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*FM 5-428 Field Manual No. 5-428 HEADQUARTERS DEPARTMENT OF THE ARMY Washington, DC, 18 June 1998
CONCRETE AND MASONRY Table of Contents Part One. Concrete
Page PREFACE ...................................................................................................................................... vi CHAPTER 1. GENERAL............................................................................................................. 1-1 Section I. Basic Consideration ................................................................................................ 1-1 Concrete Composition ........................................................................................................ 1-1 Concrete As a Building Material ......................................................................................... 1-3 Section II. Desirable Concrete Properties............................................................................... 1-4 Plastic Concrete.................................................................................................................. 1-4 Hardened Concrete............................................................................................................. 1-5 CHAPTER 2. CONCRETE COMPONENTS............................................................................... 2-1 Section I. Cements.................................................................................................................. 2-1 Portland Cements ............................................................................................................... 2-1 Section II. Water ..................................................................................................................... 2-4 Purpose............................................................................................................................... 2-4 Impurities............................................................................................................................. 2-4 Section III. Aggregates............................................................................................................ 2-6 Characteristics .................................................................................................................... 2-6 Impurities........................................................................................................................... 2-15 Handling and Storing ........................................................................................................ 2-16 Section IV. Admixtures.......................................................................................................... 2-17 Definition and Purpose...................................................................................................... 2-17 Air-entrained Concrete...................................................................................................... 2-17 CHAPTER 3. PROPORTIONING CONCRETE MIXTURES ...................................................... 3-1 Section I. Method Considerations ........................................................................................... 3-1 Selecting Mix Proportions ................................................................................................... 3-1 Basic Guidelines ................................................................................................................. 3-1 Section II. Trial-Batch Method ................................................................................................ 3-6 Basic Guidelines ................................................................................................................. 3-6 Example Using the Trail-Batch Method .............................................................................. 3-6 Section III. Absolute-Volume Method ..................................................................................... 3-9 Basic Guidelines ................................................................................................................. 3-9 DISTRIBUTION RESTRICTION: Approved for public release; distribution is unlimited. *This publication supersedes FM 5-742, 14 March 1985.
Example Using the Absolute-Volume Method .................................................................. 3-10 Variation in Mixtures ......................................................................................................... 3-13 Adjustments for Moisture on Aggregates.......................................................................... 3-14 Summary........................................................................................................................... 3-19 CHAPTER 4. FORM DESIGN AND CONSTRUCTION ............................................................. 4-1 Section I. Principles ................................................................................................................ 4-1 Importance of Form Design ................................................................................................ 4-1 Form Characteristics........................................................................................................... 4-1 Form Materials .................................................................................................................... 4-2 Forming ............................................................................................................................... 4-3 Section II. Design.................................................................................................................... 4-5 Design Considerations........................................................................................................ 4-6 Basis of Form Design.......................................................................................................... 4-6 Panel-Wall Form Design ..................................................................................................... 4-6 Bracing for Wall Forms ..................................................................................................... 4-18 Overhead Slab Form Design ............................................................................................ 4-22 Concrete Slab on Grade Thickness Design...................................................................... 4-29 Column Form Design ........................................................................................................ 4-35 Section III. Construction........................................................................................................ 4-37 Foundation Forms............................................................................................................. 4-37 Column and Footing Forms .............................................................................................. 4-41 Panel-Wall Forms ............................................................................................................. 4-42 Stair Forms ....................................................................................................................... 4-46 Steel Pavement Forms ..................................................................................................... 4-46 Oiling and Wetting Forms ................................................................................................. 4-47 Safety Precautions............................................................................................................ 4-48 Form Failure...................................................................................................................... 4-48 Section IV. Joints and Anchors ............................................................................................. 4-49 Joints................................................................................................................................. 4-49 Anchor Bolts...................................................................................................................... 4-55 CHAPTER 5 CONSTRUCTION PROCEDURES ....................................................................... 5-1 Section I. Reconnaissance ..................................................................................................... 5-1 Determining Possible Difficulties ........................................................................................ 5-1 Specific Considerations ...................................................................................................... 5-1 Section II. Site Preparation ..................................................................................................... 5-2 Building Approach Roads ................................................................................................... 5-2 Clearing and Draining the Site ............................................................................................ 5-2 Ensuring Adequate Drainage.............................................................................................. 5-2 Locating the Building Site ................................................................................................... 5-2 Stockpiling Construction Materials...................................................................................... 5-2 Locating Batching Plants .................................................................................................... 5-3 Constructing Safety Facilities ............................................................................................. 5-3 Section III. Excavation ............................................................................................................ 5-3 Excavation and Shoring Considerations............................................................................. 5-3 Section IV. Formwork.............................................................................................................. 5-5 Management Aspects ......................................................................................................... 5-5 Time Element...................................................................................................................... 5-5 Section V. Mixing .................................................................................................................... 5-5 Principles ............................................................................................................................ 5-6 Measuring Mix Materials ..................................................................................................... 5-6 Hand Mixing ........................................................................................................................ 5-7 Machine Mixing and Delivery.............................................................................................. 5-8 Section VI. Handling and Transporting ................................................................................. 5-14 Principles .......................................................................................................................... 5-14
Delivery Methods .............................................................................................................. 5-16 Section VII. Placement.......................................................................................................... 5-21 Importance of Proper Procedures..................................................................................... 5-21 Preliminary Preparation .................................................................................................... 5-22 Placing Concrete............................................................................................................... 5-23 Consolidating Concrete..................................................................................................... 5-25 Placing Concrete Underwater ........................................................................................... 5-27 Section VIII. Finishing ........................................................................................................... 5-29 Finishing Operations ......................................................................................................... 5-29 Finishing Pavement .......................................................................................................... 5-33 Cleaning the Surface ........................................................................................................ 5-34 Section IX. Curing ................................................................................................................. 5-34 Importance of Curing to Hydration.................................................................................... 5-34 Curing Methods................................................................................................................. 5-36 Section X. Temperature Effects............................................................................................ 5-39 Hot-Weather Concreting ................................................................................................... 5-39 Cold Weather Concreting.................................................................................................. 5-42 Section XI. Form Removal .................................................................................................... 5-48 Form Stripping .................................................................................................................. 5-48 Form Removal Procedures ............................................................................................... 5-51 Section XII. Repairing ........................................................................................................... 5-51 New Concrete ................................................................................................................... 5-51 Old Concrete ..................................................................................................................... 5-53 CHAPTER 6. REINFORCED-CONCRETE CONSTRUCTION .................................................. 6-1 Section I. Development And Design ....................................................................................... 6-1 Principles and Definitions.................................................................................................... 6-1 Reinforced-Concrete Design............................................................................................... 6-4 Section II. Structural Members ............................................................................................... 6-4 Reinforcement..................................................................................................................... 6-4 Slab and Wall Reinforcement ............................................................................................. 6-8 Section III. REINFORCING STEEL ........................................................................................ 6-8 Grades, Designations, and Methods .................................................................................. 6-9 Placement ......................................................................................................................... 6-16 Section IV. Precast Concrete................................................................................................ 6-19 Definition and Characteristics ........................................................................................... 6-19 Design ............................................................................................................................... 6-22 Prefabricating .................................................................................................................... 6-22 Transportation................................................................................................................... 6-24 Erecting ............................................................................................................................. 6-24 Part Two. Masonry CHAPTER 7. BASIC EQUIPMENT AND COMPONENTS......................................................... 7-1 Section I. Mason's Tools And Equipment ............................................................................... 7-1 Definition ............................................................................................................................. 7-1 Tools ................................................................................................................................... 7-2 Equipment ........................................................................................................................... 7-4 Section II. Mortar..................................................................................................................... 7-6 Desirable Properties ........................................................................................................... 7-6 Mixing Mortar ...................................................................................................................... 7-8 Section III. Scaffolding ............................................................................................................ 7-9 Construction and Safety...................................................................................................... 7-9 Types of Scaffolding ........................................................................................................... 7-9 Materials Tower ................................................................................................................ 7-13 Elevator ............................................................................................................................. 7-15
CHAPTER 8. CONCRETE MASONRY ...................................................................................... 8-1 Section I. Characteristics of Concrete Block........................................................................... 8-1 Nature and Physical Properties .......................................................................................... 8-1 Concrete Block Masonry Unit ............................................................................................. 8-3 Section II. Construction Procedures ....................................................................................... 8-5 Modular Coordination and Planning ................................................................................... 8-5 Walls and Wall Footings ................................................................................................... 8-10 Subsurface Drainage ........................................................................................................ 8-11 Basement Walls ................................................................................................................ 8-11 Floor and Roof Support..................................................................................................... 8-12 Weathertight Concrete Masonry Walls ............................................................................. 8-12 Intersecting Walls.............................................................................................................. 8-25 Lintels................................................................................................................................ 8-29 Sills.................................................................................................................................... 8-29 Patching and Cleaning Block Walls .................................................................................. 8-31 Section III. Rubble................................................................................................................. 8-33 Rubble Stone Masonry ..................................................................................................... 8-33 Random Rubble Masonry Materials ................................................................................. 8-34 Laying Rubble Stone Masonry.......................................................................................... 8-34 CHAPTER 9. BRICK AND TILE MASONRY .............................................................................. 9-1 Section I. Characteristics of Brick ........................................................................................... 9-1 Physical Properties and Classification................................................................................ 9-1 Strength of Brick Masonry................................................................................................... 9-3 Weather Resistance............................................................................................................ 9-4 Fire Resistance ................................................................................................................... 9-4 Abrasion Resistance ........................................................................................................... 9-5 Insulating Qualities of Brick Masonry.................................................................................. 9-5 Section II. Bricklaying Methods............................................................................................... 9-5 Fundamentals ..................................................................................................................... 9-6 Brick Masonry Terms .......................................................................................................... 9-6 Types of Bonds ................................................................................................................... 9-7 Flashing............................................................................................................................... 9-9 Making and Pointing Mortar Joints ................................................................................... 9-10 Mortar Joints ..................................................................................................................... 9-10 Picking and Spreading Mortar .......................................................................................... 9-10 Making Bed and Head Joint.............................................................................................. 9-11 Inserting a Brick in a Wall ................................................................................................. 9-13 Making Cross Joints and Joints Closure........................................................................... 9-14 Cutting Brick...................................................................................................................... 9-16 Finishing Joints ................................................................................................................. 9-17 Section III. Brick Construction............................................................................................... 9-18 Bricklayer's Duties............................................................................................................. 9-18 Bricktender's Duties .......................................................................................................... 9-18 Laying Footings................................................................................................................. 9-18 Laying an 8-inch Common-Bond Brick Wall ..................................................................... 9-19 Laying an 12-inch Common-Bond Brick Wall ................................................................... 9-29 Protecting Work Inside Walls ............................................................................................ 9-31 Using a Trig....................................................................................................................... 9-31 Constructing Window and Door Openings........................................................................ 9-31 Lintels................................................................................................................................ 9-33 Corbeling........................................................................................................................... 9-35 Arches ............................................................................................................................... 9-36 Watertight Walls................................................................................................................ 9-38 Fire-Resistant Brick........................................................................................................... 9-40
Types of Walls .................................................................................................................. 9-41 Manholes .......................................................................................................................... 9-42 Supporting Beams on a Brick Wall ................................................................................... 9-44 Maintaining and Repairing Brick Walls ............................................................................. 9-45 Cleaning New Brick and Removing Stains ....................................................................... 9-45 Cleaning Old Brick ............................................................................................................ 9-46 Flashing............................................................................................................................. 9-48 Freeze Protection During Construction............................................................................. 9-50 Material Quantities Required ............................................................................................ 9-51 Section IV. Reinforced brick masonry................................................................................... 9-52 Applications and Materials ................................................................................................ 9-52 Construction Methods ....................................................................................................... 9-53 Beams and Lintel Construction ......................................................................................... 9-54 Foundation Footings ......................................................................................................... 9-56 Columns and Walls ........................................................................................................... 9-57 Section V. Structural Clay-Tile Masonry ............................................................................... 9-58 Structural Clay Tile............................................................................................................ 9-58 Physical Characteristics of Structural Clay Tile ................................................................ 9-63 Applications....................................................................................................................... 9-64 Mortar Joints ..................................................................................................................... 9-64 Laying an 8-inch Brick Wall with a 4-inch Hollow-Tile Backing ........................................ 9-66 Laying an 8-inch Structural Clay Tile Wall ........................................................................ 9-67 APPENDIX A. CONVERSION TABLE........................................................................................ A-1 APPENDIX B. METHOD OF MAKING SLUMP TEST................................................................ B-1 Apparatus............................................................................................................................ B-1 Test Specimens .................................................................................................................. B-2 Procedure ........................................................................................................................... B-2 Slump Measurement........................................................................................................... B-3 Supplementary Test Procedure .......................................................................................... B-3 APPENDIX C. FIELD TEST FOR MOISTURE DEFORMATION ON SAND..............................C-1 GLOSSARY .................................................................................................................... Glossary-1 Abbreviations and Acronyms .................................................................................. Glossary-1 Symbols .................................................................................................................. Glossary-4 REFERENCE ................................................................................................................Reference-1 Sources Used .......................................................................................................Reference-1 Reading Recommended .......................................................................................Reference-2 AUTHORIZATION........................................................................................................Authorization
vi . and with reinforced concrete and field construction procedures. and structural clay tiles. mixtures. Fort Leonard Wood. and ingredients of concrete.FM 5-428 Preface PREFACE Field Manual (FM) 5-428 is primarily a training guide and reference text for engineer personnel using concrete and masonry materials in field construction. It further explains construction procedures and methods for these masonry units. Part One covers the physical characteristics. design and construction of forms. The proponent of this publication is HQ TRADOC. properties. Send comments and recommendations on Department of Army (DA) Form 2028 (Recommended Changes to Publications and Blank Forms) directly to Commandant. MO 65473-6650. bricks. Appendix A contains an English to metric measurement conversion chart. Unless this publication states otherwise. nouns and promouns do not refer exclusively to men. Part Two addresses the mason's tools and equipment as well as the physical characteristics and properties of concrete blocks. ATTN: ATSE-TD-D. The manual has two parts: Concrete (Part One) and Masonry (Part Two). USAES.
properties. Different amounts of certain materials will effect the desirable properties of workability. and the proportions of ingredients. construction procedures with emphasis on concrete placement. and uniformity of the mix. PORTLAND CEMENT 1-1 . There are numerous advantages and some limitations for using concrete as a building material. A chemical reaction between the portland cement and water--not drying of the mixture--causes concrete to harden to a stone-like condition. Part one covers the physical characteristics. Although there are other kinds of cement. finishing.FM 5-428 Chptr 1 General PART ONE Concrete 1-1. Chapter 1 General 1-2. Hydration gives off heat. nonsegregation. BASIC CONSIDERATION CONCRETE COMPOSITION 1-3. Concrete is produced by mixing a paste of cement and water with various inert materials. durability. and hardness. known as the heat of hydration. Because hydration--not air drying--hardens concrete. concrete is at first a plastic mass molded into nearly any size or shape. the form design and construction principles. This reaction is called hydration. Concrete is the type of construction material most widely used by both military and civilian personnel. Upon hydration of the cement by the water. freshly placed concrete submerged underwater will harden. the word cement in common usage refers to portland cement. held together by a hardened paste made from cement and water. concrete becomes stone-like in strength. SECTION I. The most commonly used inert materials are sand and gravel or crushed stone. When correctly proportioned. and often controlled amounts of entrained air. A chemical process begins as soon as the cement and water are combined. Concrete is a mixture of aggregate. and curing techniques. and ingredients of concrete.
Admixtures are normally classified into accelerators. Reactions between the cement paste and the aggregate can either improve or harm the bond between the two and consequently. Too much water dilutes the cement paste (binder). For example. The aggregate's physical and chemical properties also affect concrete properties. increase strength. iron oxide. or otherwise alter concrete properties. resulting in weak and porous concrete. depending on the characteristics of its ingredients and the proportions of the mix. shape. generally. silica. water should be free from acids. or cement plaster. Aggregate surface texture influences the bond between the aggregate and the cement paste. The elastic properties of the aggregate influence the elastic properties of the concrete and the paste's resistance to shrinkage. In properly mixed concrete. reduce water requirements. the paste surrounds each aggregate particle and fills all spaces between the particles. When cement is mixed with coarse aggregate (CA) of more than 1/4 inch plus fine aggregate (FA) and water. and organic impurities. All aggregate is screened to ensure proper size gradation. For example. more durable and watertight the concrete. the concrete's quality. Inert filler materials (usually sand and stone or gravel) make up between 60 and 80 percent of the volume of normal concrete. WATER 1-5. limestone aggregate requires more water than similar size marble aggregate. workability agents. the less water in the mix. They usually cause a chemical reaction within the concrete. and miscellaneous materials. and grade influence the amount of water required. oils. The concrete should be workable but not too stiff to use. retardants. 1-2 . because concrete differs from other cement-water-aggregate mixtures in the size of its aggregate. the air content ranges up to about 8 percent of the volume. air-entraining agents. the product is concrete. Aggregate is often washed when impurities are found that can retard cement hydration or deteriorate the concrete's quality. and alumina. Portland cement is the most commonly used modern hydraulic cement. the stronger. it is called mortar. Unless tests or experience indicates that a particular water source is satisfactory. These substances are added to the concrete mixture to accelerate or retard the initial set. It was named after the Isle of Portland in the English Channel. color pigments. In air-entrained concrete. Concrete quality varies widely.FM 5-428 Chptr 1 General 1-4. Many admixtures fall into more than one classification. AGGREGATES 1-6. the word hydraulic is the cement's characteristic of holding aggregate together by using water or other low-viscosity fluids. when cement is mixed with water and aggregates passing the number 4 sieve (16 openings per square inch). improve workability. stucco. aggregate size. The basic ratio of cement to water determines the concrete's strength. ADMIXTURES 1-7. Portland cement is a carefully proportioned and specially processed chemical combination of lime. dampproofing and permeability-reducing agents. alkalis. pozzolans. In this case.
In addition. bridges. Certain limitations of concrete cause cracking and other structural weaknesses that detract from the appearance. Other important concrete applications are in road pavements. During setting and hardening. it not only meets structural demands but lends itself readily to architectural treatment. expansion and contraction joints must be provided in many types of concrete structures to prevent failures. Thermal Movements 1-12. Concrete and cement are among the most important construction materials. sewage-treatment plants. watertight. concrete is used for footings. Moisture is applied when the concrete is hard enough so as not to damage the concrete's surface. irrigation canals. columns. ADVANTAGES 1-9. and useful life of concrete structures. Creep 1-14. LIMITATIONS 1-10. It offers surface continuity (absence of joints) and solidity. Drying Shrinkage and Moisture Movements 1-13. To prevent drying shrinkage in newly placed concrete. Concrete is usually locally available worldwide. Concrete deforms gradually (creeps) under load. This deformation does not recover 1-3 . These movements require that control joints be provided at intervals to avoid unsightly cracks. serviceability. Concrete has a great variety of applications. dams. Listed below are some principal limitations and disadvantages of concrete. A great deal of concrete is used in manufacturing masonry units such as concrete blocks and concrete bricks. Concrete shrinks as it dries and as it hardens. all important building elements. and roof units--in short. the heat of hydration raises the concrete temperature and then it gradually cools. Concrete is fireproof. water-diversion structures. and easy to make. girders. Low Tensile Strength 1-11. In buildings. therefore. its surface is kept moist continuously during the curing process. it will bond with other materials. economical. It expands and contracts with wetting and drying. wall slabs. Concrete members subject to tensile stress must be reinforced with steel bars or mesh to prevent cracking and failure. foundations. These temperature changes can cause severe thermal strains and early cracking. beams. hardened concrete expands and contracts with changes in temperature (at roughly the same rate as steel).FM 5-428 Chptr 1 General CONCRETE AS A BUILDING MATERIAL 1-8. and water-distribution pipelines. airport runways.
Plastic Concrete is a concrete in a relatively fluid state that is readily molded by hand. INGREDIENTS 1-16. One characteristic of workability is consistency. DESIRABLE CONCRETE PROPERTIES PLASTIC CONCRETE 1-17. FAs and CAs are measured by loose volume. The unit of measure for concrete is cubic foot (cu ft). whereas water is measured by the gallon. Significant changes in the mix proportions affect plasticity. It is 1-4 . like a lump of modeling clay. Thus. Concrete normally contains soluble compounds that are leached out in varying amounts by water. UNIFORMITY 1-20. which is measured by the slump test (see Appendix B). The uniformity of plastic concrete affects both its economy and strength. Permeability 1-15. For example.FM 5-428 Chptr 1 General completely when the load is removed. NONSEGREGATION 1-19. It is largely determined by the proportions of FAs and CAs added to a given quantity of paste. A very stiff mix has a low slump and is desirable for many uses. Workability is the relative ease or difficulty of placing and consolidating concrete in the form. WORKABILITY 1-18. plastic concrete should not drop (free fall) more than 3 to 5 feet nor be transported over long distances without proper agitation. A plastic mix keeps all the grains of sand and the pieces of gravel or stone encased and held in place (homogeneous). A specific amount of slump is necessary to obtain the workability required by the intended conditions and method of placement. A more fluid mix is necessary when placing concrete around reinforcing steel. although difficult to place in heavily reinforced sections. Even the best quality concrete is not entirely impervious to moisture. Impermeability is particularly important in reinforced concrete--the concrete must prevent water from reaching the steel reinforcement. a standard sack of portland cement weighs 94 pounds and equals 1 loose cubic foot. Desirable properties of plastic concrete are listed below. Concrete is usually referred to by cubic yards (cu yd) SECTION II. Plastic concrete must be homogeneous and carefully handled to keep segregation to a minimum. The degree of plasticity influences the quality and character of the finished product. unless properly constructed joints allow water to enter the mass.
Additional water allows for workability. ice. frost. The watertightness of air-entrained concrete is superior to that of nonair-entrained concrete. The essential properties that it must have are strength. snow. abrasion. and watertightness. 1-5 . WATERTIGHTNESS 1-24. flexure. DURABILITY 1-23. HARDENED CONCRETE 1-21. Each separate batch of concrete must be proportioned and mixed exactly the same to ensure that the total structural mass has uniform structural properties. the concrete's ability to resist the effects of wind. and the chemical reaction of soils or salts are a measure of its durability.FM 5-428 Chptr 1 General determined by how accurate the ingredients are proportioned and mixed according to specifications. Durability should be a strong consideration for concrete structures expected to last longer than five years. A sack of cement requires about 2 1/2 gallons of water for hydration. The concrete's ability to resist a load in compression. As the W/C ratio increases. Thus.5 gallons per sack of cement (W/C = 0. Climate and weather exposure affect durability. or shear is a measure of its strength. STRENGTH 1-22. Concrete strength is largely determined by the ratio of water to cement in the mixture (pounds of water to pounds of cement). The amount of water in economical concrete mixes ranges from 4 gallons minimum to 7 gallons maximum per sack.48) for concrete exposed to fresh water and 5 gallons per sack (W/C = 0. durability. Tests show that the watertightness of a cement paste depends on the W/C ratio and the extent of the chemical-reaction process between the cement and water. but too much water (a high water:cement [W/C] ratio) reduces the concrete's strength. Air-entrained concrete (see paragraph 2-55) has improved freeze-thaw durability.44) for concrete exposed to saltwater. The Corps of Engineers specifications for watertightness limit the maximum amount of water in concrete mixtures to 5. Hardened Concrete is the end product of any concrete design. durability decreases correspondingly.
which are ground to a fine powder. MANUFACTURE 2-3. sand and gravel.000 degrees Fahrenheit [F]) to form hard pellets called clinkers. AMERICAN SOCIETY FOR TESTING AND MATERIAL (ASTM) TYPES 2-4. The raw materials are finely ground. Regardless of the manufacturer. and then heated (calcined) to the fusion temperature (2. modify the workability. portland cement is the standard for the trade. must adhere to specific standards (clean. Type I 2-5. iron ore. organic matter. Type I cement is a general-purpose cement for concrete that does not require any of the special properties of the other types. It reinforces concrete buildings and bridges. but portland cement is the standard for the building trade. and soil-cement 2-1 . reservoirs. tanks. hard. strong. There are various manufacturers for cement. Admixtures used in limited quantities. In general. Portland cement contains lime and clay minerals (such as limestone. nearly all of it will pass through a number 200 sieve (200 meshes to the linear inch or 40.FM 5-428 Chptr 2 Concrete Components Chapter 2 Concrete Components 2-1. CEMENTS PORTLAND CEMENTS 2-2. strength. and durability of the concrete SECTION I. as they make up the majority of the concrete mix. and aluminum. railways. and grading will also affect the concrete's workability.000 openings per square inch). masonry units. acid. sewers. It is used in pavement and sidewalk construction. It is intended for concrete that is not subjected to a sulfate attack or when the heat of hydration will not cause minimum temperature rise. Water for concrete should be clean and free from damaging amounts of oil. any drinking water free from pronounced odors or taste is satisfactory. oyster shells. culverts.600 to 3. Cement is the primary binder used in concrete. carefully proportioned. marl. Aggregates. and durable). silica sand. clay. Because the powder is extremely fine. distribution. or other harmful substances. coquina shells. ASTM specifications cover five types of portland cements in ASTM C150. water pipes. Aggregate size. and shale). alkali.
such as gravity dams. where the temperature rise from the heat of hydration could damage the structure. temperature rise can be a problem when concrete is placed in warm weather. Type IV cement is unusual in that it has a low heat of hydration. such as when the soil or ground water contacting the concrete has a high sulfate content. Type IV 2-8. the high heat of hydration can cause shrinkage cracking. OTHER ASTM CEMENTS 2-10. Type III cement is a high-early-strength cement that produces design strengths at an early age. Its strength also develops at a slower rate than the other types. However. Although richer mixtures of Type I cement can obtain high early strength. Type IV cement is used primarily in very large concrete structures. ASTM specifications cover the following specific types of portland cements: Air-Entraining Portland Cement 2-11. Type V cement will reach its design strength in 60 days. Sulfate resistant cement (Type V) is used mainly where the concrete is subject to severe sulfate action. Use this material cautiously in concrete structures having a minimum dimension of 2 1/2 feet or more. Type III cement permits fast form removal and in cold weather construction. It has a higher heat of hydration and is ground finer than Type I cement. Type II cement will reach its design strength in 45 days. reduces the period of protection against low temperatures.FM 5-428 Chptr 2 Concrete Components mixtures. It usually generates less heat of hydration and at a slower rate than Type I cement. Type I cement will reach its design strength in 28 days and is more available than other types. Type III cement produces it more satisfactorily and more economically. Type II 2-6. respectively. Typical applications are drainage structures where the sulfate concentrations in either the soil or ground waters are higher than normal but not severe. with the addition of small quantities of air-entraining materials interground 2-2 . Type II cement is modified to resist a moderate sulfate attack. It will reach its design strength in 90 days. and IIIA correspond in composition to cement types I. It is intended for applications requiring a minimal rate and a minimal amount of the heat of hydration. IIA. Cement types IA. and III. II. Type V 2-9. usually seven days or less. Type III 2-7. large structures produces only a slight temperature rise in the concrete that moderately affects the heat of hydration.
Cement is shipped by railroad. It contains water-repellent materials that are ground with the portland-cement clinker. well-distributed. Cement types IS and IS-A are used in ordinary concrete construction. Finely divided siliceous aluminous material reacts chemically with slake and lime at an ordinary temperature and in the presence of moisture. pozzolana (containing silica and alumina) is blended with the ground portland-cement clinker. and IP-A. Masonry cements (also called mortar cement) are a typical mixture of portland cement. Cement quantities for large projects may be stated in tons. and water retention. During the manufacturing of cement types P. and completely separate air bubbles. It contains plastic agents that are added to the portland-cement clinker. Types PA and IP-A also contain an air-entraining additive. q Waterproofed portland cement. q Plastic cement. Especially useful for sidewalks. granulated blast-furnace slag is either interground with the portland-cement clinker or blended with the ground portland cement. air-entraining portland cements produce concrete having improved resistance to freeze-thaw action and to scaling caused by snow and ice removal chemicals. Such concrete contains extremely small (as many as 3 billion per cubic yard). During manufacturing. IP. hydrated lime. PA. 2-3 . PACKAGING AND SHIPPING 2-17.FM 5-428 Chptr 2 Concrete Components with the clinker during manufacturing. Portland Blast-Furnace Slag Cement 2-13. plasticity. or in bulk. Masonry Cement 2-15. SPECIAL PORTLAND CEMENTS 2-16. and other materials that improve workability. forms a strong slow-hardening cement. it is commonly used to make plaster and stucco. White Portland Cement 2-12. Portland Pozzolana Cement 2-14. Other special types of portland cement not covered by ASTM specifications include-q Oil-well portland cement. Cement type IS-A contains an air-entraining additive. or barge in standard sacks weighing 94 pounds. It hardens at the high temperatures that prevail in very deep oil wells. White portland cement is a white-finished concrete product used mainly for architectural purposes. truck.
