS)
Autoradiographical analysis was used to investigate the radionuclides distribution in the process of thermal decontamination of asphalt. Cs-137 and Sr-90 were introduced in asphalt to simulate real contamination. It was found that penetration of these radionuclides is very small (about 1 mm). No significant emission of radionuclides was observed in the process of thermal decontamination
Experimental Investigation of the Matching Relationship between Asphalt Particle and Reservoir Pore in Profile Control Process
Directory of Open Access Journals (Sweden)
Chengfeng Ren
Full Text Available Modified sulfonated asphalt particles have a bright application prospect of the profile control of thick reservoirs due to the low cost, extensive sources, and good compatibility with reservoir. Nevertheless, the matching relationship between asphalt particles and reservoir pore has seldom been investigated till now. Oversized particles always block the near-wellbore area, which causes high injection pressures, while undersized particles cannot plug large pores. We designed a core for this experiment which has a high permeability zone in front of it and many pressure measuring points. We could quantitatively assess the matching relationship by measuring the on-way resistance coefficient, residual resistance factor, and relative change of permeability of man-made cores after injecting asphalt. Experimental results indicate that asphalt particles with sizes of 0.02 mm, 0.02–0.06 mm, and 0.08–0.1 mm match with reservoir permeability of 500 mD, 1000 mD, and 2000 mD, respectively. Undersized or oversized particles can reduce the conformance control effect, and the concentration of asphalt particles in the injectant can limit their migration ability. When the concentration of asphalt particles increases to 3000 mg/L, accumulations of asphalt particles can be caused in the formation, in which a scheme with asphalt particles alternative water injection is proposed to avoid the accumulation.
Feasibility of using 100% Recycled Asphalt Pavement mixtures for road construction
Carlson, Russell Edgar, IV
Recycled Asphalt Pavement (RAP) is the largest recycled good in the United States and 80 million tons are recycled yearly, saving taxpayers about $1.5 billion dollars. This paper explores the possibility of utilizing 100% RAP materials in asphalt pavement. Asphalt mixtures are produced at 135°C in a typical asphalt plant. However, at 135°C, not all binder from RAP materials may not become effective for coating aggregates. The main objective of the study is to determine the amount of effective binder available from RAP in the asphalt plant. The 100% RAP mixes have aged binder that can alter mix designs and interaction with virgin binder. In this study, to determine low temperature cracking resistance and fatigue performance, samples were prepared using a 100% RAP mix with no virgin binder and a 100% RAP mix with virgin asphalt binder to achieve the optimum binder content of the mix. Second, to determine the effectiveness of binder from RAP materials, compaction tests were performed by heating RAP materials at various temperatures. It was found that 100% RAP mixes cannot be feasible for field use if additional virgin binder is added to reach the optimum asphalt content. Based on limited test results, the low temperature grade was not within proper limits but the beam fatigue testing results were acceptable. Based on compaction test results, additional heating is needed to increase the effectiveness of asphalt binder from RAP materials.
Damage detection and artificial healing of asphalt concrete after trafficking with a load simulator
Bueno, M.; Arraigada, M.; Partl, M. N.
Artificial healing of asphalt concrete by induction heating requires the addition of electrically conductive and/or magnetic materials into the asphalt mixture. Hence, bitumen can be heated up by an alternating electromagnetic field, decreasing therefore its viscosity and allowing it to flow for closing cracks and recover bonding among the mineral aggregates.
Forming limit of sheet metals based on mixed hardening model
Institute of Scientific and Technical Information of China (English)
WANG HaiBo; WAN Min
The calculation method of forming limit of sheet metals based on M-K instability theory is proposed,and the method is applicable to different yield criterions and hardening models. The forming limit dia-grams of AA5754-O, AA6111-T4 aluminum alloy sheet and DP steel sheet under combined loading paths are obtained based on mixed hardening model with YLD2000-2D yield criterion proposed by Barlat in 2003 and L-C nonlinear kinematic hardening model proposed by Lemaitre and Chaboche. The results show that the forming limit diagram made up of limit strain (FLD-strain) is evidently influenced by the loading path. The forming limit diagram made up of limit stress (FLD-stress) is also influenced by loading path and it is not an only curve, which differs from the conventional view. The degree of the influence of loading path on FLD-atress is related with pre-strain. The larger the pre-strain is, the greater the influence of loading path on FLD-atress will be. The change of FLD-stress is small only when pre-strain is small. In addition, the hardening behavior of the material will influence the path-dependence of FLD-streas: The larger the proportion of kinematic hardening in the whole hard-ening is, namely the more obvious Bauschinger effect of the material, the greater the influence of loading path on FLD-streas will be.
Airborne Exposures to Polycyclic Aromatic Compounds Among Workers in Asphalt Roofing Manufacturing Facilities.
Trumbore, David C; Osborn, Linda V; Johnson, Kathleen A; Fayerweather, William E
We studied exposure of 151 workers to polycyclic aromatic compounds and asphalt emissions during the manufacturing of asphalt roofing products-including 64 workers from 10 asphalt plants producing oxidized, straight-run, cutback, and wax- or polymer-modified asphalts, and 87 workers from 11 roofing plants producing asphalt shingles and granulated roll roofing. The facilities were located throughout the United States and used asphalt from many refiners and crude oils. This article helps fill a gap in exposure data for asphalt roofing manufacturing workers by using a fluorescence technique that targets biologically active 4-6 ring polycyclic aromatic compounds and is strongly correlated with carcinogenic activity in animal studies. Worker exposures to polycyclic aromatic compounds were compared between manufacturing plants, at different temperatures and using different raw materials, and to important external benchmarks. High levels of fine limestone particulate in the plant air during roofing manufacturing increased polycyclic aromatic compound exposure, resulting in the hypothesis that the particulate brought adsorbed polycyclic aromatic compounds to the worker breathing zone. Elevated asphalt temperatures increased exposures during the pouring of asphalt. Co-exposures in these workplaces which act as confounders for both the measurement of total organic matter and fluorescence were detected and their influence discussed. Exposures to polycyclic aromatic compounds in asphalt roofing manufacturing facilities were lower than or similar to those reported in hot-mix paving application studies, and much below those reported in studies of hot application of built-up roofing asphalt. These relatively low exposures in manufacturing are primarily attributed to air emission controls in the facilities, and the relatively moderate temperatures, compared to built-up roofing, used in these facilities for oxidized asphalt. The exposure to polycyclic aromatic compounds was a very
Modeling and Simulation of Flow and Formation Damage of Asphalt-Paved Roads
Directory of Open Access Journals (Sweden)
M. H. Alawi
Full Text Available Porous asphalt is a standard asphalt built on aggregate storage bed which allows water to drain through it and reduces stormwater runoff. However, porosity of the porous asphalt and the storage bed may be effectively reduced due to trapping suspended solids from the water or from the asphalt damage. In this paper, we present mathematical modeling and numerical simulation of flow and damage of porous asphalt-paved roads. A mathematical model to describe the fine-particles transport carried by a two-phase flow in a porous medium is presented. The buoyancy, capillarity, and mixed relative permeabilities correlations to fit with the mixed-wet system are considered. Throughout this investigation, we monitor the changing of the fluids properties such as water saturation and solid properties such as porosity and permeability due to trapping the fine-particles.
Road safety effects of porous asphalt: a systematic review of evaluation studies
DEFF Research Database (Denmark)
Elvik, R.; Greibe, Poul
This paper presents a systematic review of studies that have evaluated the effects on road safety of porous asphalt. Porous asphalt is widely used on motorways in Europe, mainly in order to reduce traffic noise and increase road capacity. A meta-analysis was made of six studies, containing a total...... of eighteen estimates of the effect of porous asphalt on accident rates. No clear effect on road safety of porous asphalt was found. All summary estimates of effect indicated very small changes in accident rates and very few were statistically significant at conventional levels. Studies that have evaluated...... of these changes in risk factors on accident occurrence cannot be predicted. On the whole, the research that has been reported so far regarding road safety effects of porous asphalt is inconclusive. The studies are not of high quality and the findings are inconsistent....
Effects of circulating fluidized bed combustion (CFBC) fly ashes as filler on the performances of asphalt
Energy Technology Data Exchange (ETDEWEB)
Qin Li; Hui Xu; Xiaoru Fu; Chen Chen; Jianping Zhai [Nanjing University, Nanjing (China). State Key Laboratory of Pollution Control and Resource Reuse
This work investigated the potential of utilizing circulating fluidized bed combustion (CFBC) fly ashes (CFAs) as alternative filler, substituting mineral powders (MPs) that are widely used in asphalt concrete. Physico-chemical characteristics of the CFAs and MPs, as well as effects of different mix designs of CFAs and asphalt on asphalt performances were examined, including moisture susceptibility, viscosity, ductility, softening point, penetration, and antiaging performances. The results of the study show that generally the CFAs have greater effects than the MPs on improving the performances of asphalt, and that the specific surface area (SSA), free CaO (f-CaO), morphology, and mineralogical phases of the CFAs are more favorable than those of the MPs respectively, while the alkaline values, hydrophilic coefficients, particle size distributions (PSDs), and water contents of the two fillers are similar. It is suggested that CFAs may be more suitable than MPs for the use as asphalt concrete filler.