Water has two functions in the concrete mix--it affects hydration and it improves workability. alkalies. and oil. Mixing water should be clean and free from organic materials. cement sometimes does develop lumps that are difficult to break up. Carbonates. In large concentrations. Store-sacked cement in an airtight warehouse or shed. A test must be performed to determine the effect on setting time if the sum of these dissolved salts exceeds 1. Such cement still retains its quality and is usually restored to a free-flowing condition by rolling the sacks on the floor. water containing many sulfates may be drinkable. Hard lumps indicate partial hydration that reduces both the strength and durability of the finished concrete. WATER PURPOSE 2-19. the cement should be tested to determine its quality. these salts can materially reduce concrete strength.FM 5-428 Chptr 2 Concrete Components STORAGE 2-18. Too many impurities in mixing water can affect not only setting time. If no shed is available. Sacks stored outside for long periods should be covered with tarpaulins or other waterproof coverings so that rain cannot reach either the cement or the platforms. Place them close together to reduce air circulation and away from exterior walls. Test batches can also determine if the cement's setting time is badly affected by water impurities. However. SODIUM CHLORIDE AND SODIUM SULFATE 2-4 . ALKALI CARBONATE AND BICARBONATE 2-21. Portland cement retains its quality indefinitely if kept dry. acids. SECTION II.000 parts per million (ppm). place the sacks on raised. you can increase the concrete's cement content to offset the impurities. but can cause surface efflorescence and corrosion of the steel reinforcement. Cement should be free-flowing and free from lumps when used. Stored. This is a slightly hardened condition caused by packing sacks extremely tight or excessively high. However. IMPURITIES 2-20. Rain-soaked platforms can damage the bottom layers of the sacks. Potable water is usually suitable for mixing with cement. sacked cement sometimes develops warehouse pack. In some cases. bicarbonates of sodium. Store bulk cement in weatherproof bins. The effects of certain common water impurities on the quality of plain concrete are described below. wooden platforms. and potassium can either accelerate or retard the set of different cements. Do no use partially hydrated cement in structures where strength is a critical factor. You can use water of unknown quality if concrete cylinders made with it have 7and 28-day strengths equaling at least 90 percent of the control cylinders made with potable water. but it makes a weak paste that leads to concrete deterioration or failure.
acid mine waters can contain large amounts. IRON SALTS 2-24. Water used in concrete that will have aluminum embodiments should not contain large amounts (more than 550 ppm) of chloride ion. OTHER COMMON SALTS 2-23. and other common inorganic acids in concentrations up to 10. Concentrations of sodium hydroxide above 0. and sodium borate can greatly retard both the set and the strength development. the concrete is watertight. sodium arsenate. Salts of manganese.FM 5-428 Chptr 2 Concrete Components 2-22. The acceptance of acid water is based on the concentration of acids (ppm) in the water. Concentrations of these salts up to 500 ppm are acceptable. Iron salts in concentrations up to 40. tin. Up to 35. The risk of corrosion is reduced if the steel has sufficient cover (4 or more inches).000 ppm of salt in seawater are normally suitable for unreinforced concrete. but seawater can corrode the steel in reinforced concrete.000 ppm.000 ppm are acceptable. copper. nor will magnesium sulfate and magnesium chloride in concentrations up to 40. rather than on the hydrogen-ion activity (pH) of the water. MISCELLANEOUS INORGANIC SALTS 2-25. sulfuric.5 percent by weight of cement can 2-5 . Carbonates of calcium and magnesium are seldom concentrated enough to affect the concrete's strength.000 ppm generally have no harmful effect on concrete strength. Sodium iodate. Although natural groundwater usually contains only small amounts of iron. You can offset the degree of strength reduction that occurs by reducing the W/C ratio. Bicarbonates of calcium and magnesium in concentrations up to 400 ppm will not affect strength. Calcium chloride accelerates both hardening and strength gain.000 ppm of sodium chloride are generally tolerable in concrete that will dry in service and have low potential for corrosive reactions. Concentrations of 20. A highly dissolved solid content in a natural water usually results from a high content of sodium chloride or sodium sulfate. ACID WATERS 2-27. and lead can greatly reduce concrete strength and cause large variations in setting time. whereas concentrations of sodium sulfide as small as 100 ppm can be harmful. Both can be tolerated in rather large quantities in the concrete mix. SEAWATER 2-26. ALKALINE WATERS 2-28. zinc. sodium phosphate. and the concrete contains enough entrained air. Hydrochloric.
000 ppm of suspended clay or fine rock particles without adverse effect. Angular particles require more cement paste to 2-6 . very rough-textured or flat and elongated particles require more water to produce workable concrete than do rounded or cubed particles. Test any water that contains unusual solids. Mixing water can contain up to 2. Perform strength tests if the sugar concentration in the water exceeds 500 ppm. Sewage diluted in a good disposal system generally has no significant effect on the concrete's strength. Water containing algae is unsuitable for making concrete. sugar in quantities of about 0. whereas larger amounts (about 0. For example. Pure mineral (petroleum) oil probably affects strength development less than other oils. Their characteristics considerably influence the mix proportions and economy of the concrete. SUGAR 2-31. OILS 2-33.03 to 0. SECTION III.15 percent by weight of cement) usually retard setting time. Less than 4. ALGAE 2-34.25 percent by weight of cement can substantially reduce strength. SAMITORY WASTE WATER 2-30.20 percent by weight of cement) usually accelerate the set. test the concrete for strength. mineral oil in concentrations greater than 2 percent by weight of cement can reduce the concrete's strength by more than 20 percent. AGGREGATES CHARACTERISTICS 2-35. Small amounts of sugar (0. Higher concentrations may adversely affect other concrete properties and should be avoided. Potassium hydroxide in concentrations up to 1.FM 5-428 Chptr 2 Concrete Components reduce concrete strength. However. Aggregates make up 60 to 80 percent of the concrete's volume. SILT OR SUSPENDED PARTICLES 2-32. However.000 ppm of total solids in industrial waste waters generally reduces compressive strength no more than 10 percent.2 percent by weight of cement has little effect on the strength of the concrete that is developed by some cements but can substantially reduce the strength of others. When making concrete with water having a pH greater than 11. INDUSTRIAL WASTE WATERS 2-29.
Importance for workability of fresh concrete economy. silt. humus (decayed plant matter). and soundness.FM 5-428 Chptr 2 Concrete Components coat them. Table 2-1. The most common contaminating materials are dirt. or other organic matter that appears as a coating or as loose. Aggregate characteristics and standard test Characteristics Significance or Importance Use in the index of aggregate quality. strong.chemical C589 . and standard tests for evaluating are given in Table 2-1. making the concrete more expensive. They produce normal-weight concrete (concrete that weighs 135 to 160 pounds per cubic foot). mica. Use in the structures subjected to weathering Use in all types of structures for strength and durability. C136 Maximum percent flat and elongated pieces Maximum and minimum percent passing standard sieves 2-7 . test CAs containing easily crumbled or laminated particles. crushed stone. You can remove many contaminants simply by washing the aggregate. hard. Aggregates should be clean. clay. Aggregate characteristics. salts. The most commonly used aggregates are sand. ASTM Test or Practice Designation C131 Specification Requirement Maximum percent loss* Resistance to abrasion Resistance to freezing and thawing Chemical stability C666 Maximum number of cycles Maximum expansion of mortar bar* Aggregates must be reactive with cement alkalies* C227 .petrographic Particles shape and surface texture Grading Importance for workability of fresh concrete.aggregate prism C295 . Normal-weight aggregates should meet the specifications for concrete aggregates that restrict contaminating substances and provide standards for gradation. and blast-furnace slag. their significance. warehouse floors. fine material.motor bar C289 . loading platforms. However. abrasion resistance. durable. and free from chemicals or coatings of clay or other fine materials that affect the bond of the cement paste. gravel. and pavements.
FM 5-428 Chptr 2 Concrete Components Bulk unit weight Use in mix-design calculations classification Use in mix-design calculations Use in the control of concrete quality C29 Maximum and minimum unit weight (special concrete) Specific gravity C127. PARTICLE SHAPE AND SURFACE TEXTURE 2-39. ABRASION RESISTANCE 2-36. such as in a heavy-duty concrete floor. You can determine the performance of unknown aggregates by subjecting concrete specimens to both freeze-thaw and strength tests. elongated particles require more fine materials (hence more cement) to produce workable concrete than do rounded or cubed particles. Good field service records are generally the best predictor of nonreactive aggregates. C127. If no service record exists and you suspect an aggregate is chemically unstable. AGGREGATE SIZE DISTRIBUTION AND GRADING 2-8 . and pore structure. use the aggregate. cracking the concrete. The resistance to freezing and thawing relates to aggregate porosity. Very sharp. The undesirable result is that this water will expand anyway. absorption. Avoid stones that break up into long sliver pieces or limit them to a maximum of 15 percent in either FAs or CAs. Abrasion resistance is essential when the aggregate is subject to abrasion. CHEMICAL STABILITY 2-38. You can predict aggregate performance during freezing and thawing in two ways: pasted performance and freeze-thaw tests of concrete specimens.CA C128 . If aggregates from the same source have been satisfactory under those conditions in the past.FA C70. C128 Absorption and surface moisture * Aggregates not conforming to specification requirements can be used if either service records or performance test indicate that they produce concrete having the desired properties. rough aggregate particles or flat. In aggregates. The particle shape and surface texture affect the properties of plastic concrete more than those of hardened concrete. FREEZE AND THAW RESISTANCE 2-37. If particles absorb too much water. there will not be enough pore space for the water to expand during freezing. this characteristic means that they do not react unfavorably with cement. and that external sources do not affect them chemically. laboratory tests are necessary.
The number of a FA sieve corresponds to the number of meshes (square openings) to the linear inch that the sieve contains. 3. and 3/8 inch and number 4 for CAs (other sieves can be used for CAs). 50. 30. Figure 2-1 also gives the grade limits for FA and for one designated size of CA. Grading is controlled by the aggregate producer. Any material retained in the number 4 sieve is considered CA. Size-distribution graphs show the percentage of material passing each sieve (see Figure 2-1). 50. the finer the FA sieve.FM 5-428 Chptr 2 Concrete Components 2-40. and 100 sieves. The size of the mesh openings in consecutive sieves is related by a constant ratio. 8. The standard sieves are numbers 4. and any material that passes the number 200 sieve is too fine for concrete. 16. Normal CA consist of gravel or crushed stone. whereas normal FA is sand. Record the individual weights of the materials 2-9 . unworkable mixes. Many FA gradings can have the same fineness modulus. porosity. quarter a sample of at least 500 grams of sand and sieve it through the numbers 4. 16. 1 1/2. Figure 2-1. Prior experience has shown that exclusive use of very fine sands produces uneconomical mixes. With this exception. a CA sieve is designated by the size of one of its mesh openings. The proportioning of the different particle sizes is called grading an aggregate. whereas exclusive use of very coarse sands produces harsh. and shrinkage. economy. and 100 for FAs and 6. The aggregates particle-size distribution is determined by separation with a series of standard sieves. 3/4. the higher the number. The aggregate's size distribution and grading affect the concrete's workability. The finest CA sieve is the same number 4 used as the coarsest FA sieve. To obtain the fineness modulus of a FA (see Table 2-2). The fineness modulus indicates the fineness of a FA but is not the same as its grade. 8. 30. Limits specified in ASTM C33 for FA and one size of CA Fineness Modulus 2-41.
Take care to obtain representative samples. and fine sands are uneconomical.0 40 130 130 250 270 Cumulative 40 170 300 550 820 Cumilative Percentage Retained 4. In leaner mixes or when small-size CA is used. Table 2-3.0 55. The selection of the best FA grading depends on the application. The result is the fineness modulus of the sample. the richness of the mix. Add the cumulative percents and divide by 100.6 to 2. A sand with a fineness modulus falling between 2.59 Fine Sand 2.0 82.3 and 3.FM 5-428 Chptr 2 Concrete Components retained on each sieve and the cumulative retained weights.20 from all test samples taken at that source. Coarse sand is not as workable.80. Table 2-2. a FA grading near the maximum recommended percentage passing each sieve is desirable 2-10 .000 920 _____ _____ 92.10 Coarse Sand FA Grading 2-42. Typical fineness modulus calculation Screen Size Weight Retained.0 NOTE: Fineness modulus = 280/100 = 2.0 17. The fineness modulus of the aggregate taken from one source should not vary more than 0. in Grams Individual Number4 Number 8 Number 16 Number 30 Number 50 Number 100 Pan Total weight 100 80 1.3 to 2.89 Medium Sand 2.9 to 3. FA having either a very high or a very low fineness modulus is not as good a concrete aggregate as medium sand. Fineness modulus ranges for FAs Fineness Modulus Designation 2.0 _____ 280.1 is suitable for concrete (see Table 2-3).0 30. and the maximum size of the CA used.
bundles of bars. the nominal maximum size of the CA should not be larger than 1/5 the narrowest dimension between the sides of forms. the less paste (water and cement) that is required to produce a given quality. however. a wide range of FA grading can be used without much affect on strength. a smooth finish is desired even though CA is visible. and water gain or bleeding. These limitations may be waived if. Honeycomb or voids are usually first observed when the formwork is removed. In no case should the percentage passing a number 200 sieve exceed 5 percent. making it more cohesive. and 3/4 the minimum clear spacing between individual reinforcing bars or wires. In richer mixes. The water required per cubic yard for concrete with a slump of 3 to 4 inches is shown Figure 2-2. The amount of FA passing the number 50 and 100 sieves affects workability. In some instances. and only 3 percent if the structure is exposed to abrasive wear. Field experience shows that the amount of water required per unit volume of concrete for a given consistency and given aggregates is nearly constant.FM 5-428 Chptr 2 Concrete Components for workability. especially in higher-strength ranges. Aggregate grading falling within those limits are generally satisfactory for most concrete. Grading is expressed as the percentage by weight passing through the various standard sieves. the finished-surface texture. Table 2-4 gives the grading requirements for CA. workability and consolidation methods are such that concrete can be placed without honeycomb or voids. or prestressing tendons or ducts. the amount of cement required decreases as the maximum size of CA increases. concrete containing smaller maximum-size aggregate has a higher compressive strength than concrete with larger maximum-size aggregate at the same W/C ratio Table 2-4. Furthermore the amount of water required decreases with increases in the maximum size of the aggregate. regardless of the cement content or relative proportions of W/C. hard-finished concrete floors. and smooth concrete surfaces cast against forms. These minimum amounts of FA give the concrete better workability. 1/3 the depth of slabs. CA Grading 2-43. coarser FA grading is desirable for economy. CA should be graded up to the largest practicable size for the job conditions. The figure demonstrates that for a given W/C ratio. (These are undesirable areas. in the judgment of the engineer.) The larger the maximum size of the CA. the mix proportions will need to vary to produce workable concrete. If the W/C ratio is kept constant and the ratio of FA to CA is chosen correctly. the FA should contain not less than 15 percent material passing the number 50 sieve and at least 3 or 4 percent (but not more than 10 percent) material passing the number 100 sieve. it is more economical to request that the producer adjust his operation to meet the grading requirements. According to the American Concrete Institute (ACI) 318-83. If the variance continues. Grading requirements for coarse aggregate 2-11 . Bleeding is the rise of water to the concrete's surface. For thin walls. and they produce less water gain or bleeding than lower percentages of FA. The grading of CA of a given maximum size can vary over a wide range without much effect on cement and water requirements if the proportion of FA produces concrete having good workability. If CA grading varies too much.
Grading requirements for CA (continued) Size Number 1 Nominal Size (Sieve) With Square Openings 3 1/2 to 1 1/2 inch 3/4 Inches 0 to 5 1/2 Inches 3/8 Inches No 4 Sleves No 8 Sleves No 16 Sleves 2-12 .FM 5-428 Chptr 2 Concrete Components Size Number Nominal Size (Sieve) With Square Openings 3 1/2 to 1 1/2 inch 2 1/2 to 1 1/2 2 to 4 1 1/2 to #4 1 inch to #4 3/4 inch to #4 1/2 inch to #4 3/8 inch to # 8 2 to 1 inch 1 1/2 to 3/4 4 Inches 3 1/3 Inches 90 to 100 3 Inches 2 1/2 Inches 2 Inches 1 1/2 Inches 1 Inch 1 2 357 467 57 67 7 8 3 4 100 25 to 60 100 90 to 100 100 35 to 70 95 to 100 100 0 to 15 0 to 15 35 to 70 90 to 100 100 95 to 100 100 100 90 to 100 100 35 to 70 90 to 100 0 to 15 20 to 55 Table 2-4.
Percentages are by weight.FM 5-428 Chptr 2 Concrete Components 2 357 467 57 67 7 8 3 4 NOTES: 2 1/2 to 1 1/2 inch 2 inch to #4 1 1/2 in to #4 1 inch to #4 3/4 inch to #4 1/2 inch to #4 3/8 inch to #8 2 to 1 inch 1 1/2 to 3/4 inch 0 to 5 10 to 30 35 to 70 25 to 100 90 to 100 100 100 0 to 5 0 to 15 0 to 5 20 to 55 20 to 55 40 to 70 85 to 100 10 to 30 0 to 5 0 to 5 0 to 10 0 to 10 0 to 15 10 to 30 0 to 5 0 to 5 0 to 5 0 to 10 0 to 5 *Specifications for concrete aggregate as described in ASTM-C33. Water requirements for concrete of a given consistency as a function of CA size Gap-Graded Aggregates 2-13 . Amounts are finer than each laboratory sieve or square openings. Figure 2-2.
Air dry. Aggregate contains an excess of moisture on the surface. The four moisture conditions of aggregates are as follows (see Figure 2-3) q q q q Oven dry. The lack of two or more successive sizes can create segregation problems. that is. The internal structure of an aggregate particle is made up of both solid matter and pores or voids that may or may not contain water. but no excess moisture is present on the surface. Certain particle sizes are entirely or mostly absent in gap-graded aggregates. Pores are saturated but surface is dry--neither absorbing water from nor contributing water to the concrete mix.9. BULK UNIT WEIGHT 2-45. SPECIFIC GRAVITY 2-46. This term is used because the volume contains both aggregate and voids of air spaces. ABSORPTION AND SURFACE MOISTURE 2-47. surface dry (SSD) aggregates. Normal-weight aggregates have specific gravities ranging from 2. However.4 to 2. when all pores are filled with water. Surface and pores are bone-dry and fully absorbent. This is the ratio of aggregate weight to the weight of an equal volume of water. Damp or wet. 2-14 . especially in nonair-entrained concrete having slumps greater than 3 inches.FM 5-428 Chptr 2 Concrete Components 2-44. The specific gravities used in concrete calculations are generally for saturated. surface-dry. gap-graded aggregates can produce higher strengths than normal aggregates in concrete mixes having comparable cement contents. Saturated. Clearly. dry aggregate requires more concrete mixing water. Surface is dry but contains some interior moisture and is therefore somewhat absorbent. for a stiff mix. This is the weight of the aggregate that fills a 1-cubic foot container. Both absorption and surface moisture must be known to control the net water content of the concrete and determine correct batch weights.
due to bulking. often not in proportion to the moisture content of the sand. Table 2-5 summarizes the effects of these substances on concrete Table 2-5. silt. Figure 2-4. Variation in fine-aggregate bulking with moisture and aggregate grading IMPURITIES 2-49. Figure 2-4 shows the variation in the amount of bulking with moisture content and grading. coal. lignite. Aggregates can contain such impure substances as organic matter. Moisture conditions of aggregates Bulking 2-48. but. Bulking is the undesirable increase in volume caused by surface moisture holding the particles apart. clay. Impurities in aggregates 2-15 . The amount can be considerable. be very careful when proportioning by volume. actual sand content can vary widely in a batch volume. Too much moisture on the aggregate surfaces also adds to the concrete mixing water. Therefore. Sand is normally delivered in batch quantities in a damp condition. and certain lightweight and soft particles. Bulking occurs when damp FA is handled. especially the excess water in FA.FM 5-428 Chptr 2 Concrete Components Figure 2-3.
Do not allow aggregate to fall freely from the end of a conveyor belt. You must handle and store aggregates to minimize segregation and prevent contamination by impure substances.FM 5-428 Chptr 2 Concrete Components Impure Substances Effects on Concrete Affects setting and hardening time and may cause deterioration Affects bonding and increases water requirement ASTM Test Designation C40 C87 Organic impurities Materials finer than number 200 sieve C117 Affect durability Coal. When you are using batch equipment and storing some aggregate in bins. Aggregate normally stored in stockpiles builds up in layers of uniform thickness. To minimize segregation. lignite. 2-16 . Stockpiles should not be built up in high cones or allowed to run down slopes because this causes segregation. or other and may cause lightweight materials stains and pop outs Soft particles Affects durability Affects workability and durability and may cause pop outs C1213 C232 Friable particles C142 HANDLING AND STORING 2-50. FA remains at the top of the stockpile while heavier aggregate rolls toward the bottom. load the bins by allowing the aggregate to fall vertically over the outlet. Figure 2-5 shows both the correct and incorrect methods of handling and storing aggregates. Chuting the materials at an angle against the side of the bin causes particle segregation. remove aggregates from stockpiles in horizontal layers.
the heat of hydration. water. and can either accelerate or retard setting and hardening. and entrained air. strength. A major advance in concrete technology in recent years is the introduction of tiny disconnected air bubbles into concrete called air entrainment. Admixtures can also reduce segregation. Correct and Incorrect aggregate handling and storage SECTION IV. An admixture is any material other than cement. or wear resistance. 2-17 . watertightness. AIR-ENTRAINED CONCRETE 2-52. When possible. or aggregate that is added to concrete in small quantities--either immediately before or during mixing--to modify such properties as workability. durability. Air-entrained concrete results from using either an air-entraining cement or an air-entraining admixture during mixing. Similar results are obtainable by changing the concrete-mix proportions instead of using admixtures (except air-entraining ones).FM 5-428 Chptr 2 Concrete Components Figure 2-5. examine all alternatives before using an admixture to determine which is more economical or convenient. ADMIXTURES DEFINITION AND PURPOSE 2-51.
Entrained air improves concrete's resistance to sulfate. the strength varies inversely with the W/C ratio. such as resistance to freezing and thawing in a saturated environment. entrained air bubbles serve as reservoirs for the expanded water. and 2-18 . q Watertightness. q Abrasion resistance. PROPERTIES 2-53. Air-entrained concrete is more watertight than nonair-entrained concrete since entrained air prevents interconnected capillary channels from forming. use air-entrained concrete where watertightness is a requirement. q Freeze-thaw durability. Concrete made with a low W/C ratio. However. q Deicers resistance. q Sulfate resistance. particularly in lean mixes and in mixes containing angular and poorly graded aggregates. increase the amount of cement. The improved workability of air-entrained concrete greatly reduces water and sand requirements. Therefore.FM 5-428 Chptr 2 Concrete Components Adding entrained air to concrete provides important benefits in both plastic and hardened concrete. and cement having a low tricalcium-aluminate content is the most resistant to sulfate attack. such as when slumps remain constant while the concrete's temperature rises when using certain aggregates. In addition. Abrasion resistance increases as the compressive strength increases. animal or vegetable fats or oils. The following are properties of air-entrained concrete: q Workability. Air-entraining admixtures are usually liquid derivatives of natural wood resins. When the air content remains constant. Air entrapped in nonair-entrained concrete fills relatively large voids that are not uniformly distributed throughout the mix. AIR-ENTRAINING MATERIALS 2-54. The expansion of water as it freezes in concrete can create enough pressure to rupture the concrete. q Strength. alkali salts of sulfated or sulfonated organic compounds. For this ratio. it is sometimes difficult to attain high strength with air-entrained concrete. thereby relieving expansion pressure and preventing concrete damage. the disconnected air bubbles reduce segregation and bleeding of plastic concrete. Because entrained air prevents scaling caused by deicing chemicals used for snow and ice removal. reduce the amount of mixing water. you can generally maintain a given strength by holding the voids to the cement ratio constant. Air-entrained concrete has about the same abrasion resistance as that of nonair-entrained concrete of the same compressive strength. voids are defined as the total volume of water plus air (both entrained and entrapped). air-entrained concrete is recommended for all applications where the concrete contacts deicing chemicals. Any strength reduction that accompanies air entrainment is minimized because air-entrained concrete has lower W/C ratios than nonair-entrained concrete having the same slump. As the air content increases. The voids to cement ratio basically determines air-entrained concrete strength. To do this. However. entrained air. or both.
the air content increases sharply as the aggregate size decreases due to the increase in cement volume. As cement content increases. q FA content. q Premature finishing operations.FM 5-428 Chptr 2 Concrete Components water-soluble soaps intended for use in the mixing water. This can cause excess water to work itself to the concrete surface. the air content decreases but remains within the normal range of the cement content. This is the most important factor in producing air-entrained concrete. q Mixing action. Factors affecting air content are: q Aggregate gradation and cement content. Both significantly affect the air content of both air-entrained and nonair-entrained concrete. q Slump and vibration. q Concrete temperature. To prevent a chemical reaction with certain air-entraining admixtures. The amount of entrained air varies with the mixer type and condition. The manufacturer provides instructions to produce a specified air content. Stationary and transit mixers may produce concrete having very different amounts of entrained air. Increasing the FA content incorporates more air in a given amount of air-entraining cement or admixture. the amount of concrete mixed. whereas overloading can decrease air content. At all slumps. RECOMMENDED AIR CONTENT 2-55. Air is incorporated in concrete by using air-entraining cement. 2-19 . properly applied vibration mainly eliminates large air bubbles and little of the intentionally entrained tiny. Air-entraining cements should meet the specifications in ASTM C175. Some manufacturers market automatic dispensers that accurately control the quantities of air-entraining agents in a mix. the larger the percentage reduction in air content during vibration. the surface zone may not contain enough entrained air and be susceptible to scaling. particularly fly ash having high percentages of carbon. Air content produced by air-entraining admixtures meeting ASTM requirements will give about 9 percent air in the fraction of the concrete mixture passing the 4. that is. air bubbles. Add commercial air-entraining admixtures at the mixer. q Admixtures and coloring agents. They should comply with ASTM C260. more air is entrained as the mixing speed increases. Such concrete must be used when there is a danger of concrete freezing while saturated or nearly saturated with water. These affect the air content of air-entrained concrete because the greater the slump. you must add calcium-chloride solutions to the mix separately. and the mixing rate. Less air is entrained as the concrete's temperature increases. or both methods. even a 15-second vibration causes reduced air content. Its effects become more pronounced as slump increases. Generally. For aggregate sizes smaller than 1 1/2 inch. Air contents for frost-resistant concrete must be as stated in Table 2-6.75 millimeter (mm) number 4 sieve. an air-entraining admixture at the mixer. Mixers not loaded to capacity can increase air content. This affects the percentage of entrained air in concrete. Use adequate controls to always ensure the proper air content. These can reduce the amount of entrained air. However. If this occurs. the mortar fraction.
q Volumetric method. in Inches* 3/8 1/2 3/4 1 2** 2** Air Content. This indicates the adequacy of the air-void system when using air-entraining materials meeting ASTM specifications. This method is practical for field testing all concrete except those containing highly porous and lightweight aggregates. Tests should be made regularly during construction. Tolerance on air content as delivered applies to this value. not air-void characteristics. It is 2-20 . When testing concrete aggregates larger than 1 1/2 inch. The following are the standard methods to determine the air content of plastic concrete. q Gravimetric method. Total air content for frost-resistant concrete Nominal Maximum Aggregate Size. in Percentage Severe Exposure 7 1/2 7 6 6 5 4 1/2 Moderate Exposure 6 5 1/2 5 4 1/2 4 3 1/2 *See ATSM C33 for tolerance on oversize of various nominal maximum size designations.FM 5-428 Chptr 2 Concrete Components Table 2-6. Air content of the total mixture is computed from values determined on the minus 1 1/2 fraction. removal is by hand or sieve. particularly concrete containing lightweight and porous aggregates. TESTS FOR AIR CONTENT 2-56. This method is practical for field testing concrete. Tests that determine air entrainment in freshly mixed concrete measure only air volume. ** The air content applies to the total mix. q Pressure method. using plastic samples taken immediately after discharge from the mixer and from already placed and consolidated concrete. Air content is determined on the minus 1 1/2 fraction of the mix. Impractical for field testing because it requires accurate knowledge of specific gravities and absolute volumes of concrete ingredients.
They also offset the accelerating effect of hot weather on the set. fly ash and natural pozzolans should conform to ASTM C618. Add in solution form as part of the mixing water. q Pozzolans. These reduce the quantity of mixing water required to produce concrete of a given consistency. and finely divided materials. in permanent contact with galvanized steel. subject to alkali-aggregate reaction. The slump is increased for a given water content. These materials contain considerable silica or much silica and alumina. the concrete or grout decreases in volume in an amount equal to or greater than that of normal concrete or grout. q Retarding admixtures. However. Calcium chloride is the most common. These are various air-entraining admixtures.06 2-21 . or exposed to soils or water containing sulfates. while hardening. These hasten the set and strength development. q Dampproofing and permeability-reducing agents. When added in small qualities. q Grouting agents. q Accelerating admixtures. but don't exceed 2 percent by weight of cement. These are sometimes used to reduce the rate of hydration to permit placing and consolidating concrete before the initial set. These admixtures generally consist of fatty acids. sugars. When added to concrete or grout in very small quantities. Table 2-7 shows the limitations. Maximum chloride ion content for corrosion protection Type of Members Prestressed concrete Maximum Water Soluble (Chloride Ion in Concrete)* 0. OTHER ADMIXTURES 2-57. The following are admixtures that modify concrete: q Water-reducing admixtures. q Gas-forming agents. and starches. Pozzolans should be tested first to determine their suitability.FM 5-428 Chptr 2 Concrete Components satisfactory for laboratory use. admixtures change the uniformity of the concrete. Table 2-7. retarders. They include entrained air. certain organic materials. accelerators. These are water-repellent materials that are used to reduce the capillary flow of moisture through concrete that contacts water or damp earth. They are combined with calcium hydroxide to form compounds having cement-like properties. Pozzolans are also permeability-reducing agents. Do not use calcium chloride or other admixtures containing soluble chlorides in prestressed concrete or concrete containing embedded aluminum. q Workability agents. When used as workability agents. they cause a slight expansion before hardening in certain applications. and workability agents that alter the properties of portland cement grouts for specific applications. because the properties of pozzolans and their effects on concrete vary considerably. These improve the workability of fresh concrete.
30 2-22 .15 1.00 0.FM 5-428 Chptr 2 Concrete Components Reinforced concrete exposed to chloride in service Reinforced concrete that will be dry or protected from moisture in service Other reinforced concrete construction *Percentages are by weight of cement 0.
durability. and strength. Find a moderate balance between reasonable economy and the requirements for placeability. Use Table 3-1 to select a suitable W/C ratio for normal-weight concrete that will meet the anticipated exposure conditions. but a tentative mix proportion can be determined from knowledge of a prior job. 3-1 . The W/C ratios in Table 3-1 are based on concrete's strength under certain exposure conditions. Always remember that a change in the W/C ratio changes the characteristics of the hardened concrete. Proportions of ingredients for concrete should be selected to make the most economical use of available materials that will produce concrete of the required plausibility. W/C RATIO 3-4. Factors affecting this include-q W/C ratio. durability.FM 5-428 Chptr 3 Proportioning Concrete Mixtures Chapter 3 Proportioning Concrete Mixtures 3-1. certain information about a job is necessary. q Type and size of aggregate. and appearance that may be in the job specifications. If possible. the amount of entrained air. and the slump. durability and watertightness are usually specified by the structural-design engineer. SECTION I. q Air or nonair-entrained concrete. Recommended and typical mixes of concrete for various types or classes of work will determine how you should proportion your concrete mix. q Slump of the mix. perform tests using job materials to determine the relationship between the W/C ratio selected and the strength of the finished concrete. Basic relationships already established and the laboratory tests provide guidance for optimum combinations. the concrete strength required. density. strength. Before proportioning a concrete mixture. aggregate characteristics. durability. and the exposure conditions. BASIC GUIDELINES 3-3. The two primary methods used to proportion a mix design are the trial-batch method and the absolute-volume method. METHOD CONSIDERATIONS SELECTING MIX PROPORTIONS 3-2. Concrete proportions for a particular application are determined by the concrete's end use and by anticipated conditions at the time of placement. such as the size and shape of the structural members. The W/C ratio is determined by the strength. and watertightness requirements of the hardened concrete. Other important factors discussed below are the W/C ratio. Strength.
Table 3-2. frost-resistant concrete and exposure to sulfates. and finishing needs 0. use the lower of the two indicated W/C ratios.FM 5-428 Chptr 3 Proportioning Concrete Mixtures If laboratory-test data is not obtainable or experience records for the relationship are unavailable. * For the properties of watertight concrete. interpolate between the values.50 0.50 0.500 0. If possible. such as a pavement. If flexural strength rather than compressive strength is the basis for a design. When both exposure conditions and strength must be considered. use the data in Table 3-2 as a guide. any section with less than a 2-inch cover over reinforcement and any concrete exposed to deicing salts q All other structures Exposure to sulfates* q Moderate q Severe Concrete placed underwater Floors on grade Normal-Weight Concrete (Absolute W/C Ratio by Weight) Select a W/C ratio on the basis of strength. Maximum permissible W/C ratios for concrete Specified Maximum Absolute Permissible Compressive W/C Ratios by Water Strength. plus minimum cement requirements described in Table 3-7.45 0.67 0.45 Do not use less than 650 pounds of cement per cubic yard (386 kg/m3). An approximate relationship between flexural and compressive strength is as follows: Table 3-1. Select W/C ratio for strength. workability.50 0.45 0.54 3-2 . use designing strength for air-entrained concrete. locate the desired compressive strength of concrete in pounds per square inch (psi) and read across to determine the maximum W/C ratio. perform the necessary tests to determine the relationship between the W/C ratio and flexural strength. In Table 3-2. Maximum W/C ratios for various exposure conditions Exposure Condition Concrete protected from exposure to freezing and thawing or the application of deicer chemicals Watertight concrete* q In freshwater q In seawater Frost-resistant concrete* q Thin sections. in Nonair-Entrained Air-Entrained psi* Concrete Concrete 2.
in psi K = a constant. ENTRAINED AIR 3-3 .FM 5-428 Chptr 3 Proportioning Concrete Mixtures 3.35 ** ** *28-day strength. proportions should be established by the trial-batch method.58 0.500 5. usually between 8 and 10 AGGREGATE 3-5. 3-6. Use FA to fill the spaces between the CA particles and to increase the workability of the mix. the maximum size of aggregate should not exceed one-third the slab thickness. Use the largest practical size of CA in the mix. the less paste (water.40 0. thus. The maximum size of aggregate should not exceed one-fifth the minimum dimension of the member or three-fourths the space between reinforcing bars.500 psi (nonair-entrained concrete) and 4. The larger the maximum size of the CA.000 3.000 psi = 7 MPa.000 psi (air-entrained concrete).000 NOTE: 1. The W/C ratios will provide average strengths that are greater than the specified strengths.38 ** 0.000 4. cement and usually entrained air) that is required for a given concrete quality. Fineness modulus and FA grading are discussed in paragraphs 2-41 and 2-42 .46 0. in most cases. a decrease will take place in the overall cost.51 0. in psi R = flexural strength (modulus of rupture). **For strength above 4. Where-f'c = compressive strength.44 0. For pavement or floor slabs. The maximum size of CA that produces concrete of maximum strength for a given cement content depends upon the aggregate source as well as the aggregate shape and grading. 0.500 4. Aggregate that does not have a large grading gap nor an excess of any size but gives a smooth grading curve produces the best mix.
air entrainment increases slump. less water is required. to mild conditions.5 4. The resulting decrease in the W/C ratio helps to offset possible strength decreases and improves other paste properties.0 5. and percent for air-entrained concrete based exposure levels Table 3-3.0 2.0 3.5 0. The upper half of Table 3-3 gives the percentage of entrapped air in concrete.0 3-4 .2 Recommended percentage average and total air content for air-entrained concrete Anticipated Usage Mild exposure Moderate exposure Severe exposure 4. Approximate mixing-water and air content requirements for different slumps and maximum sizes of aggregate.0 4. regardless of climatic conditions.0 4.5 6.0 7.5 2 1. Maximum Aggregate Size: _____ 3/8 1/2 3/4 1 1 1/2 2** 3** 6** Inch Inch Inch Inch Inches Inches Inches Inches Water in Pounds Per Cubic Yard of Concrete* Slump. sometimes. use entrained air in all concrete that is exposed to freezing and thawing and.5 4.5 7. The lower half of the table gives the recommended average. To improve workability.0 3.5 6.0 6. in Inches 1 to 2 3 to 4 6 to 7 350 385 410 335 365 385 Nonair-Entrained Concrete 315 340 360 300 325 340 275 300 315 260 285 300 240 285 285 210 230 Air-Entrained Concrete 1 to 2 3 to 4 6 to 7 305 340 365 295 325 345 280 305 325 270 295 310 250 275 290 240 265 280 225 250 270 200 220 - Approximate percentage amount of entrapped air in nonair-entrained concrete 3 2.3 0. that of nonair-entrained concrete when cement contents and slumps are the same.5 5. total air content. The strength of air-entrained concrete may equal.5 3.FM 5-428 Chptr 3 Proportioning Concrete Mixtures 3-7. such as permeability.5 2.5 5. or nearly equal.5 4. Table 3-3 gives the recommended total air contents of air-entrained concrete.5 1.0 5. Always use entrained air in paving concrete.0 1. When mixing water remains constant.0 3.5 1 0.0 4. When the cement content and slump remain constant.
When testing different batches of the same mixture. Severe exposure means service where the concrete is exposed to deicing chemicals or other aggressive agents or where the concrete continually contacts moisture or free-standing water before freezing. **The slump values for concrete containing aggregate larger than 1 1/2 inches are based on slump tests made after removal of particles larger than 1 1/2 inches by wet screening. Moderate exposure means service in a climate where freezing is expected. curbs. but where the concrete is not continually exposed to moisture or free-standing water for long periods before freezing or to deicing agents or other aggressive chemicals. or exterior water tanks or slumps.FM 5-428 Chptr 3 Proportioning Concrete Mixtures *These quantities of mixing water are for use in computing cement factors for trial batches. walls. Table 3-4 gives the recommended slump ranges. SLUMP 3-11. Mild Exposure includes indoor or outdoor service in a climate that does not expose the concrete to freezing or deicing agents. The slump test (see Appendix B) measures the consistency of concrete in cubic yards. Slumps for various types of construction (with vibration) Concrete Construction Slump. girders. mix proportions. such as to improve workability or cohesion or to improve strength in low-cement-factor concrete. caissons. Structures that do not contact wet soil or receive direct applications of deicing salts are exterior beams. in Inches Maximum* Minimum* Reinforced foundation walls and footings Plain footing. changes in slump indicate changes in materials. They are maximums for reasonably well-shaped. angular CA graded within limits of accepted specifications. Examples are pavements. sidewalks. you can use air contents that are lower than those required for durability. columns. canal linings. gutters. or water content. Do not use it to compare mixes having different proportions or mixes containing different sizes of aggregate. Severe Exposure 3-10. When you want air entrainment for any reason other than durability. and substructure walls Beams and reinforced walls Building columns Pavements and slabs Mass concrete 3 3 4 4 3 2 1 1 1 1 1 1 3-5 . Mild Exposure 3-8. Moderate Exposure 3-9. bridge decks. and slabs. Table 3-4.
Since the maximum size of the CA must not exceed one-fifth the minimum wall thickness nor three-fourths of the space between the reinforcement and the surfaces. When the concrete quality is specified in terms of the W/C ratio. Calculate the larger quantities per sack and/or per cubic yard. The following steps are setup guidelines: Step 1.000 psi.5 percent. select a W/C ratio of 0.2 pounds 3-6 . cement. This simplifies calculations and eliminates error caused by variations in aggregate moisture content. Table 3-1 indicates that a maximum W/C ratio of 0. Because of the severe exposure conditions. The size of the trial batch depends on the equipment you have and how many test specimens you make. TRIAL-BATCH METHOD BASIC GUIDELINES 3-12. with 2 inches of concrete covering the reinforcement. Be sure to use representative samples of aggregate. Batches using 10 to 20 pounds of cement may be big enough. Table 3-4 indicates a recommended slump ranging from 1 to 3 inches. In the trial-batch method of mix design. The trial-batch proportions are now determined. Pre-wet the aggregate and allow it to dry to a saturated. the trial-batch procedure consists of combining paste with the proper amounts of FA and CA to produce the required slump and workability. although larger batches produce more accurate data. surface-dry condition.46. For a batch containing 20 pounds of cement. assuming that vibration will consolidate the concrete. The required compressive strength is 3.000 psi at 28 days. the mixing water required is: 20 x 0. The trial-batch method determines the mix proportions for a concrete retaining wall exposed to freshwater in a severe climate. EXAMPLE USING THE TRIAL-BATCH METHOD 3-13. Using Type IA (air-entraining) portland cement and a compressive strength of 3. SECTION II. Use machine mixing. the concrete should contain entrained air.50 by weight satisfies the exposure requirements.0. The minimum wall thickness is 8 inches. because representation is close to the actual job conditions.FM 5-428 Chptr 3 Proportioning Concrete Mixtures NOTE: 1 inch = 25 mm *May be increased 1 inch for consolidation by methods such as rods and spades. and air-entraining admixture in the trial batch.46 = 9. Place the aggregate in covered containers to maintain this condition until ready for use. the maximum size of the CA you will choose is 1 1/2 inch. water. Enter all trial-mix data in the appropriate blanks on the trial-mix-data work sheets (see Figure 3-1). Table 3-3 shows that the recommended air content is 5. Step 2. Always use a machine to mix concrete containing entrained air. Table 3-2 shows that a maximum W/C ratio of approximately 0. To meet both specifications.5 +/.46 by weight satisfies the strength requirements. Step 3. use actual job materials to obtain mix proportions. if possible.
FM 5-428 Chptr 3 Proportioning Concrete Mixtures 3-7 .
105 . Determine and note the slump. q q The percentage of FA by weight and by volume of the total aggregate. Work sheet for concrete trial-mix data Step 1. NOTE: It is not normal practice to buy air-entraining cement (Type IA) and then add an air-entraining admixture. Calculate and record-q The cement factor in pounds per cubic yard as indicated in Figure 3-1 . the final quantities for the mix proportions per cubic yard are as follows: Cement Water (538 x 0. and record their weights in column 2 of Figure 3-1. Step 6. by making more trial batches. Figure 3-2 plots the percentage of FA used in these mixes against the cement factor. Step 3. The minimum cement factor (538 pounds per cubic yard) occurs at a FA content of about 32 percent of total aggregate.FM 5-428 Chptr 3 Proportioning Concrete Mixtures Figure 3-1.890 pounds = 3. Find the most economical proportions.46 by weight and the unit weight of the concrete for an air content of 5 percent is about 144 pounds per cubic foot.994) = 994 pounds = 2. Record the results in columns 5 and 6. Step 4. Table 3-5 summarizes the results of four such trial batches made in the laboratory. if the only cement available was Type IA and it did not give the needed air content.105) CA (3.890 . and slump approximately the same. water. The yield of concrete in cubic feet per bag.105 pounds NOTE: 1 cubic yard equals 27 cubic feet FA (0. Add FA and CA until you produce a workable mixture having the proper slump. keep the W/C ratio. air content.46 Total Concrete per cubic yard (144 x 785) Aggregates (3. Record the weights of all materials in column 4 of Figure 3-1. varying the percentage of FA. and unit weight of the concrete. In each batch. Step 2. Since the W/C ratio is 0. Select and weigh representative samples of FA and CA. Calculate the weights for both a 1-bag batch and 1 cubic yard. air content. Step 5.785) = 538 pounds = 247 pounds = 785 pounds = 3. Step 7. air-entraining admixture.111 pounds 3-8 .32 x 3. aggregate gradations. and. workability. However. Use all the measured quantities of cement. 3-14. an addition of an air-entraining admixture would be necessary to achieve frost resistance.
4 4. For this procedure. This method was detailed in ACI 211. air content. select the W/C ratio.FM 5-428 Chptr 3 Proportioning Concrete Mixtures Table 3-5.5 30.9 5. Cement Factor. Concrete mixtures can be proportioned using absolute volumes.4 33. and the maximum size of 3-9 . Air-Content Unit Weight.46 by weight.7 144 144 144 145 540 556 549 540 33. Relationship between percentage of FA and cement content for a given W/C ratio and slump SECTION III. FA* Workability Number in Inches Percentage in Pounds in Pounds Per Cubic Per Cubic feet Yard 1 2 3 4 3 2 3/4 2 1/2 3 1/4 5. ABSOLUTE-VOLUME METHOD BASIC GUIDELINES 3-15.1-81. Results of laboratory trial mixes Batch Slump. slump.5 27.1 4.5 Excellent Harsh Excellent Good NOTE: The W/C ratio selected was 0. *Percentage of total aggregate Figure 3-2.
6 12.000 psi.2 21.70.7 20.1 19. q Maximum size aggregate is 3/4 inch.4 20. cement. Addition information is required before making calculations such as the specific gravities of the FA and CA.5 21.8 16.0 15.1 13.4 14. as described in Method of Test for Unit Weight of Aggregate (ASTM C29). subtract the sum of the absolute volumes of these materials in cubic feet from 27 cubic feet per cubic yard to give the specific volume of the FA. q Fineness modulus of the FA is 2. For less workable concrete.15. From Table 3-6. When placement is to be by pump.6 18. Table 3-6.0 21.5 NOTE: Volumes are based on aggregates in a dry-rodded condition. EXAMPLE USING THE ABSOLUTE-VOLUME METHOD 3-16.5 15.40 2.7 18. such as that required for concrete pavement construction. Then estimate the water requirement using Table 3-3.1 11.9 17.8 19.FM 5-428 Chptr 3 Proportioning Concrete Mixtures the aggregate. in Cubic Feet Per Cubic Yard 13. and the fineness modulus of the FA. These volumes are selected from empirical relationships to produce concrete with a degree of workability suitable for usual reinforced construction.80 3.3 18.6 19. and the dry-rodded unit weight of the CA. in Inches 3/8 1/2 3/4 1 1 1/2 2 3 Fineness Modulus of FA 2. the volume may be increased about 10 percent. volume should be decreased about 10 percent. estimate the volume of dry-rodded CA per cubic yard. the dry-rodded unit weight (DRUW) of the CA.00 CA.2 20. For a retaining wall. q Exposure condition will be moderate freeze-thaw exposure (exposed to air). If the maximum size of the aggregate and the fineness modulus of the FA are known.9 14.3 16. determine the mix proportions using the following specifications and conditions: q Required 28-day compressive strength of 3.2 17. calculate the quantities per cubic yard of water. Finally.1 22. 3-10 . q Specific gravity of portland cement is 3.60 2.6 19.2 20. and air. CA.4 17. Volume of CA per cubic yard of concrete Maximum Size of Aggregate.
W/C = 0. Determine the W/C ratio.50 Watertightness (refer to Table 3-1) is determined by-. and watertightness using the following information: q Strength is determined by-. DRUW of the FA is 103 lb/cu ft.W/C ratio (refer to Table 3-2) = 0.Frost-resistant concrete. durability. Cement type is IA.W/C = 0. Estimate the mixing-water content refer to Table 3-3) using the following information: q q q q Slump = 3 inches Aggregate size = 3/4 inch Air-entrained concrete Mixing water = 305 lb/cu yd Step 3.Freshwater exposure . . .66.Design strength. Step 1. Slump is 3 inches. Check the W/C ratios for strength. Calculate the CA content (refer to Table 3-6) by referring to the following information: q CA size = 3/4 inch 3-11 .61.W/C = 0.46 q Step 4. .Specified compressive strength.46 q Durability (refer to Table 3-1) is determined by-. Calculate cement content (C) using the formula below: Step 5.FM 5-428 Chptr 3 Proportioning Concrete Mixtures q q q q q q Specific gravity of the FA (SGFA) is 2. Specific gravity of the CA (SGCA) is 2.Mix design strength = 3. Dry-rodded unit weight (DRUW) of the CA is 104 lb/cu ft.All other structures . Estimate the air content (refer to Table 3-3) using the following information: q q q q Aggregate size = 3/4 inch Air-entrained concrete Moderate exposure Air content = 5 percent Step 2.000 psi .Selection of the lowest W/C ratio .50 .
cement.7 (given) Determine volume of CA by interpolation by referring to the following information: q Weight of CA.37 cu ft/cu yd Water = 4.47 cu ft/cu yd (PV is the sun of water.35 cu ft/cu yd Partial volume (PV) = 20.89 cu ft/cu yd CA = 10.47 cu ft/cu yd = 6.768 lb/cu yd Where-G = the weight of the CA in lbs / cu yd Step 6. Calculate the FA content by the absolute method using the following formula: q q q q q q q q Summary Cement = 3.FM 5-428 Chptr 3 Proportioning Concrete Mixtures q q Fineness modulus of FA = 2.4 lbs / cu ft = 3-12 .PV 27 cu ft . G = Volume of CA x unit weight of CA G = 17 x 104 lb/cu ft G = 1.20.53 cu ft/cu yd q Weight of FA = absolute vol of FA x SGFA x 62.86 cu ft/cu yd Air = 1. CA and air) Absolute volume of FA = 27 cu ft/cu yd .
the final proportions will vary slightly. such as for concrete used in slabs or other flatwork.in Inches Per Cubic Yard 1 1/2 1 3/4 1/2 3/8 NOTES: 1.66 x 62. mix more trial batches to obtain the desired slump and air content while keeping the W/C ratio constant.9 lbs / cu yd Step 7. For variations in a mixture. The variation is due to the empirical nature of the methods and does not necessarily imply that one method is better than another. there are minimum cement requirements. Determine the proportions for the first trial batch (for 1 cubic yard) by converting the absolute volumes to dry volumes.53 cu ft / cu yd x 2. in Pounds Aggregate.FM 5-428 Chptr 3 Proportioning Concrete Mixtures 6.083.4 lbs / cu ft = 1. depending on the maximum size of the aggregates (see Table 3-7) Table 3-7. The mixture proportions will vary somewhat depending on the method used. Since the methods begin differently and use different procedures. 100 lb/cu yd = 60 kg/m3 470 520 540 590 610 3-13 . VARIATION IN MIXTURES 3-17. Concrete Used in flatwork MaximumSize of Cement. 1 inch = 25 mm 2. Determine the first trial batch. This is to be expected and further points out the necessity of trial mixtures in determining the final mixture proportions. If needed.
Usually. threrfore no adjustment is necessary. The formula for volume increase is as follows: Vwet = Vdry x (1 + BF) Where-V = volume BF = bulking factor (CAs do not bulk. Determine the approximate FSM of the FA by the squeeze test (Appendix C). This factor becomes very important if the concrete is being batched at a mixer by volume (the initial mix design must then be adjusted). you must increase the volume of the FA by the bulking factor (BF) determined from Figure 3-3. their condition must be monitored and appropriate adjustments made as required. that is. therefore.) 3-14 . This is a laboratory condition and seldom occurs in the field. FA have a tendency to bulk (expand in volume) when wetted and when the mass is disturbed. The initial mix design assumes that the aggregates are SSD. q If you are batching your concrete mix by weight. This will yield the weight of the FSM on the aggregates.FM 5-428 Chptr 3 Proportioning Concrete Mixtures ADJUSTMENTS FOR MOISTURE ON AGGREGATES 3-18. neither the FAs nor the CAs have any free water on the surface that would be available as mixing water. Multiply the percentages of FSM on the aggregates by their respective weights per cubic yards. the moisture content of the aggregates will change over a short period of time. Step 3. CAs are free-draining and rarely hold more than 2 percent (by weight) FSM even after heavy rains. Step 2. Divide the total weight of the FSM by 8. Subtract those gallons from the water requirements in the original mix design.33 pounds per gallon to determine the number of gallons of water. A good field test for estimating the free surface moisture (FSM) on FA is contained in Appendix C. 2 percent FSM is the maximum amount that gravel will hold without actually dripping. q If you are batching your concrete by volume. Furthermore. The procedure for adjusting the mixing water and sand bulking due to FSM is as follows: Step 1. you need to account for the weight contributed by the FSM by increasing the total weights of the aggregates per cubic yard by the weights of the FSM. Step 4. The actual amount of water on the sand and gravel can only be determined from the material at the mixing site. Estimate the FSM of the CA by observation.
FM 5-428 Chptr 3 Proportioning Concrete Mixtures Figure 3-3. Bulking factor curves SAMPLE PROBLEM FOR MOISTURE ADJUSTMENT ON AGGREGATES 3-19. adjust the design mix to account for 6 percent FSM on the FA (fineness modulus equals 2.6 gal 3-15 .7) and 2 percent FSM on the CA. Using the final mix proportions as determined in paragraph 3-15. The original mix design was-q Cement = 7.05 sacks (Type IA) q Water = 36.
The increase in FA volume is then-Vwet = Vdry x (1 + BF) = 10. The FA is considered a medium sand.803.083 lb/cu yd x 0.6 gallons minus 12 gallons equals 24. read up to the appropriate sand curve and then read the correct BF on the left edge. Determine the amount of water (in gallons) on the aggregate. Therefore. 36.5 cu ft x (1 + . after periods of dryness.38 lb/cu yd of water FA = 1.38 lb/cu yd = 1.148 lb/cu yd q Air content = 5% It is important to check the moisture content of the aggregates and make appropriate adjustments as conditions change. such as after rains.5 cu ft or 1. For this example. Adjust the volume of the FA to reflect the BF. and after the arrival of new materials. After designing the mix.98 lb/cu yd = 1. Adjust the weights of the aggregates by the amount contributed by the water.98 lb/cu yd of water Total weight of water = 100. use the following steps to estimate the total amounts of materials needed for the job: 3-16 .803.44 cu ft or 1.3 lb/cu yd FA = 1.44 cu ft Step 5.769 lb/cu yd + 35.70. the fineness modulus equals 2. The adjusted mix design to account for the actual field conditions is now-q Cement = 7. then read left to the BF of 0. Select the appropriate moisture content across the bottom of the figure.083 lb/cu yd + 64. This quality-control step assures that the desired concrete is produced throughout the construction phase. FSM equals 6 percent.6 gallons of water that must be added to the mix.768 lb/cu yd x 0.05 sacks (Type IA) q Water = 24. Step 3.FM 5-428 Chptr 3 Proportioning Concrete Mixtures q q q CA = 17.083 lb/cu yd Air content = 5% Step 1. CA = 1.02 = 35. CA = 1. Reduce the original amount of mixing water by the amount contributed by the aggregates as determined in step 1.36 lb/cu yd Convert to gallons: Step 2. From Figure 3-3.0 cu ft or 1.28.06 = 64.768 lb/cu yd FA = 10.0 cu ft or 1.6 gal q CA = 17. read up the figure until it intersects the medium sand line.148 lb/cu yd Step 4. MATERIALS ESTIMATION 3-20.28) = 13.3 lb/cu yd q FA = 13.
and 1 foot wide on the other. Determine the total volume (in cubic yards) of concrete to be placed. If the total volume is 200 cubic yards or less.083 lb/cu yd q Air content = 5% q Step 1. Then convert the answer to tons and round up to the next whole number. The 1 cubic yard mix design is recapped below. Determine the extra amount that will be added for waste. Determine the total amounts of cement. add 5 percent. the wall portion and the footing. FA. 3-17 . by multiplying the amounts of these components needed for 1 cubic yard by the adjusted total volume. Using the mix design.768 lb/cu yd q FA = 10. A close examination of Figure 3-4 shows the wall cross-section is a trapezoid that is 14 feet. Step 4. Cement = 7. 8 inches wide on one end. 9 inches high. determine the total amount of materials needed to construct the retaining wall shown in Figure 3-4.FM 5-428 Chaptr 3 Proportioning Concrete Mixtures Step 1. SAMPLE PROBLEM FOR MATERIALS NEEDED FOR MIX DESIGN 3-21.05 sacks (Type IA) q Water = 36. Determine the total volume of concrete required. Water is required on concrete projects not only for mixing but for wetting the forms. Step 3. not all of this water will be used for the concrete.5 cu ft or 1. add l0 percent. A planning factor of 8 gallons of water for each sack of cement is usually sufficient. and CA. Step 2. Determine the required amount of water needed for the job. however. An easy way to do this is to break the project up into simple geometric shapes.6 gal q CA = 17. tools. Divide the retaining wall into two sections. If the total volume is greater than 200 cubic yards. and curing the concrete.0 cu ft or 1.