Zinc coated sheet steel for press hardening
Ghanbari, Zahra N.
Galvanized steels are of interest to enhance corrosion resistance of press-hardened steels, but concerns related to liquid metal embrittlement have been raised. The objective of this study was to assess the soak time and temperature conditions relevant to the hot-stamping process during which Zn penetration did or did not occur in galvanized 22MnB5 press-hardening steel. A GleebleRTM 3500 was used to heat treat samples using hold times and temperatures similar to those used in industrial hot-stamping. Deformation at both elevated temperature and room temperature were conducted to assess the coating and substrate behavior related to forming (at high temperature) and service (at room temperature). The extent of alloying between the coating and substrate was assessed on undeformed samples heat treated under similar conditions to the deformed samples. The coating transitioned from an α + Gamma1 composition to an α (bcc Fe-Zn) phase with increased soak time. This transition likely corresponded to a decrease in availability of Zn-rich liquid in the coating during elevated temperature deformation. Penetration of Zn into the substrate sheet in the undeformed condition was not observed for any of the processing conditions examined. The number and depth of cracks in the coating and substrate steel was also measured in the hot-ductility samples. The number of cracks appeared to increase, while the depth of cracks appeared to decrease, with increasing soak time and increasing soak temperature. The crack depth appeared to be minimized in the sample soaked at the highest soak temperature (900 °C) for intermediate and extended soak times (300 s or 600 s). Zn penetration into the substrate steel was observed in the hot-ductility samples soaked at each hold temperature for the shortest soak time (10 s) before being deformed at elevated temperature. Reduction of area and elongation measurements showed that the coated sample soaked at the highest temperature and longest soak time
Extracting material response from simple mechanical tests on hardening-softening-hardening viscoplastic solids
Mohan, Nisha
Compliant foams are usually characterized by a wide range of desirable mechanical properties. These properties include viscoelasticity at different temperatures, energy absorption, recoverability under cyclic loading, impact resistance, and thermal, electrical, acoustic and radiation-resistance. Some foams contain nano-sized features and are used in small-scale devices. This implies that the characteristic dimensions of foams span multiple length scales, rendering modeling their mechanical properties difficult. Continuum mechanics-based models capture some salient experimental features like the linear elastic regime, followed by non-linear plateau stress regime. However, they lack mesostructural physical details. This makes them incapable of accurately predicting local peaks in stress and strain distributions, which significantly affect the deformation paths. Atomistic methods are capable of capturing the physical origins of deformation at smaller scales, but suffer from impractical computational intensity. Capturing deformation at the so-called meso-scale, which is capable of describing the phenomenon at a continuum level, but with some physical insights, requires developing new theoretical approaches. A fundamental question that motivates the modeling of foams is `how to extract the intrinsic material response from simple mechanical test data, such as stress vs. strain response?' A 3D model was developed to simulate the mechanical response of foam-type materials. The novelty of this model includes unique features such as the hardening-softening-hardening material response, strain rate-dependence, and plastically compressible solids with plastic non-normality. Suggestive links from atomistic simulations of foams were borrowed to formulate a physically informed hardening material input function. Motivated by a model that qualitatively captured the response of foam-type vertically aligned carbon nanotube (VACNT) pillars under uniaxial compression [2011,"Analysis of
Hanford Permanent Isolation Barrier Program: Asphalt technology data and status report - FY 1994
Energy Technology Data Exchange (ETDEWEB)
Freeman, H.D.; Romine, R.A.; Zacher, A.H.
The asphalt layer within the Hanford Permanent Isolation Barrier (HPIB) is an important component of the overall design. This layer provides a RCRA equivalent backup to the overlying earthen layers in the unlikely event that these layers are not able to reduce the infiltration rate to less than 0.05 cm/yr. There is only limited amount of information on using asphalt for a moisture infiltration barrier over the long times required by the HPIB. Therefore, a number of activities are under way, as part of the Barrier Development Program, to obtain data on the performance of asphalt as a moisture barrier in a buried environment over a 1000-year period. These activities include (1) determining RCRA equivalency, (2) measurement of physical properties, (3) measurement of aging characteristics, and (4) relationship to ancient asphalt analogs. During FY 1994 progress was made on all of these activities. Studies were conducted both in the laboratory and on the prototype barrier constructed over the 216-B-57 crib in the 200 East Area on the Hanford Site. This report presents results obtained from the asphalt technology tasks during FY 1994. Also included are updates to planned activities for asphalt analogs and monitoring the asphalt test pad near the prototype barrier. Measurements of hydraulic conductivity on the HMAC portion of the prototype barrier show that the asphalt layers easily meet the RCRA standard of 1 {times} 10{sup -7} cm/s. In-place measurements using a new field falling head technique show an average of 3.66 {times} 10{sup -8} cm/s, while cores taken from the north end of the prototype and measured in a laboratory setup averaged 1.29 {times} 10{sup -9} cm/s. Measurements made on the fluid applied asphalt membrane (polymer-modified asphalt) show an extremely low permeability of less than 1 {times} 10{sup -11} cm/s.
Hanford Permanent Isolation Barrier Program: Asphalt technology data and status report - FY 1994
International Nuclear Information System (INIS)
The asphalt layer within the Hanford Permanent Isolation Barrier (HPIB) is an important component of the overall design. This layer provides a RCRA equivalent backup to the overlying earthen layers in the unlikely event that these layers are not able to reduce the infiltration rate to less than 0.05 cm/yr. There is only limited amount of information on using asphalt for a moisture infiltration barrier over the long times required by the HPIB. Therefore, a number of activities are under way, as part of the Barrier Development Program, to obtain data on the performance of asphalt as a moisture barrier in a buried environment over a 1000-year period. These activities include (1) determining RCRA equivalency, (2) measurement of physical properties, (3) measurement of aging characteristics, and (4) relationship to ancient asphalt analogs. During FY 1994 progress was made on all of these activities. Studies were conducted both in the laboratory and on the prototype barrier constructed over the 216-B-57 crib in the 200 East Area on the Hanford Site. This report presents results obtained from the asphalt technology tasks during FY 1994. Also included are updates to planned activities for asphalt analogs and monitoring the asphalt test pad near the prototype barrier. Measurements of hydraulic conductivity on the HMAC portion of the prototype barrier show that the asphalt layers easily meet the RCRA standard of 1 x 10-7 cm/s. In-place measurements using a new field falling head technique show an average of 3.66 x 10-8 cm/s, while cores taken from the north end of the prototype and measured in a laboratory setup averaged 1.29 x 10-9 cm/s. Measurements made on the fluid applied asphalt membrane (polymer-modified asphalt) show an extremely low permeability of less than 1 x 10-11 cm/s
Experimental evaluation on high temperature rheological properties of various fiber modified asphalt binders
Institute of Scientific and Technical Information of China (English)
陈筝; 吴少鹏; 朱祖煌; 刘杰胜
High temperature rheological properties of fiber modified asphalt binders and impact of the type and content on such properties were studied.Three types of fiber,including polyester(PET),polyacrylonitrile(PAN) and cellulose(CEL),a control content(0%) and four levels of fiber content(2%,4%,6% and 8% by total asphalt binder mass) were used with asphalt binders.The high temperature rheological properties,consisting of complex modulus(G*) and phase angle δ,were measured using SHRP's dynamic shear rheometer(DSR) between 46-82 ℃.Experimental results indicate that the changes of G* and tan δ of fiber modified asphalt binders with the increase of test temperature tend to slow down,and the temperature susceptibility is improved obviously compared to that of original asphalt binder.Fiber modification results in the increase of rutting parameter(G*/sin δ) at high temperatures,the decrease of temperature susceptibility,and further improved high temperature performance of asphalt binder.An excellent correlation exhibits between fiber content and high temperature performance of asphalt binder.Moreover,fiber type also has different influences on the improvement of G*/sin δ,G*/sin δ of PET and PAN fiber asphalt binders are both higher than that of CEL fiber,but G*/sin δ of CEL fiber is still higher than that of original asphalt.However,there is a critical fiber content when fibers start to interact with each other.Therefore,based on the critical fiber content and economic consideration,the optimum fiber contents for various fiber-modified asphalt binders are obtained.