FM 5-428 Chaptr 3 Proportioning Concrete Mixtures Figure 3-4. Retaining wall 3-18 .
960 gallons q CA = 62 tons q FA = 38 tons 3-19 . the waste factor is10 percent).05 sacks/cu yd x 70.918.1 cu yd Step 3.3 lb or 38 tons Step 4.936.1 cu yd = 75. Determine the amount of water required for cleanup and mixing.1 cu yd = 123.768 lb/cu yd x 70. Total volume + waste = 63.8 lb or 62 tons FA 1.1 cu yd = 494.2 sacks = 495 sacks NOTE: Round values up to the next whole number since you cannot order partial sacks.960 gallons SUMMARY 3-22.10 = 70. Calculate the waste factor (since the volume is less than 200 cubic yards. Summary of the amounts of materials to be ordered for the project are as follows: q Cement = 495 sacks q Water = 3. Determine the amounts of cement and aggregates needed.083 lb/cu yd x 70.FM 5-428 Chaptr 3 Proportioning Concrete Mixtures Step 2. Water required = 495 sacks x 8 gallons per sack = 3.7 cu yd x 1. Cement 7. CA 1.
You must also consider the concrete's final shape. SECTION I. metal or other suitable material to harden or set. dimensions. Formwork should be strong enough to support the concrete's weight and rigid enough to maintain its position and appearance. Loose forms permit either loss of cement. The nature of the structure. Because formwork can represent up to one-third of a concrete structure's total cost. produces the desired shapes. Forms also protect concrete. holding to close dimensional tolerances. and surface finish. you must know the strength of the forming materials and the loads they support. It is desirable to maintain a repetition of identical units so that the forms may be removed and reused at other locations with a minimum amount of labor. PRINCIPLES IMPORTANCE OF FORM DESIGN 4-2. Formwork holds concrete until it sets. Brace forms enough to align them and to strengthen them enough to hold the concrete.FM 5-428 Chptr 4 Form Design and Construction Chapter 4 Form Design and Construction 4-1. and familiarity with construction methods all influence the formwork design. and strong. The concrete in this and other types of construction. Take special care in bracing and tying down forms used for such configurations as retaining walls that are wide at the bottom and taper toward the top. availability of equipment and form materials. The wet mixture is placed in forms constructed of wood. The form must be assembled with quality workmanship. tends to lift the form above its proper elevation. To reuse forms. To design forms. make them easy to remove and replace without damage. resulting in honeycomb. 4-1 . and develops a desired surface finish. or loss of water causing sand to streak. this phase of a project is very important. rigid. Forms must be tight. An inherent property of concrete is that it can be transformed into any shape. FORM CHARACTERISTICS 4-3. aid in curing. formwork must be tight enough to prevent the water seepage and designed to permit ready removal. particular care should be exercised in its design. In addition. Because the formwork for a concrete structure constitutes a considerable item in the cost of the completed structure. anticipated reuse of the forms. such as the first pour for walls and columns. and support any reinforcing bars or conduit embedded within the concrete.
FM 5-428 Chptr 4 Form Design and Construction
4-4. Forms are generally made from four materials--wood, metal, earth, and fiber. WOOD 4-5. Wood materials are the most common form materials by far, because they are economical, easy to produce and handle, and can adapt to many shapes. For added economy, you can reuse form lumber for roofing, bracing, and similar purposes. Soft wood, such as pine, fir, and spruce, makes the best and most economical form lumber because it is light, easy to work with, and available almost everywhere. Form lumber must be straight, structurally sound, strong, and only partially seasoned. Kiln-dried lumber tends to swell when soaked with water from the concrete. If the form is tightly jointed, the swelling can cause bulging and distortion. When using green lumber, either allow for shrinkage or keep the forms wet until the concrete is in place. Lumber that contacts concrete should be finished at least on one side and on both edges. The edges can be square, shiplap, or tongue and groove. The last finish makes a more watertight joint and helps prevent warping. Use plywood identified for use in concrete forms for wall and floor forms if it is made with waterproof glue. Plywood is more warp-resistant and can be reused more often than lumber. It is available in thickness of 1/4, 3/8, 9/16, 5/8, and 3/4 inch, and in widths up to 48 inches. The 5/8 and 3/4 inch thicknesses are more economical because the thinner sections require solid backing to prevent deflection. However, the 1/4 inch thickness is useful for curved surfaces. Although longer lengths are available, 8-foot plywood is the most common. METAL 4-6. Metal materials are used for added strength or when a construction will be duplicated at more than one location. They are initially more expensive than wood forms but are more economical in the long run if reused often enough. Steel forms are common for large, unbroken surfaces such as retaining walls, tunnels, pavements, curbs, and side-walks. They are especially useful for sidewalks, curbs, pavements, and precast-concrete operations because you can use them many times. EARTH 4-7. Earth materials are acceptable in subsurface construction if the soil is stable enough to retain the desired concrete shape. The advantages of earth forms are that they require less wood construction and resist settling better than other types of forms. Their obvious disadvantages are rough surface finish and the requirement for more excavation. Therefore, earth forms are generally restricted to footings and foundations. FIBER 4-8. Fiber forms are prefabricated and are filled with waterproofed cardboard and other fiber materials. Successive layers of fiber are first glued together and then molded to the desired shape. Fiber forms are ideal for round concrete columns and other applications where preformed shapes are feasible because they require no form fab-rication at the job site and thus save considerable time.
FM 5-428 Chptr 4 Form Design and Construction
4-9. Forms are assembled and used to make walls. Figure 4-1 shows the basic parts of a wood form for panel walls.
Figure 4-1. Wood form for a concrete panel wall SHEATHING 4-10. Sheathing forms the ver-tical surfaces of a concrete wall but runs horizontally itself. The sheathing edges and the side that contacts the concrete should be finished as smooth as possible, especially for an exposed final concrete surface. The sheathing must also be watertight. Sheathing made from tongue-and-groove lumber gives the smoothest and most watertight concrete surface. Plywood or fiber-based hardboard can also be used. STUDS 4-11. The weight of the plastic concrete will cause the sheathing to bulge if it's not reinforced by studs. Therefore, vertical studs add rigidity to the wall form. The studs are made from single 2 by 4s or 2 by 6s. WALES (WALERS) 4-12. Wales reinforce the studs when they extend upward more than 4 or 5 feet. They should be made from doubled 2 by 4s or 2 by 6s, and are lapped at the form corners to add rigidity. Double wales not only reinforce the studs but also tie prefabricated panels together and keep them aligned. BRACES
FM 5-428 Chptr 4 Form Design and Construction
4-13. Although braces are neither part of the form design nor considered as providing any additional strength, they help stabilize the form. The most common brace is a combination of a diagonal member and a horizontal member nailed to a stake at one end and to a stud or wale at the other end. The diagonal member makes a 20- to 60-degree angle with the horizontal member. To add more bracing, place vertical members (strongbacks) behind the wales or in the angle formed by intersecting wales. SPREADERS 4-14. Spreaders are small pieces of wood placed between the sheathing panels to maintain the proper wall thickness between them. They are cut to the same length as the wall thickness. Spreaders can be removed easily before the concrete hardens since friction, not fasteners, hold them in place. Attach a wire securely through the spreaders, as shown in Figure 4-1 to pull them out when the fresh concrete exerts enough pressure against the sheathing to permit removal. TIE WIRES 4-15. Tie wires secure the formwork against the lateral pressure of the plastic concrete. They always have double strands. TIE-RODS (SNAP-TIES) 4-16. Tie-rods sometimes replaces tie wires in the same function because working with rods are easier. COLUMN FORMS 4-17. Figure 4-2 shows the basic parts of a wood form for a concrete column.
FM 5-428 Chptr 4 Form Design and Construction
Figure 4-2. Form for a concrete column and footing SHEATHING 4-18. Sheathing runs vertically in column forms to reduce the number of saw cuts. Nail the corner joints firmly to ensure watertightness. YOKES 4-19. A yoke is a horizontal re-inforcement in the form of a rectangle that wraps around a column to prevent the plastic concrete from distorting the form. It serves the same purpose as a stud in a wall form. You can lock yokes in place using the sheathing-, scab-, or bolt-type yoke lock. The small horizontal dimensions of a column do not require vertical reinforcement. BATTENS 4-20. Battens are narrow strips of boards that are placed directly over the joints to fasten several pieces of vertical sheathing together. FOOTING FORMS 4-21. Footing forms are shown in Figure 4-2 and are discussed in paragraph 4-49. SECTION II. DESIGN
FM 5-428 Chptr 4 Form Design and Construction
4-22. Forms are the molds that hold the plastic concrete and support it until it hardens. They must keep deflections within acceptable limits, meet dimensional tolerances, prevent paste leakage, and produce a final product that meet appearance needs. Therefore, strength, rigidity, and watertightness are the most important form design considerations. In addition, forms must support all weights and stresses to which they are subject, including the dead load (DL) of the forms; the weight of people, equipment, and materials that transfers to the forms; and any impact due to vibration. Although these factors vary with each project, do not neglect any of them when designing a form. Ease of erection and removal are other important factors in economical form design. Sometimes you may want to consider using platforms and ramp structures that are independent of the formwork because they prevent form displacement due to loading, as well as impact shock from workers and equipment.
4-23. Concrete is in a plastic state when placed in the designed form; therefore, it exerts hydrostatic pressure on the form. The basis of form design is to offset the maximum pressure developed by the concrete during placing. The pressure depends on the rate of placing and the ambient temperature. The rate of placing affects pressure because it determines how much hydrostatic head builds up in the form. The hydrostatic head continues to increase until the concrete takes its initial set, usually in about 90 minutes. However, because the initial set takes more time at low ambient temperatures, consider the ambient temperature at the time of placement. Knowing these two factors (rate of placement and ambient temperature) plus the specified type of form material, calculate a tentative design.
4-24. It is best to design forms following a step-by-step procedure. Use the following steps to design a wood form for a concrete wall. Step 1. Determine the materials needed for sheathing, studs, wales, braces, and tie wires or tie-rods. Step 2. Determine the mixer output by dividing the mixer yield by the batch time. Batch time includes loading all ingredients, mixing, and unloading. If you will use more than one mixer, multiply the mixer output by the number of mixers.
Step 3. Determine the area enclosed by the form. Plan area (sq ft) = Length (L) x Width (W) Step 4. Determine the rate (vertical feet per hour) of placing (R) the concrete in the form by dividing the mixer output by the plan area.
FM 5-428 Chptr 4 Form Design and Construction
NOTE: If using wood for an economical design, try to keep R < 5 feet per hour. Step 5. Estimate the placing temperature of the concrete. Step 6. Determine the maximum concrete pressure (MCP) using the rate of placing (see Figure 4-3 or the formula above the figure). Draw a vertical line from the rate of placing until it intersects the correct concrete-temperature line. Read left horizontally from the point of intersection to the left margin of the graph and determine the MCP in 100 pounds per square foot.
Figure 4-3. MCP graph Step 7. Find the maximum stud spacing (MSS) in inches. Use Table 4-1 for board sheathing orTable 4-2 for plywood sheathing. Refer to the column headed maximum concrete pressure (MCP) and find the value you have for the MCP. If the value falls between two values in the column, round up to the nearest given value. Move right to the column identified by the sheathing thickness. (Always use the strong way for plywood when possible). This number is the MSS in inches.
400 2.200 11 1. in Pounds per Square Foot Nominal Thickness of S4S Boards.600 1.100 11 1.200 2. in Inches 1 1 1/4 37 34 33 31 30 29 26 24 22 20 18 17 16 15 15 14 13 12 12 11 10 10 10 1 1/2 2 44 50 41 47 39 44 37 42 35 41 34 39 31 35 29 33 27 31 25 30 23 28 22 26 20 24 19 23 18 22 18 22 16 20 15 18 14 17 14 16 13 16 12 15 12 14 75 30 100 28 125 26 150 25 175 24 200 23 300 21 400 18 500 16 600 15 700 14 800 13 900 12 1.000 2.600 9 9 8 8 7 7 4-8 .FM 5-428 Chptr 4 Form Design and Construction Table 4-1.000 12 1.800 2. Maximum stud (joist) spacing for board sheathing Maximum Concrete Pressure.400 10 1.
500 4-9 Weak Way .400 1.100 1. the Stud in Pounds per 1/2 5/8 3/4 1 Square (7 ply) Foot 75 100 125 150 175 200 300 400 500 600 700 800 900 1.5-Ply Sanded Concrete Face. in inches Maximum Strong Way .FM 5-428 Chptr 4 Form Design and Construction 2. Grain Perpendicular to Pressure.000 7 7 9 9 12 14 11 13 Table 4-2.800 3. Maximum stud (joist) spacing for plywood sheathing.000 1. Grain Parallel to the Stud 1/2 5/8 3/4 1 (7 ply) 30 28 27 25 24 24 21 19 18 17 16 15 15 14 12 11 11 10 9 20 18 17 16 15 15 13 12 11 10 10 9 9 8 7 7 6 6 5 24 22 20 19 18 17 15 14 13 12 11 10 10 9 9 8 8 7 7 26 24 23 22 21 20 17 16 15 14 13 12 11 10 10 10 9 9 9 31 29 28 27 26 25 22 20 19 17 16 15 14 13 12 11 11 10 9 13 12 11 11 10 10 8 8 7 6 6 5 4 4 4 - 18 17 15 15 14 13 12 11 10 9 9 8 8 7 6 6 5 5 5 23 22 20 19 18 17 15 14 13 12 11 11 9 9 8 7 7 6 6 .5-Ply Sanded Face.300 1.200 1.
for whales.700 1.FM 5-428 Chptr 4 Form Design and Construction 1.800 1. in inches.900 2. Refer to the column headed uniform load and find the value for the ULS. Maximum spacing. round it up to the nearest given value. and 4" x 4 or larger shores where member to be supported is a SINGLE menber Uniform Load in Pounds per Linear Foot 100 125 150 Supported Members Size (S4S)* 2x4 60 54 49 2x6 95 85 77 3x6 120 440 100 4x4 92 80 75 4x6 131 124 118 4-10 . Determine the uniform load on a stud (ULS) by multiplying the MCP by the stud spacing divided by 12 inches per foot. in pounds per linear foot Step 9. stringers. Where-MCP = maximum concrete pressure. Table 4-3. Determine the maximum wale spacing (MWS) using Table 4-3. This number is the MWS in inches.200 2.000 2. Move right to the column identified by the size of the stud you are using.000 5 5 4 4 4 4 - 6 6 6 5 5 5 4 4 4 - 8 8 8 8 7 6 5 5 4 4 9 8 8 7 7 6 6 5 5 5 - 4 4 4 4 - 5 5 5 4 4 4 4 - 9 8 8 7 7 6 6 5 5 5 Step 8. ties.600 1. in pounds per square foot MSS = maximum stud spacing ULS = uniform load stud.400 2.600 2.800 3. If the value falls between two values in the column.
400 1.400 45 42 40 38 36 35 32 30 28 27 24 22 21 20 19 17 16 15 14 13 13 12 12 11 11 10 72 67 62 60 57 55 50 47 44 41 38 36 33 31 30 27 25 23 22 21 20 19 19 18 17 16 93 87 82 77 74 71 65 61 58 55 50 46 43 41 38 35 33 31 29 27 26 25 24 23 22 21 70 65 61 58 55 53 49 46 43 41 37 35 32 30 29 27 25 23 22 21 20 19 18 17 17 16 110 102 97 92 87 84 77 72 68 65 59 55 51 48 46 42 39 36 34 32 31 30 28 27 26 25 4-11 .800 2.000 1.000 2.000 3.400 2.600 2.800 3.200 2.FM 5-428 Chptr 4 Form Design and Construction 175 200 225 250 275 300 350 400 450 500 600 700 800 900 1.600 1.200 1.
either single or double). Determine the uniform load on a wale (ULW) by multiplying the MCP by the MWS and dividing by 12 inches per foot. divided by 12 inches per foot ULW = uniform load on wale. for ties and 4" x 4" or larger shores where member to be supported is a double member Uniform Load. Step 10. in inches. round it up to the nearest given value. Determine the tie spacing based on the ULW using Table 4-3 or Table 4-4 (depending on type of wale. in inches. Move right to the column identified by the size of wale you are using. in inches. in pounds per square foot MWS = maximum wale spacing. in pounds per linear foot Step 11. If the value falls between two values in the column. Refer to the column headed Uniform Load and find the value for the ULW.500 10 9 15 14 20 18 15 13 23 21 *S4S indicates surfaced four sides. Maximum spacing. This number is the maximum tie spacing. in Pounds per Linear Foot 100 125 150 175 200 225 250 275 300 Supporting Member Size (S4S) 2x4 85 76 70 64 60 57 54 51 49 2x6 126 119 110 102 95 89 85 84 77 3x6 143 135 129 124 120 116 109 104 100 4x4 222 105 100 96 92 87 82 78 75 4x6 156 147 141 135 131 127 124 121 118 4-12 . Table 4-4.FM 5-428 Chptr 4 Form Design and Construction 3.800 4. based on wale size. Where-MCP = maximum concrete pressure.
000 2. If the breaking strength of the tie is unknown.200 2. Determine the tie spacing based on the tie strength by dividing the tie breaking strength by the ULW.400 3.000 3.800 2.400 1.200 1.500 46 43 40 38 35 32 30 28 27 25 23 21 20 19 18 17 17 16 15 14 14 12 72 67 63 60 55 51 47 44 43 39 36 34 32 30 29 27 26 25 24 23 21 20 93 87 82 77 71 65 61 58 55 50 46 43 41 39 37 36 34 33 32 30 28 25 70 65 61 58 53 49 46 43 41 38 35 33 31 29 28 27 26 25 24 22 21 19 110 102 97 92 81 77 72 68 65 59 55 51 48 46 44 42 40 39 38 35 33 30 Step 12. use Table 4-5 to find the breaking loads for a double-strand wire and tie-rods (found in the Army supply system).FM 5-428 Chptr 4 Form Design and Construction 350 400 450 500 600 700 800 900 1.600 1. Where-4-13 .800 3.600 2.000 1.800 4.400 2.
170 930 4-14 .000 950 660 950 650 850 1. Average breaking load of tie material.420 1. in pounds Steel Wire Size of Wire Gage Minimum Breaking Number Load Double Strand. round the value down to the next whole number. Select the smaller of the tie spacing as determined in steps 11 and 12.000 3. Table 4-5.700 1.FM 5-428 Chptr 4 Form Design and Construction Tie wire or tie-rod = strength = average breaking load (see Table 4-5) ULW = uniform load on wales. in Pounds 8 9 10 11 Barbwire Size of Wire Gage Minimum Breaking Number Load 12 1/2 13* 13 1/2 14 15 1/2 Tie-rod Description Snap ties Pencil roads *Single-strand barbwire Step 13. Minimum Breaking Load. in pounds per square foot NOTE: If the result does not equal a whole number. in Pounds 3.
Determine the number of studs on one side of a form by dividing the form length by the MSS. Step 3. Studs: 2 x 4 (single) Wales: 2 x 4 (double) Sheathing: 1-inch board Ties: Number 9 wire Step 2. Step 16. The first and last studs must be placed at the ends of the form. Place the first wale one-half of the maximum space up from the bottom and place the remaining wales at the MWS. even though the spacing between the last two studs may be less than the maximum allowable spacing. Calculate the rate of placing. The concrete placing temperature is estimated at 70° F. The form materials are 2 by 4s. and 10 feet high. The solution steps are as follows: Step 1. Step 4. 4-15 . Install tie wires at the intersection of studs and wales. and number 9 black annealed wire. Design a form for a concrete wall 40 feet long. SAMPLE FORM DESIGN PROBLEM MUMBER ONE 4-25. 1-inch board sheathing. An M919 concrete mobile mixer is available and the crew can produce and place a cubic yard of concrete every 10 minutes. Reduce the stud spacing (step 7) or the tie spacing (step 13) to conform with this requirement. Calculate the plan area of the form. NOTE: The length of the form is in feet. Lay out available materials. and round up to the next integer. Place the first tie at one-half the maximum tie spacing from the end of the wale. Add one to this number and round up to the next integer. Step 17. Determine the time required to place the concrete by dividing the height of the form by the rate of placing. 2 feet thick. Calculate the production rate. Determine the number of wales for one side of a form by dividing the form height by the MWS. The stud spacing is in inches.FM 5-428 Chptr 4 Form Design and Construction Step 14. Step 15. tie-rods may be placed along the wales at the spacing (determined in step 13) without adjusting the studs.
FM 5-428 Chptr 4 Form Design and Construction Step 5. Temperature = 70o Step 6. Determine the MWS (refer to Table 4-3). Calculate the ULS. Determine the maximum tie spacing. Estimate the time required to place concrete. Step 9. Determine the tie-wire spacing based on wale size (refer to Table 4-4). MWS = 24 inches Step 10. MCP = 400 pounds per square foot Step 7. Reduce the tie spacing to 18 inches since the maximum tie spacing is greater than MSS. Calculate the number of double wales per side. Determine the MSS (refer to Table 4-1). Calculate number of studs per side. Tie-wire spacing = 30 inches. breaking strength of number 9 wire = 1. Calculate the ULW. Step 16. MSS = 18 inches Step 8. tie at the intersection of each stud and double wale. Tie spacing = 21 inches Step 14. Step 17. Determine the MCP (refer to Figure 4-3).420 pounds). 4-16 . Determine the tie-wire spacing based on wire strength (referring to Table 4-5. Determine the concrete-placing temperature. Step 15. Step 11. Step 12. Step 13.
Temperature = 70° F Step 6. Determine the ULW.000-pound (breaking strength) snap ties. Calculate rate the of placing.FM 5-428 Chptr 4 Form Design and Construction SAMPLE FORM DESIGN PROBLEM NUMBER TWO 4-26. and 3. Determine the MCP (refer to Figure 4-3). Determine the concrete placing temperature. Calculate the plan area of form. MCP = 500 pounds per square foot Step 7. Step 9. Determine the MWS (refer to Table 4-3 using 700 pounds per foot load). 2 feet thick. The concrete placing temperature is estimated to be 70° F. Step 3. Calculate the production rate. Design the form for a concrete wall 40 feet long. and 10 feet high. Step 5. Determine the MSS (refer to Table 4-2). MSS = 15 inches Step 8. Step 4. Studs: 2 x 4 (single) Wales: 2 x 4 (doubled) Sheathing: 3/4-inch plywood (strong) Ties: Snap ties (3. The following steps will be used: Step 1. MWS = 22 inches Step 10.000 pounds) Step 2. An M919 concrete mobile mixer is available and the crew can produce and place a cubic yard of concrete every 7 minutes. Determine the ULS. 3/4-inch thick plywood. 4-17 . Lay out available needed materials. The materials for constructing the form are 2 by 4s.
Step 17. Calculate the number of studs per side. vibration. we need to determine the maximum safe spacing of these braces (center-to-center) that will keep the formwork aligned. seasoned lumber will be used and that the braces are properly secured against the wall forms and the ground (both ends are secured). Step 15. accidents). Determine the tie spacing based on wale size (refer to Table 4-4. The design procedure is based on using a single row of braces and assumes that strong. Tie spacing = 27 inches Step 14. As this force can act in both directions. NOMENCLATURE 4-28.5 times the wall height. Step 13. Calculate the number of double wales per side. or braces should be used on both sides of the wall forms.FM 5-428 Chptr 4 Form Design and Construction Step 11. personnel. BRACING FOR WALL FORMS 4-27. straight. Determine the maximum tie spacing. Braces are used against wall forms to keep them in place and in alignment and to protect them from mishaps due to external forces (wind. Once we know the height of the wall to be built and have selected a material (2 inches or greater) for the braces. braces to be used should be equally strong in tension as in compression. in feet. Tie spacing = 27 inches Step 12. it is not necessary to adjust the tie/stud spacing. An equivalent force due to all of these forces (the resultant force) is assumed to be acting uniformly along the top edge of the form in a horizontal plane. equipment. Determine the tie spacing based on tie-rod strength (refer to Table 4-5). this force is assumed to be 12. Insert the first tie-rod one-half the spacing from the end and one full spacing thereafter. 4-18 . Estimate the time required to place concrete. using 1. See Figure 4-4. Step 16. Because tie-rods are being used.000 pounds per load). For most military applications. The following terms are used in bracing for a form wall.
L = the actual unsupported length. Lmax = the maximum allowable unsupported length of the brace. due to buckling and bending. q q q q q q q q q cos = cosine: the ratio of the distance from the stake to the wall (x) divided by the length of the brace (LB. for all 4-inch material. of the brace member from end connection to end connection. of the wall form. center-to-center. that the brace makes with the horizontal shoe brace. see Table 4-6.FM 5-428 Chptr 4 Form Design and Construction q q LB = total length. Smax = the maximum safe spacing of braces (feet). in feet. For all 2-inch material. of the brace used. L max = 14 1/2 feet. For the best effect. in feet. 0 = the angle. in degrees. h = the overall height. to support the walls against external forces. Lmax = 6 1/4 feet. in feet.) sin = sine: the ratio of the height of the brace (y) divided by the length of the brace (LB. J = a factor to be applied which includes all constant values (material properties and assumed wind force). measured in feet from the base of the form.) 4-19 . in feet. y = the point of application of the brace on the wall form. the angle should be between 20 and 60 degrees. It is measured in feet4.
in Inches J. J factor Material. In Feet4 4-20 .FM 5-428 Chptr 4 Form Design and Construction Figure 4-4. Elements of diagonal bracing Table 4-6.
Determine the angle of placement. The design procedure can best be explained by the example problem that follows: Step 1. 4-21 . Since the Lmax for all 2-inch material is 6 1/4 feet and the brace in this problem is 10 feet long. 0 = sin-1 (.inches by 10-feet brace applied to the top edge of the wall form at y = 6 feet. Determine the L which is the actual unsupported length of brace. connect all braces to each other at the center so deflection does not occur. 4-30. place these braces no further apart than 7 feet.010 4-29. Using 2.890 6. thus giving L = 5 feet. Step 4.360 3. The best position for this support would be in the middle of the brace. Use 2-by 6.240 7. Determine the spacing of braces for a wall 10 feet high. The following selected materials are given: q J = 3. Determine the Smax from the formula.590 30.710 feet4 (from Table 4-6) q q q q Lmax = 6 1/4 feet (because of the 2-inch material) LB = 10 feet h = 10 feet (from example problem) y = 6 feet (from example problem) Step 2.inch by 10-foot material. attached 6 feet from the bottom of the form.by 6. we will have to use something to support the braces (usually a 1 by 4 or a 1 by 6). 0. After the braces are properly installed.FM 5-428 Chptr 4 Form Design and Construction 2x4 2x6 2x8 2 x 10 2 x 12 4x4 PROCEDURE 2.600) = 37o Step 3.710 4.
To prevent overloading the brace. Joists. Supports the joists against deflection. the following points lend insight to the formula. Stringers. q q q Derivation of the formula has a safety factor of 3. The following terms are used in the form design (see Figure 4-5). but never use lumber smaller than 4 by 4s. Performs the same function as wales in a wall form. 3-. Lumber at least as large as the stringer should be used. This is necessary to prevent crushing of the brace. For older or green lumber. Lateral bracing. There may be instances where a concrete slab will have to be placed above the ground such as bunker and culvert roofs. To fully understand the procedure. q q q OVERHEAD SLAB FORM DESIGN 4-32. Cross bracing. Cross bracing will always be required to support the formwork materials. Bracing may be required between adjacent shores to keep shores from bending under load. Supports the sheathing against deflection. Performs the same functions as ties in a wall form and also supports the concrete at the desired elevation above the ground. Carefully consider the design of the formwork because of the danger of failure caused by the weight of plastic concrete and the live load (LL) of equipment and personnel on the forms. or 4-inch thick lumber. There is no doctrine that states the braces must be placed 7 feet apart--they can be less.FM 5-428 Chptr 4 Form Design and Construction NOTE: This procedure determines the maximum safe spacing of braces. NOMENCLATURE 4-33. Use 2-. Use 2-inch thick or larger lumber. 4-22 . Stringers do not have to be doubled as wales are. For maximum support. q q q q q q Sheathing. Use 1 by 6s or larger material for bracing material. attach braces to the top edge of the forms (or as closely as practicable). Supports the stringers against deflection. Whenever there are choices of material. reduce Smax according to judgment. the larger size will always carry greater loads. Performs the same function as studs in a wall form. Shores. Shapes and holds the concrete. Plywood or solid sheet metal is best for use. The overhead slab form design method employs some of the same figures used in the wall-form design procedure. place supports a minimum of 2 feet apart for all 2-inch material and 5 feet apart for all 4-inch material. better support will be achieved when 0 = 45o Remember to use intermediate supports whenever the length of the brace (LB) is greater than Lmax. Also. DISCUSSION 4-31.
FM 5-428 Chptr 4 Form Design and Construction q q Wedges. It is important that anyone using your design will know exactly the materials to use for each of the structural members. Lay out and specify the materials you will be using for the construction of the overhead roof slab. The LL of materials. Typical overhead slab forms DESIGN PROCEDURE 4-34. Use the following steps in determining form design: Step 1. Wood or metal shims used to adjust shore height Mudsill. and equipment is estimated to be 50 pounds per square foot 4-23 . Figure 4-5. Board which supports shores and distributes the load. Use 2-inch thick or larger lumber. Step 2. personnel. Determine the maximum total load (TL) the formwork will have to support.
The concrete's DL is obtained using the concrete's unit weight of 150 pounds per cubic foot. select the allowable load on the shore both ways as follows: (NOTE: The unsupported length is equal to the height above the sill--sheathing thickness. The formulas are-TL = LL + DL LL = 50 lb/sq ft. Determine the maximum shore spacing the following two ways: q Determine the maximum shore spacing based on the stringer strength. In this case. in Inches 4x4 4x6 6x6 4-24 . Step 6. This is the same procedure used in determining the MSS for wall-form design. This length is then rounded up to the next higher table value. rounded to the next higher load shown in the left column of the table. based on shore strength Nominal Lumber Size. Step 5. Read right to the column containing the lumber material used as the joist. Calculate the uniform load on the joists (ULJ). The same procedure is used as determining uniform loads on structural members in wall-form design. Use Table 4-3 orTable 4-4 (depending on the type of stringer) and the ULSstr. Step 4. Use Table 4-1. This determination is dependent on both the shore strength and the end bearing of the stringer on the shore. The LL is added with the DL of the concrete to obtain the maximum TL. The value at this intersection is the on-center (OC) spacing of the stringer. joist thickness. Use the maximum TL in place of the MCP. and stringer thickness. This intersection is the maximum OC spacing of the shore required to ensure the stringer is properly supported. Using Tables 4-7 and Table 4-8. Use Table 4-3 and the ULJ calculated in step 4. Determine the maximum stringer spacing. This is the member to be supported by the stringer. a LL of 75 pounds per square foot will be used. or 75 lb/sq ft with power equipment Step 3. Allowable load (in pounds) on wood shores. Read right to the stringer material column.FM 5-428 Chptr 4 Form Design and Construction unless the formwork will support engine-powered concrete buggies or other power equipment. Step 7. Calculate the uniform load on the stringer (ULSstr). Determine the maximum joist spacing.) Table 4-7. q Determine the maximum shore spacing based on the allowable load. or Table 4-2 and determine the joist spacing based on the sheathing material used. Round this load up to the next higher load located in the left column of the table.
700 22.900 9.600 3.500 9.100 6.700 16.700 2.100 4.400 2.FM 5-428 Chptr 4 Form Design and Construction Unsupported Length.800 10.700 11.000 23.300 8.500 19.000 21.800 11.800 2.700 22. The above table values are based on wood members with the following characteristics strength: Compression parallel to gram = 750 psi.700 6. based on bearing stresses where the maximum shore area is in contact with the supported member 4-25 .100 l/d = 50 2.700 3.700 22.000 5.900 4.100 5.200 7.700 2.100. Table 4-8.300 3.000 psi.200 7.700 5.300 3.700 10.000 3.700 22. R indicates rough lumber.200 NOTES: 1.600 6.400 l/d = 50 14 2.600 7.300 15.600 12.900 8.100 6.000 14.700 14. E = 1.600 S4S R S4S 14.200 3.400 4.700 23.700 14. 2.000 7.300 6.200 9.300 2.200 13.300 12. in pounds.700 22.000 l/d = 50 1.400 2.500 5.700 22.400 23.400 23.900 7.400 23. Allowable load on specified shores. in Feet 4 5 6 7 8 9 10 11 12 13 R 9.700 15 1.000 l/d = 50 R 15.000 23.400 5.000 17.700 9.200 9.300 S4S 9.800 5.900 9.200 9.300 15.400 23.000 4.200 4.700 8.
use the lowest value provided in Table 4-8. with the shore spacing based on the allowable load in step 7. Check the shore bracing.100 5100 4800 350 385 400 NOTES: 4600 5100 5300 7900 7600 4300 7100 6700 11100 10600 4700 7800 7400 12200 11600 4900 8200 7700 12700 12100 1. Determine the most critical shore spacing. S4S indicates surfaced on four sides. If the C ⊥ to the grain is unknown. Calculate shore spacing by the following formula: Step 8. .Compare the two loads just determined and select the lower as the maximum allowable load on the shore to be used in the formula below.FM 5-428 Chptr 4 Form Design and Construction Nominal Lumber Size. Read down the left column to the unsupported length of the shore. then read right to the column of the size material used as the shore. . The allowable load for shore is given in pounds at the intersection. . Read down the left column to the C ⊥ to the grain of the stringer material and then right of the column of the shore material. See Table 4-7.300 3. R indicates rough lumber. Select the size of the shore material and the compression C perpendicular (⊥) to the grain of the stringer. The allowable load between the stringer and the shore will be in pounds. Compare the shore spacing based on the stringer strength in step 7. Select the shore material dimensions and determine the unsupported length in feet of the shore.First. 2. determine the allowable load based on the shore strength. Step 9. determine the allowable load based on end bearing area. assume the most critical C is ⊥ to the grain. When the compression perpendicular to the grain of the member being supported is unknown. in Inches C ⊥ of Member Supported R 4x4 S4S R 4x6 S4S R 6x6 S4S 250 3. Select the smaller of the two spacings.Second. Verify that the unbraced length (l) of the shore (in inches) divided by the least dimension (d) of 4-26 . 3.
the lateral and cross bracing must be provided. It is good engineering practice to provide both lateral and diagonal bracing to all shore members if material is available. Design the form for the roof of a concrete water tank to be 6 inches thick. and 30 feet long. If l/d exceeds 50. Determine the maximum TL. Load = 275 pounds per foot Joist material = 4 x 4 Maximum stringer spacing = 55 inches 4-27 . Calculate the ULJ. Use the following steps in design: Step 1. 3/4-inch plywood (strong way) and TL = 150 pounds per square foot Joist spacing = 22 inches Step 4. Determine the maximum joist spacing using Table 4-2. LL = personnel and equipment = 75 lb/sq ft TL = DL + LL TL = 75 lb/sq ft + 75 lb/sq ft TL = 150 lb/sq ft Step 3. Lay out available materials for construction. Available materials are 3/4-inch plywood and 4 by 4 (S4S) (surfaced on four sides) lumber. The slab will be constructed 8 feet above the floor (to the bottom of the slab). Mechanical buggies will be used to place concrete. 20 feet wide. SAMPLE FORM DESIGN PROBLEM NUMBER THREE 4-35. Step 5. Table 4-7 indicates the l/d > 50 shore lengths and can be used if the shore material is sound and unspliced.FM 5-428 Chptr 4 Form Design and Construction the shore does not exceed 50. Sheathing: 3/4-inch plywood (strong way) Joists: 4 x 4 (S4S) Shores: 4 x 4 (S4S) Stringers: 4 x 4 (S4S) Step 2. Determine the maximum stringer spacing using Table 4-3.
Calculate the shore spacing as follows: Step 9.FM 5-428 Chptr 4 Form Design and Construction Step 6. Check shore deflection. Use the maximum shore spacing shown in Table 4-3 single member stringers. Select the most critical shore spacing.3/4 inch . and the allowable load for a 4 by 4 (S4S) = 3.3 1/2 inches .5 pounds per foot (round up to 700 pounds per foot) Stringer material = 4 x 4 (S4S) Maximum shore spacing = 35 inches. Calculate the ULSstr.3 1/2 inch . For an 8-foot 4 by 4 (S4S). Determine both ways as follows: q Allowable loads based on shore strength are shown in Table 4-7.25 inches 4-28 . The spacing determined in step 7 is less than the spacing determined in step 8. Since we do not know what species of wood we are using. 3. q Select the most critical of the two loads determined. q q q Load = 687. Step 10.400 pounds. the (C ⊥) to the grain = 250.100 pounds is the critical load.100 pounds based on end bearing stresses. Unsupported length = 8 feet . the shore spacing to be used is 35 inches. This determination is based on both the shore strength and end bearing stresses of the stringer to the shore. Step 7.3 1/2 inches = 7 feet 4 1/4 inches = 88. based on shore strength. based on stringer strength Step 8. Determine shore spacing based on allowable load. Determine the maximum shore spacing based on stringer strength. therefore. the allowable load = 5.3/4 inch . Since the (C ⊥) is less than the allowable load on the shore perpendicular to the grain (II). Unsupported length = 8 feet . we must assume the worst case. Therefore.3 1/2 inches = 7 feet 4 1/4 inches (round up to 8 feet). For an allowable load based on end bearing stresses see Table 4-8.
the slab thickness is so excessive that materials and personnel are wasted in the construction. either thicken the edge by 50 percent and taper back to normal slab thickness at a slope of not more than 1 in 10 or use a grade beam to support the edge. the soil-bearing capacity must be considered. and 3 floors. In other cases. When the load will be applied at the edges of the concrete slab. The following three points apply to the design thickness: q The minimum slab thickness will be 4 inches for class 1. make plane for tile Concrete Finishing Technique Medium steel trowel 1 Light foot Residential or tile-covered 4-29 . 4-36. Use the following procedure. Sheathing: 3/4-inch plywood (strong way) Joists: 4 x 4 (S4S) lumber spaced 22 inches OC Stringer: 4 x 4 (S4S) lumber spaced 55 inches OC Shores: 4 x 4 (S4S) lumber spaced 35 inches OC Lateral braces: not required CONCRETE SLAB ON GRADE THICKNESS DESIGN 4-37. BASIC ASSUMPTIONS 4-38. Concrete slabs on grade are the most often constructed concrete projects by engineer units. Many slabs that are constructed fail because the thickness of the slab is not adequate. and figures for the design of concrete slab thickness in the field to eliminate possible failure or wasted materials. Cross bracing is always required. q q Only the load area and the flexural strength required will be considered using this method. as listed in Table 4-9. The load is usually the wheel load plus impact loading caused by the vehicle. tables. Whenever the loaded area exceeds 80 square inches. The controlling factor in determining the thickness of a floor on ground is the heaviest concentrated load the slab will carry. Table 4-9. Concrete floor classifications Class Usual Traffic Use Special Consideration Grade for drainage.FM 5-428 Chptr 4 Form Design and Construction d = least dimension of 4 x 4 (S4S) lumber = 3. Summary of materials needed for construction.5 inches NOTE: Lateral bracing is not required. 2.
two-course floor. wash if aggregate is to be exposed 3 Light foot and pneumatic wheels 4 Foot and pneumatic wheels* 5 Foot and wheel abrasive wear* 6 Foot and steel-tire vehicles severe abrasion Drives. heavy industrial Crown. Step 1. Determine the floor classification. trowel. sidewalks for residences Light industrial commercial Single-course industrial. exposed aggregate. special finish for nonslip Steel trowel. 6 Mesh reinforcing. Use Table 4-9 with the usual traffic and use of the 4-30 . bond breaker on old concrete surface. for a class 6. pitch joints Air entrainment Careful curing Float. 5. DESIGN PROCEDURE 4-39. garage floors. 4. color. minimum thickness 2 1/2 inches *Under abrasive conditions on floor surface. integral topping Bonded two-course. schools.FM 5-428 Chptr 4 Form Design and Construction 2 Foot Offices. churches. mix in surface Color shake. the exposure will be much more severe and a higher quality surface will be required for class 4 and 5. a mineral or metallic aggregate monolithic surface treatment is recommended. Use the following steps in design procedures for concrete slabs. hospitals Ornamental residential Nonslip aggregate. and broom Hard steel trowel and brush for nonslip Special hard aggregate float and trowel Surface leveled by screeding Special disc-type power floats with repeated steel troweling Careful curing Base Textured surface and bond Top Special aggregate and/or mineral or metallic surface treatment 7 Same as classes Unbonded topping 3. special Steel trowel.
Determine the equivalent static load (ESL). the requirements of ACI 318 and the contract documents should be met. in inches 1 2 3 4 5 6 base 6 topping** 7 2-4 2-4 2-4 1-3 1-3 2-4 0-1 1-3 Minimum Compressive Strength. Read to the right and select the f 'c in psi. The average of any five consecutive strength tests of continuously moist-cured specimens representing each class of concrete should be equal to or greater than the specified strength.8.500 4.000 3. Step 3. Recommended slumps and compressive strengths Class of Floors Slump Range.500 3.500 5. Determine the minimum compressive strength. 4-31 .000 . f 'c in Pounds per Square Inch*Use 3.000 NOTE: These recommendations are specially for concrete made with normal-weight aggregate.000 4. Note that this table gives the recommended slump range for the plastic concrete.FM 5-428 Chptr 4 Form Design and Construction slab. Step 2. The impact loading is 25 percent more than the static load (SL) for the vehicles. For structural slabs. Use the formula: Step 4. read down the class of floors column until you find the floor classification selected. The minimum is 846 pounds per cubic yard. **The cement content of the heavy-duty floor topping depends upon the severity of the abrasion.000 4. Using Table 4-10. Table 4-10. Determine the allowable flexural tensile stress f 't after the concrete f 'c is determined. The expected impact loading is needed for this step. *Refer to the minimum compressive strength of cylinders made and tested according to applicable ASTM standards for 28 days.500 3.
Using Figure 4-6. read up the left side until the TL is the same as the design CESL from 5 above. Maximum wheel loads for industrial floors Step 6.FM 5-428 Chptr 4 Form Design and Construction ESL = (1 + 25%) x SL Step 5. The slab thickness can then be determined by interpolating 4-32 . If this f 't is not equal to 300 psi. Read to the right until the loaded area (in square inches) for the slab design is intersected. Determine the slab thickness. The procedure for correction is as follows: Figure 4-6. This correction is necessary so that the standard thickness (see Figure 4-6) may be used to determine the required slab thickness. When calculating the allowable flexural tensile f 'c in step 4 above. then the ESL must be corrected based on a ratio between the standard (300 psi) and the actual f 't. an f 't was determined. Evaluate and correct the ESL if f 't is not equal to 300 psi.
q Always use nonfrost susceptible (free-draining) material under the slab. The surface will be exposed to foot and wheel traffic. Determine the minimum cement content and recommended air content for structures subjected to freeze-thaw cycles. SAMPLE SLAB CONSTRUCTION PROBLEM 4-41. will prevent frost heave. Determine the floor classification. Determine the minimum compressive strength from Table 4-10. Material such as silts and very fine sand expands under frost action if groundwater is present. The slab thickness design procedure is now complete. SLAB CONSTRUCTION 4-40. The maximum-size aggregate will be 1 inch. and with the accumulated information you should proceed to the mix design procedure as detailed in Chapter 3 of this manual. q Always keep the slab moist and protect it from excessive heat and freezing for the required curing time. Slab construction is often spoiled by improper construction practices that can be easily prevented. Removing these types of soil and replacing them with a free-draining material (gravel or coarse sand) to one-half of the expected frost penetration. Step 7. (in addition to providing adequate drainage at the edges of the structure).25 x 7. This will ensure the concrete is cured properly. Determine the allowable flexural tensile stress. Welded-wire mesh is very desirable for preventing excessive cracking and preventing widening of cracks that do develop. Round up to the next 1/4 inch. q Always use some form of steel reinforcement. depending upon the maximum size of CA to be used.500 pounds and the loaded area equals 40 square inches.25) x SL = 1. Step 1.500 = 9375 lbs Step 5. 4-42. Step 2. Determine the slab thickness for the floor of a wheeled-vehicle shop. Forms for slabs on grades are relatively simple to construct. See Section III of this chapter. Step 3. The following practices should always be employed for ensuring that the slab will hold up under service load. ESL = (1 +. The total weight on one wheel is 7. Step 4. Table 4-9. Abrasive wear is expected. see Class 5. Determine the ESL. Evaluate and correct the ESL if f 't ≠ 300 psi 4-33 .FM 5-428 Chptr 4 Form Design and Construction between the slanted slab thickness lines on the figure.
The minimum cement content per cubic yard from. Determine the slab thickness from Figure 4-6. the thickness is rounded up to 6 3/4-inches. Table 4-11. Loaded area = 40 sq in Slab thickness = 6. 4-42. Therefore. the air content may be less than the table allowance. Minimum cement contents and percentages of entrained air Maximum Size of Coarse Aggregate Minimum Cement Content.500 psi Slab thickness = 6 3/4 inches Minimum cement content = 520 lb/cu yd Air content = 6% Table 4-11. Shown in Percentage* 5+1 6+1 6+1 7 1/2 + 1 7 1/2 + 1 1 1/2 1 3/4 1/2 3/8 4-34 . with 1-inch maximum-size aggregate (MSA) is 520 pounds.FM 5-428 Chptr 4 Form Design and Construction Step 6. in Pounds per Cubic Yard 470 520 540 590 610 Air Content for Freeze-Thaw Resistance.6 in NOTE: Always round up to the next higher 1/4-inch thickness for convenience. Because the structure is a vehicle-shop floor. The slab design information is now: f 'c = 4.
The standard materials for column forms are 2 by 4s and 1-inch sheathing. For structural slabs. Step 3. Step 4. You can obtain all subsequent yoke spacing by reading up this column to the top. Determine the largest cross-sectional column dimension. *Smaller percentages of entrained air can be used for concrete floors that will not be exposed to freezing and thawing or deicing. Step 1. the requirements of ACI 318 and the contract document must be met. Determine the materials you will use for sheathing. The center-to-center spacing between the second yoke and the base yoke is the lowest value in the interval that falls partly in the correct column height line. Adjust final spacing to be at the top of the column. Then move right horizontally to the column heading of the largest cross-sectional dimension in inches of the column you are constructing. COLUMN FORM DESIGN 4-43. Determine the maximum yoke spacing by referring to Table 4-12. and battens. yokes. This may improve the workability of the concrete and the finish product. different mixtures may be needed for lightweight aggregate concrete. First. Table 4-12. Determine the column height. you can place yokes closer together. find the column height in feet in the first column. Step 2. These are maximum yoke spacing. Column yoke spacing using 2 by 4s and 1-inch cheathing 4-35 . Use the following steps in determining design procedures of a wood form for a concrete column.FM 5-428 Chptr 4 Form Design and Construction NOTES: These mixtures are specially for concrete made with normal-weight aggregate.
FM 5-428 Chptr 4 Form Design and Construction 4-36 .
17. 9 feet Step 3. 11. 15. The portion of a structure that extends above the ground level is called the superstructure. Determine the largest cross-sectional dimension. and pier footings are called foundation forms. it is easier to erect the four sides of the form in panels. Use 2-inch dressed lumber for the cleats and space them 2 1/2 inches from each end of the exterior sides of the (a) panels and on 2-foot centers between the ends. Therefore. 17. Whenever possible. Adjust the final spacing to be at the top of the column. CONSTRUCTION FOUNDATION FORMS 4-45. Footings are installed at the base of the foundations to spread the loads over a larger ground area to prevent the structure from sinking into the ground. Determine column height. the yokes are: 8. refer to Table 4-12. it is generally not necessary to base a form design on strength and rigidity. you must construct a form. Determine the maximum yoke spacing. SIMPLE FOUNDATION FORMS 4-46. Determine the yoke spacing for a 9-foot column whose largest cross-sectional dimension is 36 inches. The parts of the substructure that distribute building loads to the ground are called foundations. Because most footings are rectangular or square. and 10-inches. Solution Steps: Step 1. 10. 4-37 . SECTION III. Forms for large footings such as bearing wall footings. Nail vertical cleats to the exterior sides of the sheathing. Thoroughly moisten the earth before placing the concrete. 36 inches Step 4 and Step 5. column footings. Build the first pair of opposing panels (see [a] in Figure 4-7 to the footing width. If this is not possible. The portion below ground level is called the substructure. Footings or foundations are relatively low in height since their primary function is to distribute building loads. Use forming nails driving them only part way for easy removal of the forms. pressure on the form is relatively low. excavate the earth and use it as a mold for concrete footings. The spacing between the top two yokes are reduced due to the limits of the column height.FM 5-428 Chptr 4 Form Design and Construction SAMPLE COLUMN FORM DESIGN PROBLEM 4-44. 8. Lay out materials available. The following steps and figures helps explain this process: Step 1. 2 x 4s and 1-inch sheathing Step 2. Starting from the base. 12. Because the concrete in a footing is shallow. Construction materials are 2 by 4s and 1-inch sheathing.
by 6-inch tie braces nailed across the top of the form keep it from spreading apart. and hold them in place with form nails. you can construct the form from 1-inch sheathing without cleats. Typical foundation Step 2. Step 3. spaced on 2-foot centers. The space between them should equal the footing length. drive stakes against the sheathing as shown in Figure 4-7. For forms 4 feet square or larger. Make sure all reinforcing bars are in place. Erect the panels into either a rectangle or a square. Simply make the side panels higher than the footing depth. 4-38 . plus twice the sheathing thickness. Cut and nail the lumber for the sides of the form as shown in Figure 4-8. Mark the top of the footing on the interior side of the panels with grade nails. and mark the top of the footing on the interior sides of the panels with grade nails. If a footing is less than 1 foot deep and 2 feet square. Step 4.FM 5-428 Chptr 4 Form Design and Construction Figure 4-7. Pass number 8 or number 9 black annealed iron wire through these holes and wrap it around the center cleats of opposing panels to hold them together as shown in Figure 4-7. Nail cleats on the exterior sides of the (b) panels. Drill small holes on each side of the center cleat on each panel less than 1/2 inch in diameter to prevent paste leakage. Both the stakes and the 1. Nail two cleats to the ends of the interior sides of the second pair of panels (see [b] in Figure 4-7).
The form that is build for this type of construction is shown in Figure 4-9 below. This can be accomplished by first nailing 2 by 4s or 4 by 4s across the footing form. Nail the pier form to these support pieces. The footing form should look like the one in Figure 4-7. that serve as both supports and tie braces. 4-39 . You must provide support for the pier form while not interfering with concrete placement in the footing form. It is best to place the footing and a small pier at the same time. that supports the concentrated loads of an arch or bridge super-structure. Small footing form FOUNDATION AND PIER FORMS COMBINED 4-47. A pier is a vertical member.FM 5-428 Chptr 4 Form Design and Construction Figure 4-8. either rectangular or round. as shown in Figure 4-9.
is an exterior wall that serves not only as an enclosure. Stakes hold the sides in place while spreaders maintain the correct distance between them.FM 5-428 Chptr 4 Form Design and Construction Figure 4-9. Footing and pier form BEARING WALL FOOTING 4-48. A bearing wall. The form sides are 2 inch lumber whose width equals the footing depth. also called a load-bearing wall. The short braces at each stake hold the form in line. 4-40 . but also transmits structural loads to the foundation. Figure 4-10 below shows footing formwork for a bearing wall and Figure 4-11 shows bracing methods for a bearing wall footing.
Methods of bracing bering wall footing form COLUMN AND FOOTING FORMS 4-49. Figure 4-2 shows an assembled column and footing form. Place reinforcing steel in columns as described in Chapter 6. Build the column form sides in units first and then nail the yokes to them. Step 3. After constructing the footing form follow the steps below: Step 1. Erect the column form as a unit after assembling the steel reinforcement and tying it to the dowels in the footing. Step 4. Typical footing form Figure 4-11. Be sure to nail the pieces of 4-41 .FM 5-428 Chptr 4 Form Design and Construction Figure 4-10. The column form should have a clean-out hole in the bottom to remove construction debris. Determine the yoke spacing from Table 4-1 according to the procedure described in paragraph 4-43. Square column forms are made from wood whereas round column forms are made from steel or cardboard impregnated with waterproofing compound. Step 2.
When stripping the forms. The sheathing is normally a 1-inch (13/16-inch dressed) tongue-and-groove lumber or 3/4-inch plywood. Then connect the panels as shown in Figure 4-12 below.FM 5-428 Chptr 4 Form Design and Construction lumber that you remove for the clean-out hole to the form. Make the panels by first nailing the sheathing to the studs. Make the wall form shorter than the clear distance between the column forms to allow for a wood strip that acts as a wedge. PANEL-WALL FORMS 4-50. This way you can replace them exactly before placing concrete in the column. It is built only strong enough to carry its own weight and withstand wind pressure on its exterior face. Figure 4-13 below shows the form details at the wall corner. When placing concrete panel-walls and columns at the same time. PANEL-WALL UNITS 4-51. Detail at corner of panel wall form 4-42 . A panel wall is an exterior or curtain wall made up of a number of units that enclose a structure below the roof line. remove the wedge first to facilitate form removal. Figure 4-12. construct the wall form as shown in Figure 4-14. Panel-wall units should be constructed in lengths of about 10 feet for easy handling. Method of connecting panel wall unit form together Figure 4-13.
Use the following steps to install them: 4-43 . Tie wires or tie-rods hold the sides firmly in place so that the weight of the freshly placed concrete does not push them apart. Spreaders keep the sides of the wall form at the proper distance from each other until you place the concrete. Figures 4-15 and 4-16 below show the installation of tie wires and tie-rods. Form for panel walls and columns SPREADERS AND TIES 4-52.FM 5-428 Chptr 4 Form Design and Construction Figure 4-14.
tie-rod and spreader for wall form Step 1. Detail at corner of panel wall form Figure 4-16.FM 5-428 Chptr 4 Form Design and Construction Figure 4-15. Use tie wires (see Figure 4-15 above) only for low walls or when tie-rods are not 4-44 .
Number 8 or number 9 black annealed iron wire is recommended. Form each tie by looping a wire around the wale on one form side. Removing wood spreader Step 6. it through the form and looping it around the wale on the opposite form side. Use pull wires to remove the spreaders as you fill the form so that they are not embedded in the concrete. Loop a wire around the bottom spreader and pass it through off-center holes drilled in each succeeding spreader. 4-45 . Step 2. but you can use barbwire in an emergency. Space spreaders as shown in Figure 4-17 the same as studs. When using the wedge method shown in view 1 of Figure 4-15. as shown in view 2 of Figure 4-15. bringing. Figure 4-17. Space the individual ties the same as the stud spacing but never more than 3 feet apart.FM 5-428 Chptr 4 Form Design and Construction available. Step 3. Figure 4-17 below shows an easy way to remove spreaders. Use tie-rods if rust stains are unacceptable or if the wall units must be held in an exact position. Place a spreader near the location of each tie wire or tie-rod. Step 4. Step 7. Step 5. Remove the nail and drive the wedge until it draws the wire taunt. After stripping the form. twist the ends of the wire strands around a nail driven part way into the point of a wedge. Pull on the wire to remove one spreader after another as the concrete level rises in the form. Make the wire taut by inserting a nail between the two strands and twisting.