Comparison of different techniques of laser surface hardening
Directory of Open Access Journals (Sweden)
J. Grum
Full Text Available Purpose: The paper gives a comparison of various techniques of laser surface hardening for various kinds of structural and tool steels, and special maraging steel and hardening of nodular graphite and gray cast irons.Design/methodology/approach: Experimental investigations of laser surface transformation hardening, laser remelting and laser shock processing were performed. Trials of laser hardening were carried out under different conditions, with different modes of laser guidance over the specimen surfaces, and with different degrees of path overlapping. Different kinds of absorbents, were tested, the depths of hardened paths or layers were measured, profiles of hardness and residual stresses were measured, the microstructures formed were analysed, and a micro-chemical analysis was made.Findings: The investigations showed that under different laser-hardening conditions quite different surface-layer properties are obtained. A very strong connection of the chosen energy input, the type of absorbent used, the degree of overlapping, and the mode of laser-beam guidance with the depth of the hardened path or layer, and the through-depth profiles of microhardness and residual stresses of the hardened path or layer was found.Research limitations/implications: He industrial requirements for the achievement of appropriate properties of surface layers, with special regard to the hardened-layer depth, and appropriate variations of microhardness and residual stresses are more and more frequent. The residual-stress profiles should have high compressive stresses at the surface and a small gradient of the residual stresses in the subsurface of the hardened layer. In this way high fatigue resistance of a material can be ensured and occurrence and propagation of cracks prevented. These findings offer engineers new concepts in the improvement of surfaces of machine and tool parts.Practical implications: With the present findings constructors and experts in laser
Effect of Short-Term Aging Process on the Moisture Susceptibility of Asphalt Mixtures and Binders Containing Sasobit Warm Mix Additive
Bo Li; Jinyu Yang; Xiaohui Li; Xiang Liu; Feng Han; Liangying Li
Moisture susceptibility is one of the key issues of warm mix asphalt (WMA). In this research, the moisture susceptibility of asphalt mixtures and binders containing Sasobit warm mix additive was investigated in comparison to that of hot mixture asphalt (HMA) through laboratory aging experiments. The WMA asphalt mixtures were aged in the laboratory at three aging temperatures and times. The moisture susceptibility of the asphalt mixtures was measured through the laboratory immersed Marshall te...
Process design of press hardening with gradient material property influence
Neugebauer, R.; Schieck, F.; Rautenstrauch, A.
Press hardening is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press hardening can achieve significant reductions of sheet thickness at constant strength and is therefore a promising technology for the production of lightweight and energy-efficient automobiles. The manganese-boron steel 22MnB5 have been implemented in sheet press hardening owing to their excellent hot formability, high hardenability, and good temperability even at low cooling rates. However, press-hardened components have shown poor ductility and cracking at relatively small strains. A possible solution to this problem is a selective increase of steel sheet ductility by press hardening process design in areas where the component is required to deform plastically during crash tests. To this end, process designers require information about microstructure and mechanical properties as a function of the wide spectrum of cooling rates and sequences and austenitizing treatment conditions that can be encountered in production environments. In the present work, a Continuous Cooling Transformation (CCT) diagram with corresponding material properties of sheet steel 22MnB5 was determined for a wide spectrum of cooling rates. Heating and cooling programs were conducted in a quenching dilatometer. Motivated by the importance of residual elasticity in crash test performance, this property was measured using a micro-bending test and the results were integrated into the CCT diagrams to complement the hardness testing results. This information is essential for the process design of press hardening of sheet components with gradient material properties.
Assessment of porous asphalt pavement performance: hydraulics and water quality
Briggs, J. F.; Ballestero, T. P.; Roseen, R. M.; Houle, J. J.
The objective of this study is to focus on the water quality treatment and hydraulic performance of a porous asphalt pavement parking lot in Durham, New Hampshire. The site was constructed in October 2004 to assess the suitability of porous asphalt pavement for stormwater management in cold climates. The facility consists of a 4-inch asphalt open-graded friction course layer overlying a high porosity sand and gravel base. This base serves as a storage reservoir in-between storms that can slowly infiltrate groundwater. Details on the design, construction, and cost of the facility will be presented. The porous asphalt pavements is qualitatively monitored for signs of distress, especially those due to cold climate stresses like plowing, sanding, salting, and freeze-thaw cycles. Life cycle predictions are discussed. Surface infiltration rates are measured with a constant head device built specifically to test high infiltration capacity pavements. The test measures infiltration rates in a single 4-inch diameter column temporarily sealed to the pavement at its base. A surface inundation test, as described by Bean, is also conducted as a basis for comparison of results (Bean, 2004). These tests assess infiltration rates soon after installation, throughout the winter, during snowmelt, after a winter of salting, sanding, and plowing, and after vacuuming in the spring. Frost penetration into the subsurface reservoir is monitored with a frost gauge. Hydrologic effects of the system are evaluated. Water levels are monitored in the facility and in surrounding wells with continuously logging pressure transducers. The 6-inch underdrain pipe that conveys excess water in the subsurface reservoir to a riprap pad is also continuously monitored for flow. Since porous asphalt pavement systems infiltrate surface water into the subsurface, it is important to assess whether water quality treatment performance in the subsurface reservoir is adequate. The assumed influent water quality is
Test of Microstructur Permeable Asphalt Pavement Used Domato Stone (Quarsite Dolomite As Course Agregate for Surface Layer of Road Pavement
Directory of Open Access Journals (Sweden)
Firdaus Chairuddin
Full Text Available The experiment works was dividing into two phases, for phase one was developed to investigate the properties of aggregates and straight asphalt qualities. The experiment work for phase two was developed to design the porous asphalt mix. In this phase Japan's method and Binamarga's method was used to define optimum asphalt content. In this phase, has result cantabro loss weight 77.10 for asphalt quality 3% and loss weight 9.70 for asphalt quality 5%. asphalt flow down, air void and density values. The experiment work for phase two was developed to investigate the qualities of porous asphalt. In this phase, wheel tracking machine test was used to investigate the dynamic stability of mixes.
Effect of crumb rubber on asphaltic binder chemistry and rheology
Energy Technology Data Exchange (ETDEWEB)
Lima, Cicero de S.; Tome, Luisa G.A.; Sant' ana, Hosiberto B.; Soares, Jorge B.; Soares, Sandra A. [University Federal of Ceara, Fortaleza, CE (Brazil)
The use of the crumb rubber (CR) from scraps tires to modify asphalt binders (AB) at high temperature can improve significantly the performance grade, but the storage stability can be influenced after the mix of AB and CR or polymer. The major concern of asphalt binder with polymer and CR blends is their lack of stability during prolonged storage at high temperatures. The tendency to phase separation under quiescent conditions appears as an important limitation for the practical use of these blends. After the RTFOT and PAV process, the binder conventional and modified was analyzed in a Fourier Transform Infrared spectrometer (FTIR) for chemical characterization. After aging in RTFOT, the AB presented a larger degradation compared to the CR of RABC and RABC commercial. So, the crumb rubber contributed to the binder stability, acting as an antioxidant in the aging process. The dynamic mechanical properties of CR modify asphalts binder before and after graft has been characterized by use of dynamic shear rheometer (DSR) or advances rheology expanded system (ARES) of Rheometric Scientific. The difference in the viscoelastic parameters between the top and the bottom sections of the tube was measured. It has been found that the added content of CR has great effect on the rheological properties of the AB and its high temperature performance. It also has been confirmed that the RABC sample showed larger storage stability compared to the sample RABC commercial observed with viscoelastic parameters. As a consequence, the use CR and aromatic oil can be considered a suitable alternative for modification of binder in pavement. (author)
Microstructural characterization of the chemomechanical behavior of asphalt in terms of aging and fatigue performance properties
Allen, Robert Grover
The study of asphalt chemo-mechanics requires a basic understanding of the physical properties and chemical composition of asphalt and how these properties are linked to changes in performance induced by chemical modifications. This work uniquely implements the framework of chemo-mechanics by investigating two types of chemical modification processes, natural (oxidative aging) and synthetic (chemical doping) as they relate not only to macro-scale properties of asphalt binder but also to the asphalt microstructure and nanorheology. Furthermore, this study demonstrates the application of atomic force microscopy (AFM) imaging and the extraction of nano-scale engineering properties, i.e. elastic modulus, relaxation modulus, and surface energy, as a method to predict performance related to the fatigue characteristics of asphalt binders by modeling intrinsic material flaws present amongst phase interfaces. It was revealed that oxidative aging induces substantial microstructural changes in asphalt, including variations in phase structure, phase properties, and phase distribution. It has also been shown that certain asphalt chemical parameters have a consistent and measureable effect on the asphalt microstructure that is observed with AFM. In fact, particular phases that emerged via chemical doping revealed a surprising correlation between oxidative aging and the saturates chemical parameter of asphalt in terms of how they explicitly impact durability and performance of asphalt. By implementing a crack initiation model---which requires measureable microstructural characteristics as an input parameter---it was found that microstructural flaws (depending on the extremity) can have a more profound impact on asphalt performance than the properties of the material located between the flaws. It was also discovered by comparing the findings to performance data in the Strategic Highway Research Program's (SHRP's) Materials Reference Library (MRL), that the crack initiation model
Viscoelastic Property Evaluation of Asphalt Cement by Ultrasonic Measurement
International Nuclear Information System (INIS)
This study investigates the method to measure the viscoelastic properties of asphalt cement, one of the viscoelastic materials, using the ultrasound. The wave speed and attenuation were measured from -20 .deg. C to 60 .deg. C at the frequency of 2.25MHz. Then, the storage and loss longitudinal moduli, loss tangent storage and loss longitudinal compliances were found depending on the temperatures based on the linear viscoelastic theory. Stress relaxation, creep, and viscosity were predicted using Maxwell and Voigt-Kelvin viscoelastic models. The validity of superposition principle and shift factor were verified by comparing the present results to the data reported in the literatures
Analysis of moisture susceptibility of different loose coated asphalt mixtures
International Nuclear Information System (INIS)
The durability is one of the significant properties of bituminous paving mixtures. It is shown that moisture damage is one of the primary factors affecting the durability of the mixtures. Moisture damage is basically a combined result of two mechanisms: a) Loss of adhesion between the bitumen and aggregate interface and b) Loss of cohesion in the mixture along with several other factors like the changes in binders, aggregates qualities and something else. The aim of this study is therefore to examine the moisture sensitivity, of different combinations of five different kinds of aggregate quarries/sources and six binder types of different penetration grade and properties, and compare the performance of these combinations between four laboratory tests: Static Immersion Test, Total Water Immersion Test (TWIT) Test, Boiling TWIT Test and Rolling Bottle Test. The tests have been carried out at the Taxila Institute of Transportation Engineering (TITE) to obtain the data for loose coated bituminous paving mixtures. The results show that the combination of Margallah aggregate source and ELVALOY Polymer Modified Bitumen provides best resistance against moisture damage and Rolling Bottle Test is the best test to discriminate between different loose coated Asphalt mixtures, irrespective of time taken by the test. major factors that caused moisture-related problems: adhesive failure, bitumen stripping off the aggregate surface and cohesive failure which is due to the loss of mixture stiffness. Moisture-related problems do not occur without the presence of water and traffic, which provides energy to break the adhesive bonds and cause cohesive failures. Repeated freeze-thaw cycles can also accelerate the distress in the pavement. Since the performance of Asphalt mixtures under the affect of moisture is a very complex issue, various researches have been made to simulate the moisture damage in the past years. Asphalt technologists have carried out many attempts to develop
Construction of an experimental sulfur-extended-asphalt pavement
Dodge, K. S.
The design, placement and collection of initial data from a sulfur extended asphalt (SEA) pavement and a conventional pavement used as a control is documented. The SEA pavement used 30 percent sulfur by total weight of the binder. Mix temperatures, hot bin gradations, and toxic emissions were monitored at the plant and the site throughout placement. Aggregates were collected from the hot bin during production of the control and SEA mixes for use in a Marshall mix design. Cores were extracted from both SEA and control pavements 1 month after placement for laboratory testing. Pavement surface properties were also examined after 1 month of service.
New approach for calculating permanent deformation in asphalt pavement
Institute of Scientific and Technical Information of China (English)
TAN Yi-qiu; CHEN Feng-chen; LIU Hao; SU Xin; DONG Ze-jiao; DONG Yu-ming
A new approach using the Fiber Bragg Grating(FBG)sensor and viscoelastic model to monitor and analyze the internal strain and temperature of asphalt pavement is proposed.Some parameters including peak strain,temperature and loading time were calculated with the application of multi-dimensional sensors group.These parameters were incorporated with viscoelastic model of five units to evaluate the permanent deformation of pavement.An application example was conducted,and the results show that it is feasible to analyze and calculate the permanent deformation of pavement structures with FBG sensors.
Anisotropic hardening model based on non-associated flow rule and combined nonlinear kinematic hardening for sheet materials
Taherizadeh, Aboozar; Green, Daniel E.; Yoon, Jeong W.
A material model for more effective analysis of plastic deformation of sheet materials is presented in this paper. The model is capable of considering the following aspects of plastic deformation behavior of sheet materials: the anisotropy in yielding stresses in different directions by using a quadratic yield function (based on Hill's 1948 model and stress ratios), the anisotropy in work hardening by introducing non-constant flow stress hardening in different directions, the anisotropy in plastic strains in different directions by using a quadratic plastic potential function and non-associated flow rule (based on Hill's 1948 model and plastic strain ratios, r-values), and finally some of the cyclic hardening phenomena such as Bauschinger's effect and transient behavior for reverse loading by using a coupled nonlinear kinematic hardening (so-called Armstrong-Frederick-Chaboche model). Basic fundamentals of the plasticity of the model are presented in a general framework. Then, the model adjustment procedure is derived for the plasticity formulations. Also, a generic numerical stress integration procedure is developed based on backward-Euler method (so-called multi-stage return mapping algorithm). Different aspects of the model are verified for DP600 steel sheet. Results show that the new model is able to predict the sheet material behavior in both anisotropic hardening and cyclic hardening regimes more accurately. By featuring the above-mentioned facts in the presented constitutive model, it is expected that more accurate results can be obtained by implementing this model in computational simulations of sheet material forming processes. For instance, more precise results of springback prediction of the parts formed from highly anisotropic hardened materials or that of determining the forming limit diagrams is highly expected by using the developed material model.
Reduction of work hardening rate in low-carbon steels
Yalamanchili, Bhaskar Rao
Low carbon grades of steel rods are used to produce finished products such as fine wire, coat hangers, staples, and roofing nails. These products are subject to ductility failures during production due to excessively high work hardening rates during wire drawing. The high work hardening rates are attributed to the presence of residuals, free nitrogen, or combinations thereof. This research concludes that the most cost-effective way to reduce the work hardening rate during wire drawing is to combine boron with nitrogen to form boron nitride, and thus reducing its work hardening contribution. The results of this study also conclude the following: (1) Boron/Nitrogen ratio is the more significant factor than rod tensile strength, which affects work hardening rate. Higher ratio is better in the 0.79 to 1.19 range. (2) Maintaining this narrow B/N range requires precise process control. (3) Process conditions such as dissolved oxygen (Steel Texas (North Star) benefited from this research by being able to provide a competitive edge in both quality and cost of its low carbon boron grades thus making North Star a preferred supplier of wire rod for these products.
Cryptographic Path Hardening: Hiding Vulnerabilities in Software through Cryptography
Ganesh, Vijay; Rinard, Martin
We propose a novel approach to improving software security called Cryptographic Path Hardening, which is aimed at hiding security vulnerabilities in software from attackers through the use of provably secure and obfuscated cryptographic devices to harden paths in programs. By "harden" we mean that certain error-checking if-conditionals in a given program P are replaced by equivalent" we mean that adversaries cannot use semi-automatic program analysis techniques to reason about the hardened program paths and thus cannot discover as-yet-unknown errors along those paths, except perhaps through black-box dictionary attacks or random testing (which we can never prevent). Other than these unpreventable attack methods, we can make program analysis aimed at error-finding "provably hard" for a resource-bounded attacker, in the same sense that cryptographic schemes are hard to break. Unlike security-through-obscurity, in Cryptographic Path Hardening we use provably-secure crypto devices to hide errors and our mathemati...
General analytical shakedown solution for structures with kinematic hardening materials
Guo, Baofeng; Zou, Zongyuan; Jin, Miao
The effect of kinematic hardening behavior on the shakedown behaviors of structure has been investigated by performing shakedown analysis for some specific problems. The results obtained only show that the shakedown limit loads of structures with kinematic hardening model are larger than or equal to those with perfectly plastic model of the same initial yield stress. To further investigate the rules governing the different shakedown behaviors of kinematic hardening structures, the extended shakedown theorem for limited kinematic hardening is applied, the shakedown condition is then proposed, and a general analytical solution for the structural shakedown limit load is thus derived. The analytical shakedown limit loads for fully reversed cyclic loading and non-fully reversed cyclic loading are then given based on the general solution. The resulting analytical solution is applied to some specific problems: a hollow specimen subjected to tension and torsion, a flanged pipe subjected to pressure and axial force and a square plate with small central hole subjected to biaxial tension. The results obtained are compared with those in literatures, they are consistent with each other. Based on the resulting general analytical solution, rules governing the general effects of kinematic hardening behavior on the shakedown behavior of structure are clearly.
Research on nonlinear constitutive relationship of permanent deformation in asphalt pavements
Institute of Scientific and Technical Information of China (English)
PENG; Miaojuan; XU; Zhihong
To predict correctly the rut depths in asphalt pavements,a new nonlinear viscoelastic-elastoplastic constitutive model of permanent deformation in asphalt pavements is presented.The model combines a generalized Maxwell model with an elastoplastic one.Then from the creep theory,the linear and nonlinear constitutive equations of the generalized Maxwell model are obtained.From the nonlinear finite element method for the rutting of the asphalt pavement,the rut depths of 4 asphalt-aggregate mixtures are obtained.And the results are compared with the ones from the finite element method by SHRP and the experiments by SWK/UN.The results in this paper are better than the ones by SHRP,and agree with the ones of the experiment by SWK/UN.This shows that the nonlinear viscoelastic-elastoplastic constitutive model,which is presented in this paper for the rutting of the asphalt pavement,is effective.The properties,such as nonlinear elasticity,plasticity,viscoelasticity and nonlinear viscoelasticity,which affect the rutting of an asphalt pavement,can be shown in the model.And the characteristics of the permanent deformation of the asphalt pavement can be presented entirely in the model.