7. set the form true to line. When possible. and 12 inches. They contain the concrete and provide a traction surface for form-riding equipment. The usual base plate width is 8 inches. Locking plates rigidly join the end sections. 8. use standard steel pavement forms that can be set fast and accurately. For a better appearance. can be used.FM 5-428 Chptr 4 Form Design and Construction break off the rod at the notch located slightly inside the concrete surface. These steel plate sections are 10 feet long and are normally available in slab thicknesses of 6. Figure 4-18. Make the sloping wood platform that serves as the form for the underside of the steps from 1-inch tongue-and groove-sheathing. Oil the forms immediately after setting them and before depositing the concrete. grout in the tie-rod holes with a mortar mix. After driving the stakes. Space the 2 by 6 cleats nailed to the post supports on 4-foot centers. The platform should extend about 12 inches beyond each side of the stairs to support the stringer bracing blocks. Support the back of the platform with 4 by 4 posts. 10. them grade and clamp it to the stakes using special splines and wedges. Figure 4-18 below shows one way to construct forms for stair widths up to and including 3 feet. After oiling the form completely. Cut the 2 by 12 planks for the side stringers to fit the tread and risers. The post supports should rest on wedges for easy adjustment and removal. including prefabricated ones. Set the forms on the subgrade ahead of the paver and leave them in place for at least 24 hours after placing the concrete. 9. Various types of stair forms. Stairway form STEEL PAVEMENT FORMS 4-54. Bevel the 2 by 12 risers as shown. STAIR FORMS 4-53. Three 1-inch diameter steel stakes per 10-foot section of form are required. A design based on strength is not necessary for moderate-width stairs joining typical floors. wipe the top side or traction 4-46 .
spray. then clean. varnish. On plywood. 4-47 . and stack them in neat piles ready for reuse. Forms should be clean and have smooth surfaces. treat the form surfaces with whitewash or limewater before applying the form oil or other coating. Remove all excess oil.FM 5-428 Chptr 4 Form Design and Construction edge free from oil. Several commercial lacquers and similar products are also available for this purpose. Therefore. and boiled linseed oil are also suitable coatings for forms. or hinder the proper functioning of sealing compounds used for curing. do not clean forms with wire brushes which can mar their surfaces and cause concrete to stick. Plain fuel oil is too thin to use during warm weather. not oils intended for wood forms. treat the forms with a suitable oil or other coating material to prevent the concrete from sticking to them. You can oil all other steel forms when convenient but before reinforcing steel is in place. wet the forms to prevent sticking. Remove the forms as soon as practical. OIL FOR WOOD FORMS 4-56. Oil steel column and wall forms before erecting them. OTHER COATING MATERIALS 4-59. but do not allow the oil or coating to contact construction joint surfaces or any reinforcing steel in the formwork. shellac works better than oil in preventing moisture from raising the grain and detracting from the finished concrete surface. If standard form oil or other form coating is not obtainable. Make sure that any oil or other form coating that is used on forms does not soften or stain the concrete surface. Synthetic castor oil and some marine engine oils are typical examples of compound oils that give good results on steel forms. APPLYING OIL 4-58. oil. Use specially compounded petroleum oils. Apply the oil or coating with a brush. A coat of paint or sealing compound helps to preserve the wood if you plan to reuse wood forms repeatedly. OILING AND WETTING FORMS 4-55. To prevent this condition. making it environmentally safe. OILFOR STEEL FORMS 4-57. The oil should penetrate the wood and prevent water absorption. Use water only in a emergency. asphalt paint. or swab. Fuel oil. Cover the form surfaces evenly. but mixing one part petroleum grease to three parts of fuel oil provides enough thickness. Almost any light-bodied petroleum oil meets these specifications. Sometimes lumber contains enough tannin or other organic substance to soften the surface concrete. prevent the wet surfaces from water curing. The successful use of form oil depends on the method of application and the condition of the forms. Before placing concrete in wood forms.
q Failure to tighten or secure form ties. q Observe the weather. many form failures occur because of some human error or improper supervision. Observe the following safety precautions during construction: q Inspect tools frequently--particularly hammers. q Failure to sufficiently allow for eccentric loading due to placement sequences. FORMS STRIPPING 4-62. Observe of the following safety precaution when stripping forms: q Permit only those workers actually stripping forms in the immediate work area. Protruding nails are the main source of formwork accidents. q Pile stripped forms immediately to avoid congestion. q Use of old. Do not remove forms until the concrete sets. Safety precaution should be practiced at all times. q Brace all shoring to prevent possible formwork collapse. OVERHEAD SLAB FAILURES 4-65. take precautions to protect both workers on scaffolds and ground personnel. q Failure to allow for lateral pressures and forces. q Failure to sufficiently nail members. Even when all formwork is adequately designed. exposed nails. or weathered form materials. WALL-FORM FAILURES 4-64. damaged. q Place mudsills under shoring that rests on the ground. and other hazards. Section XI. q Take caution when cutting wires under tension to avoid backlash. The following items are the most common construction deficiencies in wall-form failures and should be considered by supervisory personnel when working with concrete: q Failure to control the rate of placing concrete vertically without regard to drop in temperature. FORM CONSTRUCTION 4-61. q Use of undersized form material. When work is progressing on elevated forms. FORM FAILURE 4-63. See Chapter 5.FM 5-428 Chptr 4 Form Design and Construction SAFETY PRECAUTIONS 4-60. The Following Are common Construction Deficiencies In Overhead slab Failure: 4-48 . do not attempt to raise large form panels in heavy wind gusts. either by hand or by crane.
power buggies. Failure to sufficiently allow for eccentric loading due to placement sequence. Failure to plumb shoring thus inducing lateral loading as well as reducing vertical load capacity. Concrete structures are subjected to internal and external stresses caused by volume shrinkage during hydration.FM 5-428 Chptr 4 Form Design and Construction q q q q q q q q q q Failure to adequately diagonally brace the shores. there are many reasons why forms fail. q Lack of proper supervision and field inspection. OTHER GENERAL CAUSES OF FAILURE 4-66. The following are miscellaneous causes of form failure: q Failure to inspect formwork during and after concrete placement to detect abnormal deflections or other signs of imminent failure which could be corrected. Failure to provide adequate reshoring. These stresses can cause cracking. JOINTS AND ANCHORS JOINTS 4-68. It is the responsibility of the form designer to ensure that the concrete will not fail when the designs are properly interpreted and constructed. Failure to correct deficiencies where locking devices on metal shoring are not locked. Failure to prevent vibration from adjacent moving loads or load carriers. and scaling of concrete surfaces and in extreme cases result in failure of the concrete structure. Failure to allow for lateral pressures on formwork. inoperative. or missing. 4-67. q Failure to ensure adequate anchorage against uplift due to battered form faces. An example would be the joint that separates the floor slab from a column (to allow for differential movement in the vertical plane due to loading conditions or uneven settlement). differential movement due to temperature changes. and differential movement caused by different loading conditions. ISOLATION JOINTS 4-69. Three basic types of joints will be addressed--the isolation joint. It is the responsibility of the builder to make sure that the design is correctly constructed and that proper techniques are followed. Failure to stabilize soil under mudsills. Lack of allowance in design for such special loads as winds. the control joint. SECTION IV. These stresses can be controlled by the proper placement of joints in the structure. and the construction joint. or placing equipment. This list is not all inclusive. q Failure to prevent form damage in excavated area caused by embankment failure. Isolation joints are used to separate or isolate adjacent structural members. Isolation joints are 4-49 . Failure to prevent premature removal of supports especially under long continuous sections.
4-20. All isolation joints extend completely through the member and do not have any load transfer devices built into them. See Figures 4-19. Typical isolation and control joints 4-50 . Figure 4-19.FM 5-428 Chptr 4 Form Design and Construction sometimes referred to as expansion or contraction joints to allow for differential movement as a result of temperature changes (as in two adjacent slabs). and 4-21 below.
Expansion/contraction joint for a bridge CONTROL JOINTS 4-51 .FM 5-428 Chptr 4 Form Design and Construction Figure 4-20. Joints at colums and walls Figure 4-21.
in Feet in Feet 4-52 . If the slab is restrained from curling. driveways. Control joints (see Figure 4-22 below) are cut into the concrete slab to create a plane of weakness that forces cracking (if it happens) to occur at a designated place rather than randomly. In a slab the shrinkage occurs more rapidly at the exposed surfaces and causes upward curling at the edges. Control joints in interior slabs are typically cut 1/3 to 1/4. Temperature steel (welded wire fabric) may be used to restrict crack width for sidewalks. Figure 4-22. of the slab thickness and then filled with lead or joint filler. the joint should be 3/4 to 1-in deep. Surface irregularities along the plane of the cracks are usually sufficient to transfer loads across the joint in slabs on grade. Spacing of Control joints Slab Less Than Larger Slump Thickness.FM 5-428 Chptr 4 Form Design and Construction 4-70. and tooled joints spaced at intervals equal to the width of the slab but not more than 20 ft (6 meters) apart. cracking will occur wherever the restraint imposes stress greater than the tensile strength. see Table 4-13 for suggested control joint spacing. Spacing. Movement in the plane of a concrete slab is caused by drying shrinkage and thermal contraction. Aggregate Inches in Feet Spacing. These joints run in both directions at right angles to each other. 3/4 inch Than 3/4 Less in Inches Aggregate inch Than 4 Spacing. Some shrinkage is expected and can be tolerated depending on the design and exposure of the particular structural elements. Control joint Table 4-13.
Note that the construction joint extends entirely through the concrete element. Figure 4-23. CONSTRUCTION JOINTS 4-71. Keyed.FM 5-428 Chptr 4 Form Design and Construction 5 6 7 8 9 10 10* 12 14 16 18 20 13 15 18 20 23 25 15 18 21 24 27 30 NOTE: Spacing also applies to the distances from the control joints to the parallel isolation joints or to the parallel construction joints. wall construction joint (perspective view) 4-53 . These joints allow some load to be transferred from one structural element to another through the use of keys or (for some slabs and pavement) dowels. Construction joints (see Figures 4-23 through 4-26 below) are made where the concrete placement operations end for the day or where one structural element will be cast against previously placed concrete.
FM 5-428 Chptr 4 Form Design and Construction Figure 4-24. Keyed. Construction joint between wall and footing showing keyway 4-54 . wall construction joint (plan view) Figure 4-25.
The diameter of the sleeve should be at least 1 inch larger than the bolt.FM 5-428 Chptr 4 Form Design and Construction Figure 4-26. 4-55 . Instead set the anchor bolts in the floor so they extend above the base. The anchor bolt (see Figure 4-27 below) is used to anchor either machinery or structural steel. Do not use the sleeve if machinery mounts are on a raised base that is 4 or more inches above the floor. The sleeve allows the bolt to shift to compensate for any small positioning error. Finally pour the base by packing the concrete into place from the sides. The pipe sleeves are packed with grease to keep concrete out during paving operations. Types of construction joints ANCHOR BOLTS 4-72. Place the machine--blocked up on scrap steel and leveled--and tighten the anchor bolts.
Make the bolt holes in the board 1/16 inches larger than the bolt to permit adjustment.FM 5-428 Chptr 4 Form Design and Construction Figure 4-27. Anchor bolt with pipe sleeve THE HOOKED ANCHOR BOLT AND THE SUSPENDED ANCHOR BOLT 4-73. The hooked anchor bolt (see Figure 4-28) and the suspended anchor bolt (see Figure 4-29 below) are both used to fasten a wood sill to either a concrete or masonry wall. Hooked anchor bolt 4-56 . Be careful not to disturb suspended bolt alignment when placing the concrete. Figure 4-28.
Anchor bolts held in place by a templet 4-57 . (See Figure 4-30). Suspended anchor bolt A TEMPLET 4-74.FM 5-428 Chptr 4 Form Design and Construction Figure 4-29. A templet is used to hold anchor bolts in place while placing concrete. Figure 4-30. When using sleeves in a templet adjust them so that the top of the sleeve is level with the top of the finished concrete.
the quality of existing roads and bridges. q Water and aggregate location. q Establishing the location of the batch plants. Mixing. Reconnaissance is primarily the first step taken for any construction project. Note possible problems in clearing and draining the site and in transporting and storing materials. As concrete is placed in its final location. Initially the concrete should be screeded to the specified elevation. You can avoid construction delays by anticipating and considering such problems beforehand. Special consideration such as the following must be given to any planning procedures: q Route selection. Specific consideration should be given to--route selection. such as sprinkling the concrete with water after the initial set and placing plastic over the surface. Investigate the site for any unusual characteristics that can cause construction problems such as undesirable soil or rock base. Local traffic patterns. If a smoother surface is required. Make maximum use of the existing road network. and the equipment used all affect the selection of the best route to the construction site. Select an alternate route when possible. water and aggregate location. handling. Site preparation includes-q Clearing and draining the site. provide effective moisture barriers that enhance the curing process SECTION I. q Stockpiling construction materials. q Establishing the location of the structure. Locate the nearest or most convenient source of suitable mixing water. Curing methods. this will save time and effort by repairing or improving an existing road rather than constructing a new one. and time estimation. RECONNAISSANCE DETERMINING POSSIBLE DIFFICULTIES 5-2. this may be accomplished by floating with a steel trowel.FM 5-428 Chptr 5 Construction Procedures Chapter 5 Construction Procedures 5-1. various finishing operations may be done. The first step in any construction procedure is to make a thorough and efficient reconnaissance of the construction site. Note any alternate sources in case subsequent tests show that your first 5-1 . The types and amounts of excavation must be planned for equipment utilization and availability. SPECIFIC CONSIDERATIONS 5-3. and transporting must be strictly followed to maintain quality control measures.
Although these are temporary roads. STOCKPILING CONSTRUCTION MATERIALS 5-8. construct them carefully to withstand heavy loads.FM 5-428 Chptr 5 Construction Procedures q choice is unsuitable. use local sand and gravel sources. and disposing of all materials cleared. This assures the proper equipment is available at both the place and time of need SECTION II. Time estimation. Use either a well-point system or mechanical pumps to withdraw surface and subsurface water from the building site. LOCATING THE BUILDING SITE 5-7. CONCRETE MATERIALS 5-2 . Heavy equipment. The batter-board layout is satisfactory in the preliminary construction phases. Drainage is important in areas having high groundwater tables and for carrying off rainwater during actual construction. This method consists of placing batter boards about 2 to 6 feet outside of each corner of the site. Whenever possible. downed timber. Therefore. Stake out the building site after clearing and draining the land. the approach roads need building up to deliver materials to the site. and other vegetation and rubbish from the site to include the remains of previous construction efforts. SITE PREPARATION BUILDING APPROACH ROADS 5-4. digging up surface boulders and other materials embedded in the ground. q The time available until completion. q The terrain affect upon equipment operations. ENSURING ADEQUATE DRAINAGE 5-6. q The availability of equipment and personnel. Build enough lanes to permit free traffic flow to and from the construction site because the routes may become permanent roads later. and burning by fire may all be needed to clear the site of large timbers and boulders. q The type and density of vegetation. driving nails into the boards. explosives. Locate these sources and specify any necessary tests. Land clearing consists of removing all trees. CLEARING AND DRAINING THE SITE 5-5. Estimate the time for site preparation carefully during reconnaissance. It is important to build up and maintain stockpiles of aggregate both at the batching plant and at the crushing and screening plant. brush. and extending strings between them to outline the building area. The methods to be used depends on-q The acreage to be cleared. hand equipment. Most new construction takes place on undeveloped land.
make sure that enough are on hand. Large stockpiles are usually rectangular for ease in computing volumes. require additional safety facilities SECTION III. They are flat on top to retain gradation uniformity and to avoid segregation caused by dumping aggregate so that it runs downs a long slope. the physical characteristics of the soil. drained. enough cement must be maintained at the cement-batching plant. The size and quantity of lumber stored depends on the type of forms and/or scaffolding used. LUMBER AT CONSTRUCTION SITE 5-10. because it is difficult to compact the fill surface properly. Plan and construct the safety facilities during site preparation. Both aggregate and cement batching plants are essential in operations requiring large quantities of concrete. The batching-plant stockpiles prevent shortages caused by temporary production or transportation difficulties that allows the FA to reach a fairly stable and uniform moisture content and bulking factor. Sandy soils and wet earth generally require 5-3 . place the concrete to the actual excavation depth. If admixtures are used. and outlined. it can be operated at the batching plant or at a separate location. When the building site is cleared. The type of shoring varies with the depth and size of the excavation. Attempts to refill an excavation to the depth specified are not recommended unless an elephant-foot tamper is used to properly compact the fill. EXCAVATION EXCAVATION AND SHORING CONSIDERATIONS 5-13. The initial location of the aggregate. This may eliminate the need for cranes or conveyors if the road is good. Stockpile plenty of formwork and scaffolding materials at the construction site. and the location of the work all affect where the cement batching plant is positioned. Good engineering practice dictates using shoring whenever slope stability is questionable.FM 5-428 Chptr 5 Construction Procedures 5-9. The amount of concrete required by the project and the placement rate determine the size of the stockpiles. cut the land to the proper elevation for placing footings. After developing a layout. Use suitable equipment for the initial excavation. LOCATING BATCHING PLANTS 5-11. Even if you excavate too much earth. Some type of lateral provides support for both safety and economy whenever excavation is at such a depth that the slopes become unstable. A hillside location permits gravity handling of materials without excessive new construction. and the fluid pressure under saturated conditions. and water. CONSTRUCTING SAFETY FACILITIES 5-12. This includes overhead canopies and guardrails both to protect personnel from falling debris and to prevent anyone from falling into open excavations. you can operate it at the same place as the aggregate batching plant or closer to the mixer. The excavation should extend beyond the exterior wall edges to allow for placing forms and applying waterproofing material. cement. the aggregate quality. but excavate to the final depths by hand. position the batching plant within crane reach of the aggregate stockpiles and astride the batch truck routes. Although the crushing and screening plant is normally located at the pit. Depending on these conditions. Certain sites. such as those where landslides may occur.
The most suitable types of equipment include power shovels. it is extremely difficult to excavate that closely with a machine. MACHINE EXCAVATION 5-14. q The nature of the area.FM 5-428 Chptr 5 Construction Procedures more extensive shoring than firmer soils. Machine excavation Equipment Type of Material Average Output. q The working time available. Due to the many variables. and a backhoe. However. q The type of excavation. Clear out and shape the last 6 inches of bottom excavation by hand. Table 5-2 gives hand excavation rates which vary with soil types and excavation depth. Table 5-1 gives some typical rates of excavation for specific conditions that still will vary considerably in practice. Machines are a necessity for large projects requiring substantial excavation. Table 5-2. dragline buckets. Table 5-1. Hand excavation Types of Material Average Output Yards Per Hour 5-4 . When selecting equipment consider: q The total yardage to be move. it is not possible to give generalized rates of excavation for various types of equipment. in Cubic Yards per Hour 70 60 45 25 65 50 40 20 55 45 35 25 Power shovel (1/2 cu yd capacity) Sandy loam Common earth Hard clay Wet clay Short-boom dragline Sandy loam (1/2 cu yd capacity) Common earth Hard clay Wet clay Backhoe (1/2 cu yd capacity) Sandy loam Common earth Hard clay Wet clay Hand Excavation 5-15.
These tools should be readily available.5 . It is important to be knowledgeable of-q Equipment.FM 5-428 Chptr 5 Construction Procedures Excavation With Pick and Shovel to Depth Indicated 0 to 3 ft 0 to 6 ft 0 to 8 ft 0 to 10 ft Loosening Loading in Earth-One Trucks or Worker WagonsWith Pick One Worker With Shovel. TIME ELEMENT 5-17. plumb lines. table saws.4 1. To perform a proper analysis.4 1.6 .0 1.2 . q Techniques.4 . such as those for stairways.3 1.3 SECTION IV. and carpenter's squares. This saves time and material.6 1.9 1. increased man power support at the ground level increases efficiency SECTION V.7 1.1 1. and stripping forms to the maximum extent possible.2 .5 1.7 Sand Silty sand Loose gravel Sandy silt-clay Light clay Dry clay Wet clay Hardpan 2.3 1. you must have a working knowledge of the equipment necessary for the form work job and a good idea of how much work the form builders can turn out per unit of time.5 .4 1.5 .4 1. erecting.2 1. levels.9 .2 1.0 1.6 . MIXING 5-5 . portable electric saws.7 .2 1.7 1. Some forms. A carpenter of average skill can build and erect 10 square feet of wood forms per hour. require considerable physical support from underneath. This figure increases as the worker becomes more skilled in form construction.9 .4 . pinch bars. Break large projects into smaller.4 1. and simplifies design problems.8 1. The average form work job requires claw hammers. It also varies with the tools and materials available and the type of form.0 4.4 1. Develop standardized methods for constructing. Some forms take more man-hours and materials to build than simpler forms.0 . For carpenters to move from one level to another frequently requires additional time. Therefore.6 .0 .0 1.4 .8 2.3 1. FORM WORK MANAGEMENT ASPECTS 5-16.4 1. hand saws. Loose Soil 6.7 .9 1.7 2. nearly identical units.
you can use platform scales placed on the ground to weigh aggregate. However. Measure mixing water accurately for every batch.Measurement by volume. wheelbarrows. Established and well-defined concrete-mixing procedures must be followed to produce good quality finished concrete. Construct runways as shown in Figure 5-1. cubic feet.Measurement by weight. as well as for larger batches. Do not load a wheelbarrow to capacity. q Aggregate. Measure aggregate by volume using a 1-cubic foot measurement box built on-site or a wheelbarrow. Whoever is in charge of construction must know the concrete-mixing procedures and ensure that they are followed. sacked cement is used almost exclusively in troop construction. regardless of the units of measure used (shovels. On comparatively small jobs. . particularly in the theater of operations. Bulk cement is stored in bins directly above a weighing cement hopper and discharged from the hopper. Never become overconfident in this phase of concrete construction. Periodically check equipment for accuracy and adjust when necessary. Water. Nevertheless.FM 5-428 Chptr 5 Construction Procedures PRINCIPLES 5-18. A simple way to mix batches is the 1:2:3 method. Measure aggregate for each batch accurately either by weight or by volume. If the aggregate contains too much moisture. Always place the same weight of aggregate on each wheelbarrow so that the quantity per batch equals the same number of wheelbarrow loads. Concrete mixes normally call for sacked cement as the unit of measure. and so forth). you can fill a wheelbarrow so accurately that adding or removing material to obtain the correct weight is seldom necessary. water. and 3 parts aggregate. MEASURING MIX MATERIALS 5-19. be sure to take this into account when adding mixing water. 1 percent. aggregate. and admixtures. The water tanks on machine mixers often have automatic measuring devices that operate like a q 5-6 . With practice. Check admixture dispensers daily for errors in admixture measurements--particularly over-dosages. Always measure the following: q Cement. This means that each batch contains 1 part cement. Concrete of uniform quality requires measuring the ingredients accurately for each batch within these percentages: cement. 1 percent. so that a wheelbarrow can run onto one side of the scale and off the other easily. . Measurement by weight is the most reliable because the accuracy of volume measurement depends on an exact knowledge of the amount of moisture in the sand. because bulk cement requires special equipment for transport. 2 percent. Wheelbarrows having from 2 to 3-cubic feet capacity are also available in the engineering units. sometimes measurement by volume is more practical. this can cause serious problems in both fresh and hardened concrete. whether caused by lack of competent and conscientious supervision or inattention to detail. The extra effort and care this requires are small in relation to the benefits in terms of strength consistency and finished appearance. 3 percent. Equipment should be capable of measuring quantities within these tolerances for the smallest batch used. 2 parts sand. although bulk cement is common practice in commercial construction requiring large quantities.
hand mixing sometimes may be necessary. Use either a hoe (see the middle of Figure 5-2) or a square-pointed D-handled shovel to mix the materials. You can also mix in a hoe box shown at the bottom of Figure 5-2. Figure 5-1. 5-7 . Instead. Although one worker can mix 1 cubic yard of concrete by hand in about 1 hour. even. this is not economical for batches of more than 1 cubic yard. A clean surface is needed for this purpose. Although a machine generally does the mixing. paved surface or a wood platform having tight joints to prevent paste loss like the one shown at the top of Figure 5-2 below. or until you obtain the proper consistency. two workers facing each other should work their way through the pile. Turn the dry materials at least three times until the color of the mixture is uniform. Moisten the surface and level the platform. Measuring aggregate by weight HAND MIXING 5-20. and then spread the CA over the cement as shown at the top of Figure 5-2. such as a clean. Add water slowly while you turn the mixture again at least three times. and keep their shovels close to the platform surface while turning the materials. spread cement over the sand.FM 5-428 Chptr 5 Construction Procedures siphon.
Power-concrete mixers normally produce one batch about every 3 minutes including charging and discharging. and are well-suited for troop construction projects. The methods of mixing and delivering concrete ingredients and the types and sizes of equipment available vary greatly. Most mixers can handle a 10 percent overload. Actual hourly output varies from 10 to 20 batches per hour. Figure 5-3.FM 5-428 Chptr 5 Construction Procedures Figure 5-2. M919 Concrete Mobile Mixer 5-8 . Hand mixing of concrete MACHINE MIXING AND DELIVERY 5-21. A mixer's cubic foot rating usually reflects the number of cubic feet of usable concrete that the machine mixes in one batch. The stationary 16-cubic-feet mixer and the M919 Concrete-Mobile-Mixer unit (see Figure 5-3) are table of organization and equipment (TOE) equipment in engineer construction battalions.
Be especially careful to avoid segregation when using dump trucks. pump. On a concrete wall project move the mixer to each wall in sequence to reduce transportation distance and time. Method used for mixing and delivering "dry-batched" ready-mix by truck. Method used for delivering plastic concrete by chute. are available in various sizes. SITE MIX PLANTS 5-25. Truck mixers generally deliver concrete from a centrally located stationary mixer to the construction site or pick up materials at a batching plant and mix the concrete enroute to the job site. q Central-plant mixed. Trailer-mounted mixers are commonly used to patch concrete pavements and to form and widen curve during pavement con-struction. conveyor. q Portable-mixing plant mixed. A battery of trailer-mounted mixers can serve either as a central mix plant for large scale operations or in conjunction with a central mix plant. q Central-plant batched (weighed and measured). revolving blades or paddles. They may be tilting or nontilting with open top. or rail dump cars. q Mobile mixers include both truck -and trailer-mounted mixers. but you must take special precautions to make sure that the concrete has the proper characteristics and workability upon arrival at the work site. CENTRAL MIX PLANTS 5-24. A clamshell bucket crane. The proper location of mixing equipment and materials at the site can yield large savings in time and labor. Either stationary mixers or a battery of trailer-mounted mixers usually makes up a central-mix plant which is normally a gravity-feed operation. truck. Mixing methods include-q Site mixed. Mixing time and mixing requirements do not differ much from those already discussed.FM 5-428 Chptr 5 Construction Procedures MIXING METHODS 5-22. Mixer types include-q Stationary mixers. A truck mixer may pick up concrete from the stationary mixer in a partially or completely mixed state. Method used for delivering plastic ready-mix in either open dump trucks or mixer trucks. or elevators carry materials to a batching plant set high enough to discharge directly into dump trucks or other distribution equipment. Always locate the mixer as close to the main section of the pour as possible. conveyor belts. Method used for large building or paving projects distant from sources of supply. 5-9 . which include both the on-site mixers and the central mixers in the ready-mix plants. Figure 5-4 below shows a typical on-site arrangement of mixer and materials. the truck mixer functions as an agitator. In the latter case. MIXER TYPES 5-23.
and water. The location of the mixing water depends on the type of water supply available. The crew operates the mixer and handles the aggregate. If you are using a water truck or trailer. who must be competent. The noncommissioned officer. use a hose to carry it to a barrel near the mixer. Normal operation of the mixer requires ten soldiers and one noncommissioned officer.FM 5-428 Chptr 5 Construction Procedures Figure 5-4. park it next to the mixer. Table 5-3. and the mixer's discharge rate. OPERATING THE 16-CUBIC FOOT MIXER 5-26. supervises the overall operation. If water is piped in. Physical characteristics of a typical 16-cubic feet mixer 5-10 . depending on their experience. You would need at least one platoon to operate an overall project like the one in Figure 5-4 above. Table 5-3 below gives the physical characteristics of a typical 16-cubic-feet mixer. the location of materials. Hand mixing of concrete Store aggregate and sand as close to the mixer as possible. without interfering with concrete transportation. cement. The crew should produce about 10 cubic yards of concrete per hour. sand.