Greenhouse Gas Emissions from Asphalt Pavement Construction: A Case Study in China.
Ma, Feng; Sha, Aimin; Lin, Ruiyu; Huang, Yue; Wang, Chao
In China, the construction of asphalt pavement has a significant impact on the environment, and energy use and greenhouse gas (GHG) emissions from asphalt pavement construction have been receiving increasing attention in recent years. At present, there is no universal criterion for the evaluation of GHG emissions in asphalt pavement construction. This paper proposes to define the system boundaries for GHG emissions from asphalt pavement by using a process-based life cycle assessment method. A method for evaluating GHG emissions from asphalt pavement construction is suggested. The paper reports a case study of GHG emissions from a typical asphalt pavement construction project in China. The results show that the greenhouse gas emissions from the mixture mixing phase are the highest, and account for about 54% of the total amount. The second highest GHG emission phase is the production of raw materials. For GHG emissions of cement stabilized base/subbase, the production of raw materials emits the most, about 98%. The GHG emission for cement production alone is about 92%. The results indicate that any measures to reduce GHG emissions from asphalt pavement construction should be focused on the raw materials manufacturing stage. If the raw materials production phase is excluded, the measures to reduce GHG emissions should be aimed at the mixture mixing phase.
Greenhouse Gas Emissions from Asphalt Pavement Construction: A Case Study in China.
Ma, Feng; Sha, Aimin; Lin, Ruiyu; Huang, Yue; Wang, Chao
In China, the construction of asphalt pavement has a significant impact on the environment, and energy use and greenhouse gas (GHG) emissions from asphalt pavement construction have been receiving increasing attention in recent years. At present, there is no universal criterion for the evaluation of GHG emissions in asphalt pavement construction. This paper proposes to define the system boundaries for GHG emissions from asphalt pavement by using a process-based life cycle assessment method. A method for evaluating GHG emissions from asphalt pavement construction is suggested. The paper reports a case study of GHG emissions from a typical asphalt pavement construction project in China. The results show that the greenhouse gas emissions from the mixture mixing phase are the highest, and account for about 54% of the total amount. The second highest GHG emission phase is the production of raw materials. For GHG emissions of cement stabilized base/subbase, the production of raw materials emits the most, about 98%. The GHG emission for cement production alone is about 92%. The results indicate that any measures to reduce GHG emissions from asphalt pavement construction should be focused on the raw materials manufacturing stage. If the raw materials production phase is excluded, the measures to reduce GHG emissions should be aimed at the mixture mixing phase. PMID:27011196
Development of high stability hot mix asphalt concrete with hybrid binder
Directory of Open Access Journals (Sweden)
Toshiaki Hirato
Full Text Available Cost reduction of public works projects has been desired due to severe financial circumstances. Therefore, asphalt pavement has been requested to extend its life. Semi-flexible pavement or epoxy asphalt pavement, which has high rutting resistance and oil resistance, may be applied to the place where these performances ae demanded. However, special technique is required in manufacturing and construction. In addition, these materials have also raised a problem that they cannot be recycled. Meanwhile, conventional asphalt pavement has several drawbacks. It is vulnerable to rutting caused by traffic load and damage caused by petroleum oils such as gasoline or motor oil. The materials used in asphalt mixtures were studied for improving the durability of asphalt mixture. A high stability asphalt concrete was developed which has equal or superior performance to semi-flexible pavement and epoxy asphalt pavement. In this paper, the process of selecting the substance and the characteristics evaluation of the developed mixtures ae described. Furthermore, an inspection result as well as follow-up survey of the performance of the developed mixtures obtained from trial and actual construction is shown.
Rutting and Fatigue Cracking Resistance of Waste Cooking Oil Modified Trinidad Asphaltic Materials
Directory of Open Access Journals (Sweden)
Rean Maharaj
Full Text Available The influence of waste cooking oil (WCO on the performance characteristics of asphaltic materials indigenous to Trinidad, namely, Trinidad Lake Asphalt (TLA, Trinidad Petroleum Bitumen (TPB, and TLA : TPB (50 : 50 blend, was investigated to deduce the applicability of the WCO as a performance enhancer for the base asphalt. The rheological properties of complex modulus (G∗ and phase angle (δ were measured for modified base asphalt blends containing up to 10% WCO. The results of rheology studies demonstrated that the incremental addition of WCO to the three parent binders resulted in incremental decreases in the rutting resistance (decrease in G∗/sinδ values and increases in the fatigue cracking resistance (decrease in G∗sinδ value. The fatigue cracking resistance and rutting resistance for the TLA : TPB (50 : 50 blends were between those of the blends containing pure TLA and TPB. As operating temperature increased, an increase in the resistance to fatigue cracking and a decrease in the rutting resistance were observed for all of the WCO modified asphaltic blends. This study demonstrated the capability to create customized asphalt-WCO blends to suit special applications and highlights the potential for WCO to be used as an environmentally attractive option for improving the use of Trinidad asphaltic materials.
Use of Hydrogen from Renewable Energy Source for Powering Hot-Mix Asphalt Plant
Directory of Open Access Journals (Sweden)
Kasthurirangan Gopalakrishnan
Full Text Available A significant portion of paved roads and highways are surfaced with Hot-Mix Asphalt. Environmental Life-Cycle Assessment studies have shown that, in the production of Hot-Mix Asphalt pavements, major consumption of energy takes place during asphalt mixing and drying of aggregates, more than what is consumed during the extraction of crude oil and the distillation of bitumen. Currently, natural gas is the primarily source of fossil fuel used to produce 70 to 90 percent of the Hot-Mix Asphalt in the USA, while the remainder of the Hot-Mix Asphalt is produced using oil, propane, waste oil, or other fuels. Energy-related CO2 emissions resulting from the use of fossil fuels in various industry and transportation sectors represent a significant portion of human-made greenhouse gas emissions. This study investigates the technical feasibility of using a hybrid wind energy system as a clean source of energy for operating an entire Hot-Mix Asphalt production facility. Since wind blows intermittently, the extracted wind energy will be stored in the form of hydrogen which is considered a lightweight, compact energy carrier, for later use, thus creating a ready source of electricity for the Hot-Mix Asphalt plant when wind is not present or when electricity demand is high.
Environmental impacts of asphalt mixes with electric arc furnace steel slag.
Milačič, Radmila; Zuliani, Tea; Oblak, Tina; Mladenovič, Ana; Ančar, Janez Šč
Electric arc furnace (EAF) steel slag can be used as an alternative high-quality material in road construction. Although asphalts with slag aggregates have been recognized as environmentally acceptable, there is a lack of data concerning the potential leaching of toxic Cr(VI) due to the highly alkaline media of EAF slag. Leaching of selected water extractable metals from slag indicated elevated concentrations of total chromium and Cr(VI). To estimate the environmental impacts of asphalt mixes with slag, leachability tests based on diffusion were performed using pure water and salt water as leaching agents. Compact and ground asphalt composites with natural aggregates, and asphalt composites in which the natural aggregates were completely replaced by slag were prepared. The concentrations of total chromium and Cr(VI) were determined in leachates over a time period of 6 mo. After 1 and 6 mo, the concentrations of some other metals were also determined in the leachates. The results indicated that chromium in leachates from asphalt composites with the addition of slag was present almost solely in its hexavalent form. However, the concentrations were very low (below 25 μg L) and did not represent an environmental burden. The leaching of other metals from asphalt composites with the addition of slag was negligible. Therefore, the investigated EAF slag can be considered as environmentally safe substitute for natural aggregates in asphalt mixes.
Caltrans use of scrap tires in asphalt rubber products: a comprehensive review
Directory of Open Access Journals (Sweden)
Haiping Zhou
Full Text Available The California Department of Transportation (Caltrans has been using scrap tire rubber in asphalt pavements since the 1970s in chip seals and the 1980s in rubberized hot mix asphalt(RHMA. Both the wet (field blend and dry processes were used in early trials. Caltrans has also used rubber modified binders containing both crumb rubber modifier and polymer modifier that could be manufactured at a refinery facility, a terminal blend wet process. Since the beginning of this century, Caltrans increased the use of scrap tire rubber in paving projects and invested considerable resources in developing technically sound, cost effective, and environmentally friendly strategies for using scrap tire rubber in roadway applications. By the end of year 2010, approximately 31%of all hot mix asphalt (HMA placed by Caltrans was rubberized HMA, roughly 1.2 million tons. Caltrans efforts in using asphalt rubber products were also demonstrated in its research and technology development. These included the construction of two full-scale field experiments, five warranty projects, and an accelerated pavement study using a heavy vehicle simulator. Additionally, terminal blend asphalt rubber and rubberized warm mix asphalts began to be experimented on trial basis. This paper provides a comprehensive review of Caltrans experience over four decades with asphalt rubber products. Current practices and future outlook are also discussed.