FM 5-428 Chptr 5 Construction Procedures Physical Characteristics Drum capacity q Hourly production q Rating. When using the skip. A storage tank on top of the mixer measures the water in the drum a few seconds before the skip dumps. 5-11 . cement. end discharge. deposit the aggregate. and sand (in that order) into the skip and then dump it into the mixer while water runs into the mixing drum. Mixers can be charged in two ways: by hand or with a mechanical skip (see Figure 5-5 below).5 q Width Height (in) none Weight (lb) 26 57 46 158 96 119 7.150 *The mixer is gas driven. liquid cooled. Place the sand on top of the pile in the skip so that you do not lose too much cement as the batch dumps into the mixer. Charging the Mixer 5-27. in sacks per batch Power unit q Horsepower q Fuel consumption (gal/hr) Water tank q Supply q Measurement (gal) Concrete Mixer* Physical Characteristics Concrete Mixer* 16 cu ft Drum Dimensions q Diameter (in) 10 cu yd q Length (in) 2 Overall dimension (in) 26 q Length 0. with 4-pneumatic-tired wheels. trailer mounted. This discharge also washes down the mixer between batches.
or following each period of use if it operates less than 1 day. To do this. because concrete adheres more readily to dents and bumps. This is normally during the first quarter of the mixing period. requires an additional 15 seconds of mixing time. Knock off all accumulated concrete on the mixer exterior and wash it down with a hose. The mixing time starts when water runs into the dry mixture. Clean it out whenever you shut down for more than 1 1/2 hours. Mixer blades that are worn or coated with hardened concrete provide less efficient mixing action. Clean the mixer daily. The minimum mixing time per batch of concrete is 1 minute unless the batch exceeds 1 cubic yard. diminishing the effectiveness and composition of the concrete. When the mix is ready for discharge from the mixer. The exterior cleaning process goes faster if you coat the outside of the mixer with form oil before you use it. Concrete that is somewhat dry tends to cling to the top of the drum and not drop onto the chute in time. Very wet concrete may not carry up high enough on the drum to drop onto the chute. Correct these problems by adjusting the mixer speed. or fraction thereof. and do not allow hardened concrete to accumulate in the mixer drum. Then discharge the aggregate and flush out the drum with water. Replace badly worn blades. drum shell.FM 5-428 Chptr 5 Construction Procedures Figure 5-5. Each additional cubic yard of concrete. Diligence in cleaning the drum is important because hardened concrete in a mixer absorbs mixing water during subsequent batches. Increase the speed for very wet concrete and decrease the speed for dry concrete. place a volume of CA equal to one-half the mixer capacity in the drum and allow it to revolve for about 5 minutes. Charging a 16 cubic-foot mixer Discharging the Mixer 5-28. 5-12 . Cleaning and Maintaining the Mixer 5-30. or skip to remove aggregate or hardened concrete. Mixing Time 5-29. Never strike the discharge chute. if it operates continuously. move the discharge chute into place to receive the concrete from the drum.
M919 Concrete-Mobile-Mixer unit Physical Characteristics Capacity Hourly production Rating. you can produce mixes that meet or exceed both the ACI and the American Association of State Highway and Transportation Officials (AASHTO) standards for design strength. The unit operates on either an intermittent or continuous basis. Because the unit is precisely calibrated. in sacks per batch Power unit 8 cubic yards 16 cubic yards Varies M915-series Cummins engine powered by power take-off from the truck transmission 400 gallons 63 cubic feet 128 cubic feet 182 cubic feet 42 gallons 12 gallons 2.35 cubic feet Water tank Cement bin Sand bin Gravel bin Hi flow admix tank Lo flow admix tank Dry admix tank Overall Dimensions and Weight Length Width Height Weight (empty) 374 inches 96 inches 142 inches 37. The special body is mounted on a model M919 truck chassis. The Concrete-Mobile-Mixer unit is a combination materials transporter and an on-site mixing plant. although continuous operation depends on raw material availability at the site. The unit carries enough unmixed material to produce up to 8 cubic yards of fresh concrete. Certain control settings for the mix operations vary from truck to truck and from site to site. Table 5-4 below gives its physical characteristics and overall dimensions.FM 5-428 Chptr 5 Construction Procedures OPERATING THE M919 CONCRETE-MOBILE MIXER UNIT 5-31. Table 5-4.540 pounds 5-13 .
When placed in a bucket. When fresh concrete is left standing and not poured. Figure 5-6 shows several right and wrong ways to handle concrete to prevent segregation of the aggregates and paste. To remix a batch. Remixed concrete tends to harden rapidly. REMIXING CONCRETE 5-32. 5-14 . HANDLING AND TRANSPORTING PRINCIPLES 5-33.FM 5-428 Chptr 5 Construction Procedures Use the dials on the rear and sides of the M919 to control concrete mixes by regulating the amount of sand. or maximum allowable mixing and agitating time. Then test the concrete to make sure that it does not exceed the maximum allowable W/C ratio. HANDLING TECHNIQUES 5-34. water. choose equipment that can handle and transport such a mix without affecting its consistency. it tends to stiffen before the cement can hydrate to its initial set. Segregation occurs because concrete contains aggregates of different particle sizes and specific gravities. Do not add water randomly because this lowers concrete quality. the coarser particles tend to settle to the bottom and the water rises to the top. and admixes. Any fresh concrete placed adjacent to or above remixed concrete may cause a cold joint SECTION VI. if placing conditions allow a stiff mix. Such concrete is still usable if remixing makes it sufficiently plastic to be compacted in the forms. Handling and transporting methods can affect its consistency. Concrete consistency depends on the conditions at placement. Segregation causes honeycomb concrete or rock pockets. Therefore. gravel. and remix the concrete for at least one-half of the minimum required mixing time or number of revolutions. carefully add a small amount of water. maximum allowable slump. Carefully control each handling and transporting step to maintain concrete uniformity within a batch and from batch to batch so that the completed work is consistent throughout.
Concrete handling techniques to prevent segregation TRANSPORTATION REQUIREMENTS 5-15 .FM 5-428 Chptr 5 Construction Procedures Figure 5-6.
use a hopper and chute like the ones shown in Figure 5-10 to prevent segregation. such as a bucket and a crane. Organize the transportation to eliminate delays in concrete placement that cause undesirable fill planes or construction joints. q Minimum material segregation. To provide room for the ledger. it is more economical to use elevating equipment. power buggies (see Figure 5-8) are best for longer runs. foundation walls. If possible. View 1 in Figure 5-9 below shows a runway along a wall form that is almost level with the top of the form sheathing. To produce uniform concrete take steps to reduce segregation of the aggregates and paste to a minimum. economically construct inclined runways (see view 2 of Figure 5-9) for buggy or wheelbarrow use. set 2-inch plank runways directly on the ground to permit pouring the concrete directly into the form. or slabs on or below grade. A runway for placing concrete on a floor slab also consists of 2 by 10s supported by 4 by 4s placed on 6-foot centers. Wheelbarrows or buggies (see Figure 5-7) are the most practical and economical to deliver concrete for foundations. SMALL JOBS 5-37. A runway can be made economically from rough lumber consisting of 2 by 10 planks. Concrete delivery equipment must be capable of handling 100 percent of the mixer capacity to meet peak demands. The slope of the chute should normally be 2:1 or steeper for stiff mixes. arrange them so that the buggies or wheelbarrows do not need to pass each other on a runway at any time. If available. Always brace runways securely to prevent failure. cement. Both wheelbarrows and buggies require suitable runways. Fast transportation does not allow concrete to dry out or lose workability or plasticity between mixing and placing. If a large quantity of concrete more than 5 to 6 feet is elevated. 5-16 . DELIVERY METHODS 5-36. Nail the 1 by 6 ledger on the form side to the studs on the wall form. If the difference in elevation from the runway to the bottom of the structure is large.foot centers. This will allows wheeling the concrete up inclined runways having a slope of 10:1. the top wale is at 1 foot below the top of the concrete. Such runways are built from either the formwork or the ground. supported by 4 by 4s. or water. The three main requirements for transporting concrete from the mixing plant to the job site are: q Speed. When placing concrete about 5 to 6 feet above grade. and spaced on 6.FM 5-428 Chptr 5 Construction Procedures 5-35. this will help prevent the loss of fine material. When placing concrete below or at approximate grade. q No delays.
FM 5-428 Chptr 5 Construction Procedures 5-17 .
18 . Runways for wheelbarrow or buggy use 5.FM 5-428 Chptr 5 Construction Procedures Figure 5-9.
5-19 . Timely delivery of enough concrete on large projects requires careful planning and the selection of the right type of equipment for the purpose. Dump trucks 5-39.FM 5-428 Chptr 5 Construction Procedures Figure 5-10. keep hauling distances as short as possible. maintain slow speed. and utilize smooth roads to reduce vibration. Ordinary dump trucks are not designed as concrete carriers although they are commonly used to deliver concrete on large projects in the theater of operations. Exercise care in using them because no means of preventing segregation is provided as it is on mixers or agitator trucks. Hopper and chute for handling concrete LARGE JOBS 5-38. Even if you use a stiff mix and an air-entraining agent to reduce segregation.
or 8-inch pipeline as shown in Figure 5-12. Both machines can pump a mix having 2 or more inches of slump and force their rated capacities up to 800 feet horizontally. When starting the pump. A deflector or choke (restricted section) can be used at the discharge end of the pipeline to direct and control the discharge flow. plastic. Maximum aggregate size is 3 inches for the 8-inch pipeline. unsegregated concrete having medium consistency. You can use either transit-mix or ready-mix trucks as agitator trucks to deliver premixed concrete. ready for placement. and 2 inches for the 6-inch pipeline. The doors or gates are hand operated for flexibility in discharging the bucket. Figure 5-11 shows a crew using a bucket and crane to place concrete.FM 5-428 Chptr 5 Construction Procedures Agitator trucks 5-40. An interrupted flow in the pipeline can seriously delay the concrete pour. 100 feet vertically. However. A transit-mix truck is a concrete truck (M919) where materials are mixed after they arrive on the site. The discharge line should be as straight as possible. A ready-mix truck comes from the batch plant to the site already mixed. q Pumps. Be sure to thoroughly flush both the pump and line with water after each use. The trucks discharge concrete either continuously or intermittently from a spout or chute that moves from side to side. lubricate the pipeline with a light cement grout first. causing undesirable joints in the structure. They are either square or cylindrical with a clamshell door or gate at the bottom. One disadvantage of using pumps is that the concrete mix is usually more expensive due to the smaller aggregate required to pass through the pump. 7-. but the operating radius of the ready-mix trucks is somewhat more limited. Take appropriate steps to cool the pipe in hot weather for smooth concrete flow. or any equivalent combination of these distances. Buckets in 2 yard capacities are standard TOE and Class IV items in combat heavy engineer battalions. 2 1/2 inches for the 7-inch pipeline. and each foot of vertical lift decreases horizontal delivery distance by 8 feet. use a heavy-duty piston pump to force concrete through 6-. 5-20 . resulting in a correspondingly higher requirement for expensive cement. Larger equipment with a double-acting pump has a rated capacity of 50 to 60 cubic yards per hour. Then make sure the pump receives an uninterrupted flow of fresh. Pumps operated by a 25 horsepower (HP) gasoline engine have a rated capacity of 15 to 20 cubic yards per hour. When limited space prevent other more conventional means of delivery. with a 5-foot-radius bend. a 90-degree bend in the pipeline decreases horizontal delivery distance by 40 feet. q Buckets. The load capacity of a ready-mix trucks is 30 to 35 percent greater than transit-mix trucks.
both contributes to the full strength and best appearance. PLACEMENT IMPORTANCE OF PROPER PROCEDURES 5-41. You cannot obtain the full value of well-designed concrete without using proper placing and curing procedures. Good concrete placing and compacting techniques produce a tight bond between the paste and the CA and fills the forms completely. 5-21 . Placing concrete using a bucket and crane Figure 5-12. Piston pump and discharge pipeline SECTION VII.FM 5-428 Chptr 5 Construction Procedures Figure 5-11.
The mortar should have a 6-inch slump. all the concrete required in a project is placed at once in a monolithic placement. moisten the forms with water to prevent concrete from sticking. Remove all water from the depressions and coat the rock surfaces with a 3/4-inch-thick layer of mortar. sand. Compacted sand is not covered. Preparation includes-q Preparing rock surfaces. Check the bracing to make sure the forms will not move during placing. saturate dried-out concrete for several hours. Forms exposed to the sun for some time dry out and the joints tend to open up. see Figure 4-2. The size of each day's placement is planned based on where construction joints can be placed. Use stiff brooms. in an emergency. Sprinkle the burlap with water before placement. Cover a subgrade consisting of gravel. remove it. erecting forms. is clean and moist. The rock surfaces should be roughened and thoroughly cleaned. Lap tar paper edges not less than 1 inch and staple them together.FM 5-428 Chptr 5 Construction Procedures PRELIMINARY PREPARATION 5-42. q Depositing fresh concrete on hardened concrete. q Preparing forms. Cutting rocks out will make the surfaces either vertical or horizontal. or wet sandblasting. or other loose material with tar paper or burlap before placing concrete. and setting reinforcing steel. Join burlap edges by sewing them together with wire. but be sure it is moist before placement to prevent water absorption from the concrete. work the mortar into the rock surfaces using stiff brushes. Finally. To obtain a good bond and a watertight joint when depositing new concrete on hardened concrete. Preparation prior to concrete placement includes compacting. Wet sand-blasting and washing is the best way to prepare old surfaces if the sand deposit can easily be removed Always moisten hardened concrete before placing new concrete. Saturating such forms with water helps to close the joints. high-pressure air. q Moistening clay subgrades. 5-22 . Moisten a subgrade composed of clay or other fine-grained soils to a depth of 6 inches to help cure the concrete. Make the mortar with only FA using the same W/C ratio as the concrete. If the surface of the hardened concrete is covered by a soft layer of mortar or Laitance (a weak material consisting mainly of lime). and that some aggregate particles are partially exposed. make sure that the hardened concrete is nearly level. Remember. Just before placement. water jets. q Planning placement. q Preparing gravel and sand subgrades. Sprinkling the soil with water intermittently will saturate it without making it muddy. moistening subgrade or placing vapor barrier. rather than sloping. Moistening the subgrade is especially important in hot weather to prevent water extraction from the concrete. Never leave pools of water on the old surface when depositing fresh concrete on it. The joint between fresh and hardened concrete is never as strong as a continuous slab. Clean the surface of debris and dry loose material before placing the concrete. check the forms for both tightness and cleanliness. Make sure that the forms are coated with a suitable form oil or coating material so that the concrete will not stick to them. Ideally. If subsequent placements are needed between placements.
avoid horizontal movements that result in segregation. To avoid cracking during settlement. beams. Overfill the form to about 2 inches and remove the excess just before the concrete sets to make sure of a rough. beams. and the amount of reinforcement. q Compaction.FM 5-428 Chptr 5 Construction Procedures PLACING CONCRETE 5-43. and placing the slabs. with a slump of about 6 inches to prevent stone pockets this will help produce a watertight joint. or girders they support. the width of the space between forms. q Placement rate. or girders. Thoroughly consolidate the concrete. For reinforced concrete members. View 1 of Figure 5-13 5-23 . use vertical pipes. stop off the inside form at the construction level. Because paste tends to flow ahead of aggre-gate. unless the free fall into the form is less than 5 feet. between placing columns and walls. For walls. or baffles. Take appropriate steps to control the temperature of fresh concrete and protect the concrete from temperature extremes after placement. When constructing walls. because segregation and a weak surface can result. Layer thickness depends on the type of construction. The principles of proper concrete placement include-q Segregation. Make the mortar with the same water content as the concrete. However. except for columns. including final consolidation and finishing. When placing fresh concrete against or upon hardened concrete. it is tempting to simply drop the concrete directly from its delivery point regardless of form height. the layers should be from 15 to 20 inches thick. then proceed toward the center to prevent water from collecting at the form ends and corners. and against the sides of the forms. Avoid segregation during all operations from the mixer to the point of placement. deposit a 1/2-to 1-inch thick layer of sand cement mortar. suitable drop chutes. Do not allow the first layer to take its initial set before adding the next layer. but preferably 24 hours. q Bonding. Try to place concrete in even horizontal layers. particularly in wall forms containing considerable reinforcement. Place concrete as near to it's final position as possible. Work the concrete thoroughly around reinforcement and embedded fixtures. the layers should be from 6 to 20 inches thick. clean surface. q Consolidation. To save time and effort. When depositing from buckets in mass concrete. Use a mechanical vibrator or a hand spading tool for consolidation. q Maximum drop. allow an interval of at least 4 hours. q Temperature control. To avoid too much pressure on forms for large projects. Take care not to overvibrate. working solidly around all embedded reinforcement and filling all form angles and corners. do not puddle or vibrate it into the form. q Layer thickness. make sure that a good bond develops. Place each layer in one operation and consolidate it before placing the next one to prevent honeycombing or voids. Figure 5-6 suggests several ways to control concrete fall and prevent honeycombing and other undesirable results. Coordinate the placing and compacting so that the concrete is not deposited faster than it can be compacted properly. place the first batches of each layer at the ends of the section. the filling rate should not exceed 5 vertical feet per hour. Before placing the next lift of concrete. WALL CONSTRUCTION 5-44. into the corners.
Space the port openings at about 10-foot intervals up the wall. Concrete placing technique SLAB CONSTRUCTION 5-24 . Figure 5-13. (View 2 of Figure 5-13. Note the different kinds of drop chutes that can place concrete through port openings into the lower portion of the wall.) When placing walls. be sure to remove the spreaders as you fill the forms. Show how to place concrete in the upper portion of the wall.FM 5-428 Chptr 5 Construction Procedures shows the proper way to place concrete in the lower portion of high wall forms.
Mechanical vibrators are best for consolidating concrete. The concrete will be consolidated enough when a thin line of mortar appears along the form near the vibrator. Always deposit the concrete at the bottom of the slope first. An external vibrator is applied to the form and is powered by either an electric motor. Whenever possible. gasoline engine. Withdraw the vibrator vertically at 5-25 . Vibration does not normally damage the lower layers. Any compacting device must reach the bottom of the form and be small enough to pass between reinforcing bars. Be careful not to displace the reinforcing steel because the strength of the concrete member depends on proper reinforcement location. Except for concrete placed underwater. as long as the concrete disturbed in these lower layers becomes plastic under the vibratory action. level the piles and work them together. PRINCIPLES 5-48. The vibrators available in engineer construction battalions are called internal vibrators. but penetrate several inches into the layer underneath to make sure a good bond exists between the layers. such as those having only a 1. Overlap the vibrated areas at each insertion. Consolidation brings enough fine material both to the surface and against the forms to produce the desired finish. such hand tools such as spades. When using an internal vibrator. because the vibrating element is inserted into the concrete. and then place subsequent batches against previously placed concrete. VIBRATION 5-49. Mechanical vibrators consolidate concrete by pushing the CA downward away from the point of vibration. puddling sticks. The process involves carefully working around all reinforcing steel with the compacting device to ensure proper embedding of reinforcing steel in the concrete. or tampers. insert it at about 18-inch intervals into air-entrained concrete for 5 to 10 seconds and into nonair-entrained concrete for 10 to 15 seconds. These practices would result in segregation. may also be used. Stiff mixtures are more economical because they require less cement and present fewer segregation or excessive bleeding problems.FM 5-428 Chptr 5 Construction Procedures 5-45. as shown in view 3 of Figure 5-13.or 2-inch slump. do not use a mix so stiff that it requires too much labor to place it. then proceed up the slope placing each new batch against the previous one. Concrete consolidation eliminates rock pockets and air bubbles. The vibrator should not only pass through the layer just placed. However. place the concrete at the far end of the slab first. CONSOLIDATING CONCRETE 5-47.View 4 of Figure 5-13 shows how to place concrete on slopes. When consolidated. compact or consolidate all concrete after placement. The exact time period that you should leave a vibrator in the concrete depends on its slump. the weight of the new concrete increases the compacting of the previously placed concrete. Do not place the concrete in separate piles. (See Figure 5-14 below. or compressed air. or the paste just appears near the vibrator head.) Vibrators allow placement of mixtures that are too stiff to place any other way. the CA disappears into the concrete. PLACING CONCRETE ON SLOPES 5-46. When constructing slabs. or deposit the concrete in big piles and then move it horizontally to its final position. lower the vibrator into the concrete vertically and allow it to descend by gravity.
Do not vibrate mixes that you can consolidate easily by spading. puddling sticks. Some hand spading or puddling should accompany all vibration. To consolidate concrete by spading insert the spade downward along the inside surface of the forms. because segregation may occur. as shown in Figure 5-15 below. 5-26 . Vibrated concrete has a slump of 5 or 6 inches. Use vibrators to move concrete any distance in the form. Continue spading or puddling until the CA disappears into the concrete. Figure 5-14.FM 5-428 Chptr 5 Construction Procedures about the same gravity rate that it descended. Using a Vibrator to consolidate concrete HAND METHODS 5-50. through the layer just placed into the layer underneath several inches. or various types of tampers. Manual consolidation methods require spades.
Whenever placing concrete underwater. but never above 80°F.FM 5-428 Chptr 5 Construction Procedures Figure 5-15. TREMIE METHOD 5-53. The most common is with a tremie device shown in Figure 5-16 below. If the velocity of flowing water is greater than 10 feet per minute. If concrete is placed in water temperature below 45°F. SUITABLE CONDITIONS 5-52. make sure the concrete temperature is above 60°F when deposited. Consolidation by spading and a spading tool PLACING CONCRETE UNDERWATER 5-51. For best results. make sure that the cofferdams or forms are tight enough to reduce the velocity through the space to be concreted to less than 10 feet per minute. do not place concrete in water whose temperature is below 45°F. You can place concrete underwater using several methods. nor in flowing water whose velocity is greater than 10 feet per minute. Attempting to remove water during this time may cause water to mix inadvertently with concrete thus reducing strength. make sure that the work is done under experienced supervision and that certain precautions are taken. Do not pump water either while placing concrete or for 24 hours thereafter. even though sacked concrete can be placed in water having greater velocities. funnel-shaped pipe into which you 5-27 . A tremie is a long.
Concrete placed with a tremie should have a slump of about 6 inches and a cement content of seven sacks per cubic yard of concrete. The concrete that is placed this way can be slightly stiffer than that placed by tremie. Use several tremies to deposit concrete over a large area. fill the tremie.to 25-foot centers. you can exclude both air and water from the pipe. and the maximum CA size should range from 1 1/2 to 2 inches. The discharge end of the pipe is usually equipped with a gate that you can close to fill the tremie before inserting it into the water. By keeping the tremie constantly filled with concrete. Make soundings frequently to keep the top surface level. When you must move it. taking care not to lose the seal at the discharge end. keeping the top surface of the new concrete as level as possible. lift it carefully out of the newly placed concrete and move it slowly to the new position. lift the tremie a little bit--slowly--to permit the concrete to begin to flow out. spaced on 20. close the gate. When filled and lowered into position. Be sure to supply concrete to all tremies at a uniform rate with no interruptions. About 50 percent of the total aggregate should be sand. You can open the gate from above the water level at the proper time. Pumping concrete directly from the mixer is the best way to do this. and lower it into position again. To start placement. First. fill the bucket completely and cover the top with a canvas flap attached to one side of the bucket only. Suspend large tremies from a crane boom and easily raise and lower them with the boom. Do not move the tremie horizontally through deposited concrete. Do not discharge the concrete before reaching the placement surface. Placing concrete underwater with a tremie CONCRETE BUCKET METHOD 5-54. the discharge end remains continually buried in newly placed concrete. but should still contain seven sacks of cement per cubic yard. SACK METHOD 5-28 . Then lower the bucket slowly into the water without displacing the canvas.FM 5-428 Chptr 5 Construction Procedures feed the concrete. Figure 5-16. you must raise the tremie. Concrete can be placed at a considerable depth below the water surface using open-top buckets having a drop bottom. If the seal is lost. The pipe must be long enough to reach from a working platform above the water level to the lowest point underwater at which you must place concrete.
) This forces the excess concrete built up against the screed face into the low spots. move it back and forth across the concrete using a sawing motion as shown in Figure 5-17. With each sawing motion. The finishing process provides the desired final concrete surface. place concrete underwater using partially filled sacks arranged in header and stretcher courses that interlock the entire mass together. Sometimes there is only a need to correct surface defects. move the screed forward a short distance along the forms. Two of the workers operate the screed while the third pulls excess concrete from the front of the screed. Hand-screed surfaces up to 30 feet wide. In an emergency. or a broomed. 5-29 . the better the concrete product SECTION VIII. Screed the surface a second time to remove the surge of excess concrete caused by the first screeding. or clean the surface. floated. Do not attempt compaction because the less concrete underwater is disturbed after placement. Using a tool called a screed. Screeding brings the surface to the correct elevation by striking off the excess concrete. but expect diminished efficiency on surfaces more than 10 feet wide. fill jute sacks of about 1-cubic foot capacity about two-thirds full. Then lower them into the water. which will stop the tearing action in most cases. placing the header courses so that the sack lengths are at right angles to the stretcher course sacks. This surge is when the concrete seems to grow out of the form into a convex shape. or pavement is rarely placed at the exact specified elevation. SCREEDING 5-57. Cement from one sack seeps into adjacent sacks and thus bonds them together. or troweled finish may be specified. First. sidewalk. (The screed rides on either wood or metal strips established as guides. The top surface of a floor slab. fill bolt holes. If the screed tends to tear the surface--as it may on air-entrained concrete due to its sticky nature--either reduce the rate of forward movement or cover the lower edge of the screed with metal.FM 5-428 Chptr 5 Construction Procedures 5-55. which is a template having a straight lower edge to produce a flat surface or a curved lower edge to produce a curved surface. There are many ways to finish concrete surfaces depending on the effect required. Three workers (excluding a vibrator operator) can screed about 200 square feet of concrete per hour. FINISHING FINISHING OPERATIONS 5-56. Unformed surfaces may require only screeding to proper contour and elevation.
and to compact the concrete at the surface in preparation for other finishing operations.FM 5-428 Chptr 5 Construction Procedures Figure 5-17. Floating has three purposes: to embed aggregate particles just beneath the surface. Screeding operation FLOATING 5-58. work the surface sparingly using either a wood or aluminum-magnesium float. If a surface smoother than that obtained by screeding is required. high spots. to remove slight imperfections. 5-30 . or a finishing machine. and low spots. The wood float is shown in use in view 2 of Figure 5-18. Begin floating immediately after screeding while the concrete is still plastic and workable.
follow floating with steel troweling (see Figure 5-19). smooth.FM 5-428 Chptr 5 Construction Procedures Figure 5-18. to give the finished concrete a much smoother surface. This fine material will form a thin weak layer that will scale or wear off under use. Troweling should leave the surface. Wood floats and floating operations Do not overwork the concrete while it is still plastic or an excess of water and paste will rise to the surface. and free from marks and ripples. Too much troweling too soon tends to produce crazing and reduces durability. TROWELING 5-59. even. To produce a coarse texture as the final finish. 5-31 . For a dense. Do not use either cement or water as an aid in finishing the surface. float the surface a second time after it partially hardens. Use a long-handled wood float for slab construction as shown in view 3 of Figure 5-18. smoother finish. To avoid cracking and dusting of the finished concrete. However. Use an aluminum float the same way as the wood float. begin aluminum floating when the water sheen disappears from the freshly placed concrete surface. Begin this procedure when the moisture film or water sheen disappears from the floated surface and the concrete has hardened enough to prevent fine material and water from working to the surface. Delay this operation as long as possible. too long a delay in troweling makes the surface hard to finish properly.
Steel finishing tools and troweling operation Avoid all wet spots if possible. When a wear resistant and durable surface is required.FM 5-428 Chptr 5 Construction Procedures Figure 5-19. keeping the trowel flat against the surface. it is poor practice to spread dry cement on the wet surface to absorb excess water. do not resume finishing operations until the water has been absorbed. After waiting 10-15 minutes. When severe scoring is not desirable. and passing the trowel over the surface produces a ringing sound. However. tilt the trowel slightly and exert heavy pressure to compact the surface thoroughly. by a second light troweling over the surface with a circular motion immediately following the first regular troweling. or mopped up. The grooves cut by the broom should not be more than 3/16 inch deep. broom the concrete before it hardens thoroughly with a straw broom of fibers at least 4 1/2 inches long. but not slippery. evaporated. Obtain a surface that is fine-textured. Hair cracks usually result from a concentration of water and fines at the surface due to overworking the concrete during finishing operations. when rough scoring is specified. Close cracks that develop before troweling by pounding the concrete with a hand float. When a hard steel-troweled finish is specified. 5-32 . Produce a nonskid surface by following the floating operation. produce the broomed finish using a hairbrush after troweling the surface once to a smooth finish. The direction of scoring when brooming should be at right angles to the direction of any traffic. BROOMING 5-60. Rapid drying or cooling aggravates such cracking. When they do occur. such as in some floors and sidewalks. During this final troweling. follow the first regular troweling with a second troweling only after the concrete is hard enough that no paste adheres to the trowel. use a stiff broom made from either steel wire or coarse fiber.