The Potential of Heat Collection from Solar Radiation in Asphalt Solar Collectors in Malaysia
Beddu, Salmia; Talib, Siti Hidayah Abdul; Itam, Zarina
The implementation of asphalt solar collectors as a means of an energy source is being widely studied in recent years. Asphalt pavements are exposed to daily solar radiation, and are capable of reaching up to 70°C in temperature. The potential of harvesting energy from solar pavements as an alternative energy source in replace of non-renewable energy sources prone to depletion such as fuel is promising. In Malaysia, the sun intensity is quite high and for this reason, absorbing the heat from sun radiation, and then utilizing it in many other applications such as generating electricity could definitely be impressive. Previous researches on the different methods of studying the effect of heat absorption caused by solar radiation prove to be quite old and inaffective. More recent findings, on the otherhand, prove to be more informative. This paper focuses on determining the potential of heat collection from solar radiation in asphalt solar collectors using steel piping. The asphalt solar collector model constructed for this research was prepared in the civil engineering laboratory. The hot mixed asphalt (HMA) contains 10% bitumen mixed with 90% aggregates of the total size of asphalt. Three stainless steel pipes were embedded into the interior region of the model according to the design criteria, and then put to test. Results show that harvesting energy from asphalt solar collectors proves highly potential in Malaysia due its the hot climate.
Glass Transition and Molecular Mobility in Styrene-Butadiene Rubber Modified Asphalt.
Khabaz, Fardin; Khare, Rajesh
Asphalt, a soft matter consisting of more than a thousand chemical species, is of vital importance for the transportation infrastructure, yet it poses significant challenges for microscopic theory and modeling approaches due to its multicomponent nature. Polymeric additives can potentially enhance the thermo-mechanical properties of asphalt, thus helping reduce the road repair costs; rational design of such systems requires knowledge of the molecular structure and dynamics of these systems. We have used molecular dynamics (MD) simulations to investigate the volumetric, structural, and dynamic properties of the neat asphalt as well as styrene-butadiene rubber (SBR) modified asphalt systems. The volume-temperature behavior of the asphalt systems exhibited a glass transition phenomenon, akin to that observed in experiments. The glass transition temperature, room temperature density, and coefficient of volume thermal expansion of the neat asphalt systems so evaluated were in agreement with experimental data when the effect of the high cooling rate used in simulations was accounted for. While the volumetric properties of SBR modified asphalt were found to be insensitive to the presence of the SBR additive, the addition of SBR led to an increase in the aggregation of asphaltene molecules. Furthermore, addition of SBR caused a reduction in the mobility of the constituent molecules of asphalt, with the reduction being more significant for the larger constituent molecules. Similar to other glass forming liquids, the reciprocal of the diffusion coefficient of the selected molecules was observed to follow the Vogel-Fulcher-Tammann (VFT) behavior as a function of temperature. These results suggest the potential for using polymeric additives for enhancing the dynamic mechanical properties of asphalt without affecting its volumetric properties. PMID:26451630
How to transform an asphalt concrete pavement into a solar turbine
International Nuclear Information System (INIS)
Highlights: • We create a system for harvesting energy from asphalt concrete. • We create an artificial porosity in the asphalt concrete. • We connect a chimney to this porosity. • Differences in temperature produce an air flow. • This air flow serves also for cooling down the pavement. - Abstract: Asphalt concrete can absorb a considerable amount of the incident solar radiation. For this reason asphalt roads could be used as solar collectors. There have been different attempts to achieve this goal. All of them have been done by integrating pipes conducting liquid, through the structure of the asphalt concrete. The problem of this system is that all pipes need to be interconnected: if one is broken, the liquid will come out and damage the asphalt concrete. To overcome these limitations, in this article, an alternative concept is proposed:parallel air conduits, where air can circulate will be integrated in the pavement structure. The idea is to connect these artificial pore volumes in the pavement to an updraft or to a downdraft chimney. Differences of temperature between the pavement and the environment can be used to create an air flow, which would allow wind turbines to produce an amount of energy and that would cool the pavement down in summer or even warm it up in winter. To demonstrate that this is possible, an asphalt concrete prototype has been created and basics calculations on the parameters affecting the system have been done. It has been found that different temperatures, volumes of air inside the asphalt and the difference of temperature between the asphalt concrete and the environment are critical to maximize the air flow through the pavement. Moreover, it has been found that this system can be also used to reduce the heat island effect
A review of changes in composition of hot mix asphalt in the United States.
Mundt, Diane J; Marano, Kristin M; Nunes, Anthony P; Adams, Robert C
This review researched the materials, methods, and practices in the hot mix asphalt industry that might impact future exposure assessments and epidemiologic research on road paving workers. Since World War II, the U.S. interstate highway system, increased traffic volume, transportation speeds, and vehicle axle loads have necessitated an increase in demand for hot mix asphalt for road construction and maintenance, while requiring a consistent road paving product that meets state-specific physical performance specifications. We reviewed typical practices in hot mix asphalt paving in the United States to understand the extent to which materials are and have been added to hot mix asphalt to meet specifications and how changes in practices and technology could affect evaluation of worker exposures for future research. Historical documents were reviewed, and industry experts from 16 states were interviewed to obtain relevant information on industry practices. Participants from all states reported additive use, with most being less than 2% by weight. Crumb rubber and recycled asphalt pavement were added in concentrations approximately 10% per unit weight of the mix. The most frequently added materials included polymers and anti-stripping agents. Crumb rubber, sulfur, asbestos, roofing shingles, slag, or fly ash have been used in limited amounts for short periods of time or in limited geographic areas. No state reported using coal tar as an additive to hot mix asphalt or as a binder alternative in hot mix pavements for high-volume road construction. Coal tar may be present in recycled asphalt pavement from historical use, which would need to be considered in future exposure assessments of pavers. Changes in hot mix asphalt production and laydown emission control equipment have been universally implemented over time as the technology has become available to reduce potential worker exposures. This work is a companion review to a study undertaken in the petroleum refining
Distribution characteristics and petroleum geological significance of the Silurian asphaltic sandstones in Tarim Basin
Institute of Scientific and Technical Information of China (English)
ZHANG; Jun; PANG; Xiongqi; LIU; Luofu; JIANG; Zhenxue; LIU
The Tarim Basin is a typical superimposed basin in which there have occurred multiphase adjustment and destruction of the reservoirs. The widely distributed asphaltic sandstones of the Silurian are the very product after destruction of the reservoirs. Studies show that the Silurian asphaltic sandstones distributed in both the middle and western parts on the basin are controlled chiefly by the Caledonian oil source area and by the Tazhong, Tabei and Bachu uplifts, whereas the distribution of the asphaltic sandstones on local structural belts is controlled by the reservoir's sedimentary system. Vertically, most of the asphaltic sandstones are under the regional caprock of red mudstones and the upper sandstone section of compact lithology. Due to the difference of hydrocarbon destruction in the early stage and the influence of hydrocarbon recharge in the late stage, the asphaltic sandstones and oil-bearing sandstones in the Tazhong area can be vertically divided into the upper and lower sections and they have an interactive distribution relationship as well. Asphaltic sandstones exist not only in intergranular pores but also inside the grains of sand and between the crevices, proving the destruction of early reservoirs due to uplifting. The existence of asphaltic sandstones over a large area reveals that the large-scale migration and accumulation and the subsequent destruction of hydrocarbons in the Craton area. The destruction caused a loss of the reserve resources of the Palaeozoic amounting to nearly 13.3 billion tons. Asphaltic sandstones formed after the destruction of oil and gas may serve as an effective caprock which is beneficial to accumulation of hydrocarbons and formation of the pool sealed by asphaltic sandstones in the later stage. The destruction of the early Silurian hydrocarbons depends on the stratigraphic burial depth. The deep part under the northern slope of Tazhong is an area favorable to search of undestroyed Silurian oil reservoirs.
Engineering design guidelines for electromagnetic pulse hardening of naval equipment
Rogers, S. R.; Perala, R. A.; Rosich, R. K.; Cook, R. B.; Rudolph, T. H.
This document is intended to be used by engineers who design and manufacture shipboard equipment. It is complete in the sense that both the EMP hazard and the means of mitigating the hazard (hardening) are presented. The hazard is described, which not only discusses EMP generation in a general sense, but it also presents specific threat levels for EMP fields and transient currents and voltages included on cables and antennas which are connected to electronic equipment. This specific threat constitutes an EMP survivability criteria which must be met by the mission critical equipment. The necessary hardening technology areas include volume shielding, cable shielding and connectors, interface susceptibility analysis, terminal protective devices, upset and upset hardening, common mode rejection techniques, optical isolation, and grounding/bonding techniques. Test techniques which can verify equipment hardness are presented along with methods to observe the equipment's hardness and maintain the hardness.
Influence of coolant motion on structure of hardened steel element
Directory of Open Access Journals (Sweden)
A. Kulawik
Full Text Available Presented paper is focused on volumetric hardening process using liquid low melting point metal as a coolant. Effect of convective motion of the coolant on material structure after hardening is investigated. Comparison with results obtained for model neglecting motion of liquid is executed. Mathematical and numerical model based on Finite Element Metod is described. Characteristic Based Split (CBS method is used to uncouple velocities and pressure and finally to solve Navier-Stokes equation. Petrov-Galerkin formulation is employed to stabilize convective term in heat transport equation. Phase transformations model is created on the basis of Johnson-Mehl and Avrami laws. Continuous cooling diagram (CTPc for C45 steel is exploited in presented model of phase transformations. Temporary temperatures, phases participation, thermal and structural strains in hardening element and coolant velocities are shown and discussed.
Stress field near an interface edge of linear hardening materials
Institute of Scientific and Technical Information of China (English)
The elastic-plastic singular stress field near an interface edge of bounded linear hardening material is substantially as same as that of bonded elastic materials whose Young's modulus and Poisson ratio are substituted by equivalent values, respectively. Further investigation by the elasto-plastic boundary element method (BEM) on the stress field near the interface edge showed that the stress field there can be divided into three regions: the domain region of the elastic-plastic singular stress field, the transitional region and the elastic region. The domain region of the elastic-plastic singular stress becomes larger with the increasing of the linear hardening coefficient. When the linear hardening coefficient decreases to a certain value, the effective stress in most of the yield zone equals approximately the yield stress. The stress distribution in the elastic region under small-scale yielding condition was also investigated.
Stress field near an interface edge of linear hardening materials
Institute of Scientific and Technical Information of China (English)
许金泉; 付列东
The elastic-plastic singular stress field near an interface edge of bounded linear hardening material is substantially as same as that of bonded elastic materials whose Young' s modulus and Poisson ratio are substituted by equivalent values, respectively. Further investigation by the elasto-plastic boundary element method (BEM) on the stress field near the interface edge showed that the stress field there can be divided into three regions: the domain region of the elastic-plastic singular stress field, the transitional region and the elastic region. The domain region of the elastic-plastic singular stress becomes larger with the increasing of the linear hardening coefficient. When the linear hardening coefficient decreases to a certain value, the effective stress in most of the yield zone equals approximately the yield stress. The stress distribution in the elastic region under small-scale yielding condition was also investigated.
Survival Analysis of Fatigue and Rutting Failures in Asphalt Pavements
Directory of Open Access Journals (Sweden)
Pabitra Rajbongshi
Full Text Available Fatigue and rutting are two primary failure mechanisms in asphalt pavements. The evaluations of fatigue and rutting performances are significantly uncertain due to large uncertainties involved with the traffic and pavement life parameters. Therefore, deterministically it is inadequate to predict when an in-service pavement would fail. Thus, the deterministic failure time which is known as design life (yr of pavement becomes random in nature. Reliability analysis of such time (t dependent random variable is the survival analysis of the structure. This paper presents the survival analysis of fatigue and rutting failures in asphalt pavement structures. It is observed that the survival of pavements with time can be obtained using the bathtub concept that contains a constant failure rate period and an increasing failure rate period. The survival function (S(t, probability density function (pdf, and probability distribution function (PDF of failure time parameter are derived using bathtub analysis. It is seen that the distribution of failure time follows three parametric Weibull distributions. This paper also works out to find the most reliable life (YrR of pavement sections corresponding to any reliability level of survivability.
Waste plastic as a stabilizing additive in Stone Mastic Asphalt
Directory of Open Access Journals (Sweden)
Dr. K.S.Beena
Full Text Available The present study investigates the benefits of stabilizing the stone mastic asphalt (SMA mixture in flexible pavement with shredded waste plastic. Conventional (without plastic and the stabilized SMA mixtures were subjected to performance tests including Marshall Stability, tensile strength and compressive strength tests. Triaxial tests were also conducted with varying percentage bitumen by weight of mineral aggregate (6% to 8% and by varying percentage plasticby weight of mix (6% to 12% with an increment of 1%. Plastic content of 10% by weight of bitumen is recommended for the improvement of the performance of Stone Mastic Asphalt mixtures. 10% plastic contentgives an increase in the stability, split tensile strength and compressive strength of about 64%, 18% and 75% respectively compared to the conventional SMA mix. Triaxial test results show a 44% increase in cohesion and 3% decrease in angle of shearing resistanceshowing an increase in the shear strength. The drain down value decreases with an increase in plastic content and the value is only 0.09 % at 10% plastic content and proves to be an effective stabilizing additive in SMA mixtures.
Asphalt-emulsion sealing of uranium-mill tailings
International Nuclear Information System (INIS)
The use of asphalt emulsion to contain radon and radium in uranium tailings is being investigated at the Pacific Northwest Laboratory. Results of these studies indicate that a radon flux reduction of greater than 99% can be obtained using either a poured-on/sprayed-on seal (3.0 to 7.0 mm thick) or an admix seal (2.5 to 12.7 cm thick) containing about 18 wt % residual asphalt. A field test was carried out at the Grand Junction tailings pile in order to demonstrate the sealing process. A reduction in radon flux ranging from 4.5 to greater than 99% (76% average) was achieved using a 12.7-cm (5-in.) admix seal with a sprayed-on top coat. A hydrostatic stabilizer used to apply the admix was followed by compaction, which formed the radon seal. Overburden was applied to provide a protective soil layer over the seal. Included in part of the overburden was a herbicide to prevent root penetration
Rheological evaluation of polymer-modified asphalt binders
Directory of Open Access Journals (Sweden)
Mônica Romero Santos Fernandes
Full Text Available Currently, the most used polymer for asphalt binder modification is the thermoplastic elastomer styrene butadiene styrene (SBS and aromatic oil is commonly added to the mixtures to improve their compatibly. This paper proposes the use of oil shale from sedimentary rock as a compatibilizer agent for polymer-modified asphalt binder (PMB. PMBs were produced by mixing a bitumen with a linear SBS copolymer (3.5% (w.w-1 using two oil shale contents (2 and 4% and petroleum aromatic oil to evaluate comparatively the effect of the compatibilizer agent on the SBS PMB properties. The rheological characteristics of the SBS PMBs were analyzed in a dynamic shear rheometer (DSR and the morphology accessed by fluorescence optical microscopy. The viscoelastic behavior of the samples corroborated the results for the classical properties and varied according to the sample morphology and composition. The results indicate that the aromatic and shale oils have similar effects on the microstructure, storage stability and viscoelastic behavior of the PMBs. Thus, shale oil could be successfully used as a compatibilizer agent without loss of properties or could even replace the aromatic oil. Following the Superpave methodology it was observed that the linear- and radial-SBS PMBs and linear-SBS PMB with 2% of shale oil can be used up to 70 °C, and the linear-SBS PMBs with 4% of shale oil or 2% of aromatic oil can be used only up to 64 °C.
Numerical Analysis of Asphalt Pavements under Moving Wheel Loads
Institute of Scientific and Technical Information of China (English)
The responses of the pavement in service are the basis for the design of the semi-rigid base course asphalt pavement.Due to the dynamic characteristics of wheel loads and the temperature loads,the dynamic response analysis is very significant.In this article, the dynamic analysis of asphalt pavement under moving wheel loads is carried out using finite element method coupled with non-reflective boundary method.The influences of the base modulus, thickness, the vehicle velocity, the tire pressure, and the contact condition at the interface are studied using parametric analysis.The results of numerical analysis show that it is not appropriate to simply increase the base modulus or thickness in the design.It would be beneficial if the base design is optimized synthetically.The increase of damping is also beneficial to the pavements because of the surface deflection and the stresses declination.Furthermore, the good contact condition at the interface results in good performance because it combines every layer of the pavement to work together.As overload aggravates the working condition of the pavement, it is not allowed.
Development of an asphalt aging procedure to assess long-term binder performance
Juristyarini, Pramitha
Nine asphalts, including seven Strategic Highway Research Program asphalts and two Texas asphalts, were aged at several conditions of temperature and oxygen pressure to develop an aging test. Values for a dynamic shear rheometer function, a combination of both elastic and viscous properties that serves as an indicator of susceptibility to age-related pavement cracking, were measured for both aged and unaged samples. Each aging condition was ranked and calibrated against environmental room aging (60°C, 1 atm air), used to simulate road aging. PAV thin-film aging at 90°C, 20 atm air for 32 hr best represented environmental room aging. © Taylor & Francis Group, LLC.
Sulfur extended asphalt pavement evaluation in the State of Washington: SR 270 highway pavement performance report
Mahoney, J. P.; Terrel, R. L.; Cook, J. C.
The placement and performance of sulfur extended asphalt (SEA) paving mixtures at a highway test site (SR 270) near Pullman, Washington is summarized. The mixture and structural designs and construction details are included. This is followed by a discussion of the data collection and analysis accomplished over a three year evaluation period (1979-1982). A major experimental feature of the study was the use of 0.100 (conventional asphalt concrete), 30/70 and 40/60 SEA binder ratios (sulfur/asphalt ratios are expressed as weight percents in the experimental paving mixtures.
Mechanical analysis of asphalt mixtures produced with waste plastic modified binders
Costa, Liliana M. B.; Fernandes, Sara R. M.; Silva, Hugo Manuel Ribeiro Dias da; Oliveira, Joel; Miranda, Ricardo Filipe Martins
This work compares the viscoelastic properties of an asphalt binder (70/100 pen) modified with different waste plastics and the mechanical properties of the resultant asphalt mixtures. Two different plastic wastes were used, namely recycled HDPE and EVA. Three different polymer modified binders were produced with these plastic wastes: i) 5% HDPE modified binder (P5); ii) 5% EVA modified binder (E5) and; iii) a modified binder with 4% of EVA and 2% HDPE (E4P2). Asphalt mixtures were produced w...
Can oil, plastic and RAP wastes have a new life in novel asphalt mixtures?
Fernandes, Sérgio; Costa, L; Silva, Hugo Manuel Ribeiro Dias da; Oliveira, Joel; Machado, A.V.; F Duarte
The pavement recycling allows to reuse reclaimed asphalt pavement (RAP) or other waste materials in new asphalt mixtures for road construction or rehabilitation, thus re-ducing the use of virgin materials (aggregates and bitumen). Thus, the main aim of this study is to minimize the use of natural resources through the reuse of three waste materials: HDPE, mo-tor oil and RAP. Different amounts of waste motor oil and HDPE were added to an asphalt binder with 50% aged bitumen. The best solutions...
Epoxy asphalt concrete paving on the deck of long-span steel bridges
Institute of Scientific and Technical Information of China (English)
HUANG Wei; QIAN Zhendong; CHEN Gang; YANG Jun
It is the first systematic research in the world on the composition design of epoxy asphalt concrete as pav- ing material. Material characteristics and service perform- ance of mixture, fatigue resistance characteristics of epoxy asphalt concrete by the fatigue test of complex beam have also been described. This research indicates that epoxy asphalt concrete is a good type of paving material. Research results have been applied successfully in the paving of steel deck of the Second Nanjing Yangtze River Bridge (SNYRB). It provides a new paving type for long-span steel bridges of China and has a bright application prospect.
Directory of Open Access Journals (Sweden)
V. A. Verenko
Full Text Available The paper describes a methodology for evaluation of technical and economic efficiency of asphalt concrete mixture components. The method allows to perform a directed search for new materials which are used for mixture preparation and it also provides an efficient use of monetary funds. Firstly, it is possible to obtain this result due to optimum price-quality ratio of asphalt mixture which is determined by its service life in a pavement; secondly, it is possible to obtain this result due to exclusion of errors while selecting components of the asphalt mixture out of the whole range applied presently in the world practice.
Forming limit of sheet metals based on mixed hardening model
Institute of Scientific and Technical Information of China (English)
The calculation method of forming limit of sheet metals based on M-K instability theory is proposed,and the method is applicable to different yield criterions and hardening models.The forming limit dia-grams of AA5754-O,AA6111-T4 aluminum alloy sheet and DP steel sheet under combined loading paths are obtained based on mixed hardening model with YLD2000-2D yield criterion proposed by Barlat in 2003 and L-C nonlinear kinematic hardening model proposed by Lemaitre and Chaboche.The results show that the forming limit diagram made up of limit strain(FLD-strain) is evidently influenced by the loading path.The forming limit diagram made up of limit stress(FLD-stress) is also influenced by loading path and it is not an only curve,which differs from the conventional view.The degree of the influence of loading path on FLD-stress is related with pre-strain.The larger the pre-strain is,the greater the influence of loading path on FLD-stress will be.The change of FLD-stress is small only when pre-strain is small.In addition,the hardening behavior of the material will influence the path-dependence of FLD-stress:The larger the proportion of kinematic hardening in the whole hard-ening is,namely the more obvious Bauschinger effect of the material,the greater the influence of loading path on FLD-stress will be.
Determination of Anisotropic Hardening of Sheet Metals by Shear Tests
Schikorra, Marco; Brosius, Alexander; Kleiner, Matthias
With regard to the increasing necessity of accurate material data determination for the prediction of springback, a material testing equipment has been developed and set up for the measurement of material hardening within cyclic loading. One reason for inaccurate springback predictions can be seen in a missing consideration of load reversal effects in a realistic material model description. Due to bending and unbending while the material is drawn from the flange over a radius of a deep drawing tool, a hardening takes place which leads to an expanding or shifting of the elastic area and yield locus known as isotropic, kinematic, or combined hardening. Since springback is mainly influenced by the actual stress state and a correct distinction between elastic and elastic-plastic regions, an accurate prediction of these stress and strain components is basically required to simulate springback accurately, too. The presented testing method deals with shearing of sheet metal specimens in one or more load cycles to analyze the change of yield point and yield curve. The experimental set up is presented and discussed and the results are shown for different materials such as aluminum A199.5, stainless steel X5CrNi18.10, dual phase steel DP600, and copper Cu99.99. To guarantee a wide experimental range, different sheet thicknesses were used additionally. Simulations using the finite element method were carried out to compare the measured results with calculated results from different yield criterions and different hardening laws mentioned above. It was possible to show that commonly used standard material hardening laws like isotropic and kinematic hardening laws often do not lead to accurate stress state predictions when load reversals occur. The work shows the range of occurring differences and strategies to obtain to a more reliable prediction.
Ballistic Perforation of Surface Hardened Mild Steel Plates
Thorsen, Henrik; Orthe, Erlend
The main objective with this thesis was to investigate experimentally and numerically the effect surface hardening has on the ballistic properties of monolithic and laminated mild steel plates. 300x300 mm^2 plates of thicknesses 12 mm, 6 mm, and 4 mm were made from a low carbon structural steel (NVE36) and combined in such a way that the total thickness always was 12 mm. Some of the plates were then surface hardened by the Kverneland Group to obtain different hardness profiles; (1) as-receive...
Aspect-oriented security hardening of UML design models
Mouheb, Djedjiga; Pourzandi, Makan; Wang, Lingyu; Nouh, Mariam; Ziarati, Raha; Alhadidi, Dima; Talhi, Chamseddine; Lima, Vitor
This book comprehensively presents a novel approach to the systematic security hardening of software design models expressed in the standard UML language. It combines model-driven engineering and the aspect-oriented paradigm to integrate security practices into the early phases of the software development process. To this end, a UML profile has been developed for the specification of security hardening aspects on UML diagrams. In addition, a weaving framework, with the underlying theoretical foundations, has been designed for the systematic injection of security aspects into UML models. The
Temperature influence on water transport in hardened cement pastes
Energy Technology Data Exchange (ETDEWEB)
Drouet, Emeline [CEA, DEN, DPC, SECR, Laboratoire d' Etude du Comportement des Bétons et des Argiles, F-91191 Gif sur Yvette Cedex (France); Poyet, Stéphane, E-mail: firstname.lastname@example.com [CEA, DEN, DPC, SECR, Laboratoire d' Etude du Comportement des Bétons et des Argiles, F-91191 Gif sur Yvette Cedex (France); Torrenti, Jean-Michel [Université Paris-Est, IFSTTAR, Département Matériaux & Structures, 14-52 boulevard Newton, F-77447 Marne la Vallée cedex 2 (France)
Describing water transport in concrete is an important issue for the durability assessment of radioactive waste management reinforced concrete structures. Due to the waste thermal output such structures would be submitted to moderate temperatures (up to 80 °C). We have then studied the influence of temperature on water transport within hardened cement pastes of four different formulations. Using a simplified approach (describing only the permeation of liquid water) we characterized the properties needed to describe water transport (up to 80 °C) using dedicated experiments. For each hardened cement paste the results are presented and discussed.
Microstructure and properties of cast iron after laser surface hardening
Directory of Open Access Journals (Sweden)
Full Text Available Laser surface hardening of cast iron is not trivial due to the material's heterogeneity and coarse-grained microstructure, particularly in massive castings. Despite that, hardening of heavy moulds for automotive industry is in high demand. The present paper summarises the findings collected over several years of study of materials structure and surface properties. Phase transformations in the vicinity of graphite are described using examples from production of body parts in automotive industry. The description relates to formation of martensite and carbide-based phases, which leads to hardness values above 65 HRC and to excellent abrasion resistance.
Laser hardening processing on tool steel SKD61
Institute of Scientific and Technical Information of China (English)
This paper is aimed at overcoming different degree defects of crystalline structure in SKD61 carbide tool steel under quenching in solid phase and liquid phase. The paper studies the micro-structure and properties of laser strengthening SKD61 by using the method of laser hardening on the rein-forcement to improve the wear resistance of SKD61 . The results showed that the laser strengthening meth-od can improve the wear resistance of SKD61 . The study can provide reference for laser hardening metal materials.