FINISHING PAVEMENT 5-62. then screed again. called belting. To properly cure any mortar used as an aid in this process and left on the surface. FINISHING REPAIRS 5-65. 6 by 10 inches wide and 12 by 18 feet long. only two passes of the machine finisher are needed to produce a satisfactory surface. obtain the final surface finish by dragging a clean piece of burlap along the pavement strip longitudinally. If forms are in good alignment and firmly supported. vibrate. fitted with a handle at each end. A machine finish is needed when the concrete takes its initial set. The surface should have no coating of weak mortar or scum that will later scale off. The float oscillates longitudinally as it moves transversely (crosswise). knock off all small projections. 5-33 . Hand floating often does more harm than good. sometimes there may be a need to use a longitudinal float to decrease variations running lengthwise in the surface. Scaling is a good example. When the water sheen disappears. especially at construction and expansion joints. Technical Manual (TM) 5-331D describes the operation and maintenance of machine finishers. because it is likely to scale off and mar the surface appearance. A 10-foot straightedge pulled from the center of the pavement to the form removes any minor surface irregularities as well as laitance. The sequence of the operation is: screed. Generally. overworking can cause the wearing surface to deteriorate. Unless the workers use considerable care as the straightedge approaches the form. a sufficiently thick layer of concrete should build up ahead of the screed to fill all low spots completely. Section XII in this chapter covers concrete repair in detail. and prepare them for filling. and repair any honeycombed areas. it will ride up on the concrete causing a hump in the surface. Restrict the mortar layer to a minimum. This operation. How-ever. rub the surface first with coarse carborundum stones so that the aggregate does not pull out. keep it damp for 1 to 2 days after it sets. Allow the concrete to cure before the final rubbing with finer carborundum stones. Adjust the second screed to carry enough concrete ahead of it so that the screed continually contacts the pavement. fill tie-rod holes. MACHINE FINISHING 5-63.FM 5-428 Chptr 5 Construction Procedures RUBBING 5-61. Such a float is made from wood. Set both the screeds and vibrators on the machine finisher to produce the specified surface elevation as well as a dense concrete. The most uniform and at-tractive surface requires a rubbed finish. and if the concrete has the correct workability. As soon as possible after removing the forms. but still remains in workable condition. A surface finish having a satisfactory appearance can be produced simply by using plywood or lined forms. Be sure to round all pavement corners with an edging tool. It is operated on form-riding bridges by two workers. Keep the concrete damp while rubbing. clean out expansion joints. requires two workers. one on each side of the form. HAND FLOATING 5-64. As soon as the concrete hardens.
and clothing. Mortar left on the surface overnight is very difficult to remove. The moisture is needed for any chemical reactions. CLEANING WITH MORTAR 5-67. clean concrete surfaces in the shade on a cool. Remove the excess mortar by rubbing the surface with a second piece of clean burlap. Delay this step long enough to prevent smearing. HYDRATION 5-34 . Allow the mortar to set several hours and cure for 2 days. CURING IMPORTANCE OF CURING TO HYDRATION 5-70. Precede acid washing by a 2-week period of moist curing. Remove the acid immediately and thoroughly by flushing with clean water. particularly rust. wet the surface and while it is still damp scrub it thoroughly using a stiff bristle brush with a 5 to 10 percent solution of muriatic acid. If possible. For best results. Concrete surfaces are not always uniform in color when forms are removed. but complete it before the mortar hardens. Methods of cleaning with mortar includes-q Using a solution. Curing keeps concrete moist. After curing. SANDBLASTING 5-68. clean the surface using one of the methods described below. allowing the mortar to harden enough so that the trowel will not remove it from the small holes. follow the acid washing with four more days of moist curing. Complete one section without stopping. An alternate method is to simply rub the mortar over the surface using clean burlap. CLEANING WITH ACID 5-69. Use this method when surface staining is not severe. Remove excess mortar with a trowel after 1 or 2 hours. The mortar should have the consistency of thick cream and the surface should be almost dry.FM 5-428 Chptr 5 Construction Procedures CLEANING THE SURFACE 5-66. be sure to wear goggles to protect your eyes and take precautions to prevent acid from contacting hands. When handling muriatic acid. This removes all excess mortar remaining after the second burlap rubbing and produces a surface having a uniform appearance. by lightly sandblasting the surface. rub it with dry burlap to remove any loose material. q Rubbing with burlap. This method is more effective than washing with acid. Then immediately scour the surface vigorously using a wood or cork float. Apply the mortar with a brush after repairing all defects. If appearance is important. SECTION IX. After the surface dries. There should be no visible mortar film remaining after the rubbing. permit the surface to dry and then sand it vigorously with number 2 sandpaper. First. Clean the surface with a cement-sand mortar consisting of 1 part portland cement and 1 1/2 to 2 parts fine sand. arms. Use white portland cement for a light-colored surface. Completely remove surface stains. damp day.
This reaction. The length of time that concrete is protected against moisture loss depends on the type of cement used. and the resulting strength of the final concrete. strength. Both the rate and degree of hydration. During this period. and future exposure conditions. called hydration. There are numerous facts which affect the curing process. depend on the curing process that follows placing and consolidating the plastic concrete. watertightness. mix proportions. q Length of curing period. Curing is the period of time from consolidation to the point where the concrete reaches its design strength. the weather. Figure 5-20 shows how moist curing affects concrete's compressive strength. For most structural use. size. mix proportions. the curing period for cast-in-place concrete is usually 3 days to 2 weeks. and shape of the concrete mass. 5-35 . The properties of concrete. hydration ceases and cannot be restarted. cure or improve with age as long as moisture and temperature conditions are maintained and are favorable to continued hydration. Hydration continues indefinitely at a decreasing rate as long as the mixture contains water and the temperature conditions are favorable. cement type. the required strength. depending upon such conditions as temperature. Adding water to portland cement to form the water-cement paste that holds concrete together starts a chemical reaction that makes the paste into a bonding agent. The period can vary from a few days to a month or longer. such as freeze and thaw resistance. and volume stability. CURING FACTORS 5-72. and so forth. Bridge decks and other slabs exposed to weather and chemical attack usually require more extended curing periods.FM 5-428 Chptr 5 Construction Procedures 5-71. take steps to keep the concrete moist and as near to 73°F as practicable. q Importance of moisture and temperature. wear resistance. produces a stone-like substance--the hardened cement paste. Once the water is removed.
Can dry out. Curing methods Method Sprinkle with water or cover with wet burlap Strawing Moist earth Advantage Excellent results if constantly kept wet. blow away.FM 5-428 Chptr 5 Construction Procedures Figure 5-20. in some cases. undersirable temperature. Insulator in water. Disadvantage Likelihood of drying between sprinklings. at a favorable hydration tem-perature. or burn. Pounding on flat surfaces Excellent result. Table 5-5 lists several of these effective curing methods and their advantages and disadvantages. Moist curing effect on compressive strength of Concrete CURING METHODS 5-73. They fall into two categories: those that supply additional moisture and those that prevent moisture loss. Stains concrete. in freezing weather 5-36 . but messy. Table 5-5. Removal problem. Cheap. Difficult on vertical walls Can dry out. maintains uniform Requires considerable labor. Several curing methods will keep concrete moist and.
q Covering with wet material. The disadvantages of this method are the expense involved and volume of water required. Plastic film METHODS THAT SUPPLY ADDITIONAL MOISTURE 5-74. Both sprinkling and wet covers add moisture to the concrete surface during the early hardening or curing period. which is especially important in hot weather. Inadequate coverage allows drying out.FM 5-428 Chptr 5 Construction Procedures Curing compounds Inexpensive. Light and easy to handle. earth. horizontal placements can be flooded by creating an earth dam around the edges. Unless pigmented. requires reasonable care and tear. q Flooding with water. Pigmented for heat protection. do not allow the concrete to dry out between applications. Leave them in place and keep them moist during the entire curing period. and submerging the entire concrete structure in water. These are used extensively in curing concrete. must be weighted down to prevent blowing away. must be patched. concrete can get too hot. excellent protection. This type of covering includes wet burlap. This is an excellent way to cure concrete. Waterproof paper Excellent protection. storage and handling problem. cotton mats. prevents drying. Heavy cost can be excessive. if sprinkling only at intervals. 5-37 . Sprayer needed. Figure 5-21 shows a typical application of wet burlap. Lay the wet coverings as soon as the concrete hardens enough to prevent surface damage. Must be kept in rolls. and other moisture-retaining fabrics. straw. Methods that gives additional moisture are-q Sprinkling continually with water. easy to apply. Watertight. They also provide some cooling through evaporation. However. Film can be broken or tracked off before curing is completed. If practical.
Use brushes to apply curing compound to formed surfaces. Respray any concrete surfaces subjected to heavy rain within 3 hours of application. Wet the surface with a fine water spray before covering. These compounds permit curing to continue for long periods while the concrete is in use. especially if the surface was steel-troweled to a hard finish. and breaking the surface film continuity. Moisture loss can be prevented by sealing the surface with-q Waterproof paper. Lap adjacent sheets 12 inches or more and weigh their edges down to form a continuous cover having completely closed joints. Apply them with spray equipment. These are suitable not only for curing fresh concrete. Use waterproof paper (see Figure 5-22) to efficiently cure horizontal surfaces and structural concrete having relatively simple shapes. to odd slab widths or shapes of fresh concrete.FM 5-428 Chptr 5 Construction Procedures Figure 5-21. some thin plastic sheets may discolor hardened concrete. or liquid-membrane-forming compounds. However. Moisture lost prevention methods include laying waterproof paper. overlap. but to further cure concrete following form removal or initial moist curing. weighing down of edges. 5-38 . q Plastic. opening the surface to too much compound penetration. Do not use curing compounds if a bond is necessary because curing compounds can prevent a bond from forming between hardened and fresh concrete. and surface wetting requirements of plastic film are similar to those of waterproof paper. Certain plastic film materials are used to cure concrete. q Curing compounds. such as hand-operated pressure sprayers. The coverage. See TM 5-337 for application details. The paper should be large enough to cover both the surfaces and the edges of the concrete. They provide lightweight. effective moisture barriers that are easy to apply to either simple or complex shapes. plastic film. but do not use brushes on unformed concrete due to the risk of marring the surface. Leave the coverings in place during the entire curing period. Curing a wall with wet burlap sacks METHODS THAT PREVENT MOISTURE LOSS 5-75. and to exposed concrete surfaces following form removal. and simply leaving forms in place.
Keep wood forms moist by sprinkling. especially when placing large exposed slabs. Concreting in hot weather poses some special problems such as strength reduction and cracking of flat surfaces due to too-rapid drying. The combination of hot dry weather and high winds is the most severe condition. This leads to difficulty in finishing flat surfaces. During hot weather take steps to limit concrete temperature to less than 90°F. Forms provide enough protection against moisture loss if the exposed concrete surfaces are kept wet. but problems can arise even with concrete temperatures less than 90°F. limitations are imposed on placing concrete during hot weather and on the maximum temperature of the concrete. q Water requirements.FM 5-428 Chptr 5 Construction Procedures q Forms. Figure 5-22. PROBLEMS ENCOUNTERED 5-77. dry weather. Concrete that stiffens before consolidation is caused by too-rapid setting of the cement and too much absorption and evaporation of mixing water. EFFECTS OF HIGH CONCRETE TEMPERATURES 5-78. placed. Therefore. Waterproof paper used for curing SECTION X. Figure 5-23 shows a linear relationship between an increase in concrete temperature and the increase in mixing water 5-39 . quality and durability suffer when concrete is mixed. a particular concrete consistency generally requires more mixing water than normal. Because high temperatures accelerate hardening. and cured at high temperatures. TEMPERATURE EFFECTS HOT-WEATHER CONCRETING 5-76. especially during hot. Three common things affect high concrete temperatures.
However. and because of the greater difference between the high temperature at the time of hardening and the low temperature to which the concrete later drops. in-creasing water content without increasing cement content results in a higher W/C ratio. If water content is increased to maintain the same slump (without changing the cement content). Concrete mix water requirements as temperature increases 5-40 . In hot weather the tendency for cracks to form increases both before and after hardening. the reverse happens at later ages. Cracks can also develop in the hardened concrete because of increased shrinkage due to a higher water requirement. the reduction in com-pressive strength is even greater than that shown in Figure 5-24. which has a harmful effect on the strength and other desirable properties of hardened concrete. Rapid water evaporation from hot concrete can cause plastic shrinkage cracks even before the surface hardens. Cracks. Compressive strength of concrete. Tests using identical concretes having the same W/C ratio show that while higher concrete temperatures increase early strength.FM 5-428 Chptr 5 Construction Procedures q required to maintain the same slump. q Figure 5-23. Figure 5-24 demonstrates the effect of high concrete temperatures on compressive strength.
q Insulating water supply lines and tanks or painting them white. q Insulating mixer drums or cooling them with sprays or wet burlap coverings. in lowering concrete temperature. add slush ice to chill the water. reinforcing steel.FM 5-428 Chptr 5 Construction Procedures Figure 5-24. In extreme cases. 5-41 . q Cooling CA by sprinkling. Figure 5-25 shows the effects of the mixing water and aggregate temperatures on the temperature of fresh concrete. However. Mixing water is the easiest to cool and is also the most effective. thereby avoiding too much mixing water. the concrete temperature depends primarily on the aggregate temperature. q Working only at night. q Sprinkling forms. pound for pound. because aggregate represents 60 to 80 percent of the concrete's total weight. q Shading those materials and facilities not otherwise protected from the heat. The most practical way to obtain a low concrete temperature is to cool the aggregate and water as much as possible before mixing. Lower the temperature of fresh concrete by-q Using cold mixing water. and subgrade with cool water just before placing concrete. Effect of high temperature on concrete compressive strength at various ages COOLING CONCRETE MATERIALS 5-79.
and 3 of Table 5-6. thereby shortening the length of time available to handle and finish the concrete. or use other similar means of retaining moisture for longer periods. FREEZE PROTECTION 5-82. include provisions for heating the plastic concrete and maintaining favorable temperatures after placement. Take extra care to avoid cold joints when placing it. Note that lower temperatures are given for heavier 5-42 .FM 5-428 Chptr 5 Construction Procedures Figure 5-25. Loosen the forms as soon as possible without damaging the concrete and cover the concrete with water. The temperature of fresh concrete should not be less than that shown in lines 1. 2. Then frequent sprinkling. because water evaporates rapidly from the concrete and the efficiency of curing compounds is reduced. Do not suspend concreting during the winter months. COLD WEATHER CONCRETING 5-81. Concrete transport and placement must be completed as quickly as possible. Leaving forms in place is not a satisfactory way to prevent moisture loss when curing concrete in hot weather. Proper curing is especially important in hot weather due to the greater danger of crazing and cracking. High temperatures increase the hardening rate. Take the necessary steps to protect the concrete from freezing in temperatures of 40°F or lower during placing and during the early curing period. But curing is also difficult in hot weather. Mixing water temperatures required to produce concrete of required temperature SPECIAL PRECAUTIONS 5-80. In your prior planning. use of wet burlap.
5-43 . the concrete's temperature should not be less than that shown in line 4 of Table 5-6 at the time of placement. further thermal protection will need to be provided to make sure that subsequent concrete temperatures do not fall below the minimums shown in line 5 of Table 5-6 for the time periods given in Table 5-7. *Made with Type I. **Made with Type III or high-early-strength cement or an accelerator or an extra 100 lbs of cement. or normal cement. To ensure durability and strength development. Size. Table 5-7. Because additional heat is lost during transporting and placing. High concrete temperatures require more mixing water for the same slump and this contributes to cracking due to shrinkage. above 30oF 0oto 30oF below 0oF 60 65 70 55 50 12-36 inches 55 60 65 50 40 36-72 inches 50 55 60 45 30 Adapted from recommended practice for cold weather concerning (ACI 306R-78). Table 5-6. Recommended concrete temperatures for cold-weather construction Line Placing and Curing Conditions Section. Table 5-6. fresh concrete as mixed for weather indicated. II. since the heat loss is greater. in Inches < 12 inches 1 2 3 4 5 Minimum temperature. Concrete temperatures over 70°F are seldom necessary because they do not give proportionately longer protection from freezing. fresh concrete as placed. the temperatures given for the freshly mixed concrete are higher for colder weather. since less heat dissipates during the hydration period. Minimum temperature. Maximum allowable gradual drop in temperature throughout first 24 hours after end of protection. oF.FM 5-428 Chptr 5 Construction Procedures mass sections than thinner sections. oF. oF. Minimum Thickness. To prevent freezing. Recommended duration of protection for concrete placed in cold weather (air-entrained concrete) Degree of Normal Exposure to Concrete* Freeze-Thaw No exposure 2 days High-EarlyStrength Concrete** 1 day 2 days Any exposure 3 days NOTE: Protection time for durability is at the temperature indicated in line 4.
Figure 5-26. low temperatures retard hardening and compressive strength gain. Figure 5-26. and cured at temperatures below 73°F is lower than concrete cured at 73°F during the first 28 days. demonstrates which temperature affects the hydration rate of cement.FM 5-428 Chptr 5 Construction Procedures EFFECTS ON LOW CONCRETE TEMPERATURES 5-83. Effects of low temperature on concrete compressive strength at various ages 5-44 . but becomes higher with age and eventually overtakes the strength of the concrete cured at 73°F. Figure 5-27 shows that the early strengths achieved by Type III or high-early-strength cement are higher than those achieved by Type I cement. placed. The graph shows that the strength of concrete mixed. Concrete placed at temperatures below 73°F must be cured longer. Remember that strength gain practically stops when the moisture required for hydration is removed.
Aggregate in temperatures above freezing seldom has to be heated. If aggregate is thawed in the mixer. the FA used to produce concrete may need to be heated. q Heating water. water's stored heat can be used to heat other concrete ingredients. For example. q Heating aggregate. As shown in Figure 5-28. but the resulting variable moisture content can cause problems in controlling the amount of mixing water. Use any of several methods to heat aggregate. This graph is reasonably accurate for most ordinary concrete mixtures. Mixing water is easier to heat because it can store five times as much heat as solid materials having the same weight. The average temperature of the aggregate should not exceed 150°F. Although aggregate and cement weigh much more than water. Another method is to inject live steam directly into a pile of aggregate. Relationship between early compressive strengths of portland cement types and low curing temperatures COLD WEATHER TECHNIQUES 5-84. but at temperatures below freezing. if the weighted 5-45 . mixing water should not be hotter than 180°F so that. check for too much water content. in some cases.FM 5-428 Chptr 5 Construction Procedures Figure 5-27. Cover the stockpiles with tarpaulins to both retain and distribute the heat. both aggregate and water must be heated. Figure 5-28. When heating concrete ingredients. the thaw-frozen aggregate makes proper batching easier and avoids pockets of aggregate in the concrete after placement. combine them in the mixer first before adding the cement. When either aggregate or water is heated above 100°F. shows how the temperature of its ingredients affects the temperature of fresh concrete. One method for small jobs is to pile it over metal pipes containing fires or stockpile aggregate over circulating steam pipes.
Preparing for placement. Using high-early-strength cement. Using accelerators. use an extra sack of cement per cubic yard rather than calcium chloride. if the grade permits. do not try to lower the freezing point of concrete with accelerators (antifreeze compounds or similar products). Be sure to thaw the ground enough to ensure that it will not refreeze during the curing period. heat the water to its maximum temperature of 180°F and heat the aggregate to make up the difference. and earlier use of the structure. But be careful in using accelerators containing chlorides where an in-service potential of corrosion exists. If only a few inches of the subgrade are frozen. as long as you limit it to no more than 2 percent of calcium chloride by weight of cement.FM 5-428 Chptr 5 Construction Procedures q q q average temperature of aggregate is below 36°F. by steaming or. Never place concrete on a frozen subgrade because severe cracks due to settlement usually occurs when the subgrade thaws. However. Also. 5-46 . by spreading a layer of hot sand or other granular material. When sulfate-resisting concrete is required. High-early-strength cement produces much higher hydration temperatures which can offset some of the cold water effects. and the desired fresh concrete temperature is 70°F. cost savings in heating and protection. because the large quantities required seriously affect compressive strength and other concrete properties. earlier flatwork finishing. Other benefits include early reuse of forms and shore removal. you may use smaller amounts of additional cement or such accelerators as calcium chloride to speed up concrete hardening in cold weather. such as in prestressed concrete or where aluminum inserts are planned. thaw the surface by burning straw. Do not substitute accelerators for proper curing and frost protection.
favorable curing conditions can restore it to nearly normal.FM 5-428 Chptr 5 Construction Procedures Figure 5-28. when using heated enclosures during the winter. Leave them in place as long as practicable. although it 5-47 . However. Forms distribute heat evenly and help prevent drying and overheating. Concrete placed in forms or covered by insulation seldom loses enough moisture at 40oF to 55oF to impair curing. Effect of temperature of materials on temperature of fresh concrete CURING 5-85. moisten curing concrete to offset the drying effects. Keep the concrete at a favorable temperature until it is strong enough to withstand both low temperatures and anticipated service loads. If concrete freezes only once at an early age. Concrete that freezes shortly after placement is permanently damaged.
The easiest way to control the temperature inside the enclosure is with live steam. If there is any tendency for the forms to bind around the ornament. SECTION XI. q Live steam. Unless enclosures are properly vented. In cold weather. If it is necessary to wedge between the concrete and the forms. Ties may be removed as early as 24 hours after casting to loosen forms slightly and permit entry of curing water between form and concrete. or other materials to enclose and protect curing concrete at below-freezing temperatures. do not use carbon monoxide-producing heaters (salamanders or other fuel-burning heaters) when curing concrete for 24 to 36 hours after curing. Use a curing compound after removing the protection if the air temperature is above freezing. The manufacturers of these materials can usually provide information on how much insulation is necessary to protect curing concrete at various temperatures. Forms recessed into the concrete require special care in stripping. removal of form work should be deferred or form work should be replaced with insulation blankets to avoid thermal shock and consequent crazing of the concrete surface. Wedging should be done gradually and should be accompanied by light tapping on the piece to crack it loose from the concrete. Because the concrete's corners and edges are the most likely to freeze. Embedded wood forms are generally left in place as long as 5-48 . use only wooden wedges. Provide adequate minimum temperatures during the entire curing period. plastic sheets. BASIC CONSIDERATIONS 5-87. A pinch bar or other metal tool should never be placed against exposed concrete to wedge forms loose. begin stripping some distance away from the ornament and work toward it. Wall forms should not be removed until the concrete has thoroughly hardened. cornice. building board. Make sure enclosures are sturdy and reasonably airtight. Careless workers can cancel out the value of good detailing and planning by indiscriminate use of the wrecking bar. q Heated enclosures. the pressure of the forms against projecting corners will be relieved so that there will be less chance of spalling sharp edges. Use wood. Build a wood framework and cover it with tarpaulins or plastic sheets. or other projecting ornament. because its moisture offsets the rapid drying that occurs when very cold air is heated. (See TM 5-349 for details of cold weather concreting. q Insulation blankets or bats.) Three methods for maintaining proper curing temperatures are described below. FORM REMOVAL FORM STRIPPING 5-86. check them frequently to determine the effectiveness of the protective covering. and allow for free circulation of warm air. Ornamental molds must be left in place until they can be removed without damage to the concrete surface. When fed into an enclosure. 5-88. When stripping forms in the vicinity of a belt course. Air-entrained concrete is less susceptible to freeze damage than nonair-entrained concrete. but specified curing should begin as early as possible in warm weather. Never remove an embedded form with a single jerk. canvas.FM 5-428 Chptr 5 Construction Procedures will neither weather as well nor be as watertight as concrete that has never frozen. live steam is an excellent and practical curing aid during extremely cold weather.
there must be no excessive deflection or distortion and no evidence of cracking or other damage to the concrete. temperature. 2. the type of test. Such approved load should not exceed the live load for which the member was designed unless provision has been made by the engineer architect to allow for temporary construction loads. Table 5-8. Ideally. and the minimum strength standards should be stated clearly in specification. it is possible to damage corners and edges during stripping and for excessive creep deflections to occur.500 psi or two-thirds of the design strength. should also be specified. and walls until these structural units are strong enough to carry their own weight and any approved superimposed load. If strength tests are to be the basis for the designers. a reliable basis for determining the earliest proper stripping time is necessary. and the most reliable basis is furnished by test specimens cured under job conditions.) The curing record including the time. 5-93. Since early form removal is usually desirable so that forms can be reused. STRIPPING TIME BASED ON CONCRETE STRENGTH 5-89. for example. On jobs where the engineer has made no provision for approval of shore and form removal based on strength and other considerations peculiar to the job. 5-92. The embedded items should be separate from or loosely attached to the main form so that they will remain in place when the main form is stripped. due either to removal of support or to the stripping operation. (The specimens must not be confused with those cured under laboratory conditions to evaluate 28-day strength of the concrete. as well as the weather record. and method for both the concrete structure and the test specimens. as well as who should take them and perform the tests. Table 5-8 shows the minimum time forms and supports should remain in place under ordinary conditions. will assist both the engineer and the project officer in determining when forms can be safely stripped. instructions to the project officer on form removal. 5-91. The number of test specimens. For some applications. 5-90. a definite strength must be obtained. Supporting forms and shores must not be removed from beams. In general. even when concrete is strong enough to show no immediate distress or deflection under a load. forms and supports for suspended structures can be removed safely when the ratio of cylinder test compressive strength to design strength is equal to or greater than the ratio of total dead load and construction loads to total design load with a minimum of 50 percent of design compressive strength being required. The strength of the concrete necessary before form work is stripped and the time required to attain it vary widely with different job conditions. test beams and cylinders should be job cured under conditions which are similar to those for the portions of the concrete structure which the test specimens represent. the method of evaluating. When forms are stripped. Recommended form stripping time Forms Walls1 Setting Time 12-24 hours 5-49 .FM 5-428 Chptr 5 Construction Procedures possible so they will shrink away from the concrete. Forms for vertical members such as columns and piers may be removed before those for beams and slabs. floors. However. It should be kept in mind that specimens which are relatively small are more quickly affected by freezing or drying conditions than concrete in the structure.
FM 5-428 Chptr 5 Construction Procedures Columns1 Beams and Girders1 (sides only) Pan joist forms3 q 12-24 hours 12-24 hours 30 inches wide or less Over 30 inches wide 3 days 4 days q Where Design Live Load is <DL >DL Joist. or girder soffits4 q Under 10 feet of clear span between supports 10 to 20 feet of clear span between supports Over 20 feet of clear span between supports 7 days2 4 days q 14 days2 7 days q 21 days2 14 days Floor slab4 q Under 10 feet of clear span between supports 10 to 20 feet of clear span between supports Over 20 feet of clear span between supports 4 days2 3 days q 7 days2 4 days q 10 days2 7 days 5-50 . beam.
Preliminary procedures includes-q Inspection. the best bonds are developed and are more likely to be as durable and permanent as the original work. Although repairs are costly and time-consuming. Do not jerk the forms from the concrete after wedging at one end. when repairs are made immediately after form removal. 4The distances between supports refer to structural supports and not to temporary form work or shores. keep the surrounding concrete wet for 5-51 . Therefore. bolt holes. inspect the concrete for such surface defects as rock pockets. q Timely repair. use half of values shown. repairs later loosen. such forms also support form work for slabs. or soffits. On new work.FM 5-428 Chptr 5 Construction Procedures NOTE: These periods represent the cumulative number of days or fractions thereof not necessarily consecutive. during which the temperature of the air surrounding the concrete is above 50oF. 1Where FORM REMOVAL PROCEDURES 5-94. PRELIMINARY PROCEDURES 5-96. 2Where form may be removed without disturbing shores. or form-stripping damage. ridges at form joints. Withdraw all nails while stripping and immediately clean and oil all forms to be reused. Forms are designed and constructed so that their removal does not harm the concrete. Before placing mortar or concrete into patch holes. beams. SECTION XII. while the concrete is quite green. Following form removal. Remove objectionable ridges and bulges by carefully chipping and rubbing the surface with a grinding stone. field experience dictates that steps in the repair procedure cannot be omitted or performed carelessly without harming the serviceability of the repair work. but not less than 3 days. REMOVING RIDGES AND BULGES 5-97. and allow water to permeate the structure. If they are not properly performed. PATCHING NEW CONCRETE 5-98. the removal times of the latter should govern. crack at the edges. or the edges will break. The form must be stripped carefully to avoid damaging the surface. make all repairs within 24 hours after removing forms. inferior quality. 3These are the type that can be removed without disturbing forming. REPAIRING NEW CONCRETE 5-95. bulges.
Start curing the patch as soon as possible to avoid early drying. Cut the edges either as straight as possible at right angles to the surface. or undercut them slightly to make a key at the edge of the patch. Fill tie-rod holes extending through the concrete with mortar. Do not apply a single shallow layer of mortar on top of honeycombed concrete. Mix the mortar as dry as possible with just enough water to compact tightly when forced into place. Small Patches 5-99. Keep the surfaces of the resulting holes moist for several hours before applying the mortar. because moisture will form in the voids and subsequent weathering will cause the mortar to spall off. tarpaulins. down to solid concrete. or membrane curing compounds. make the patch match the adjacent surface by pressing a piece of the form lining against the fresh patch. Patches are usually darker in color than the surrounding concrete. mix some white cement into the mortar or concrete and use as a patch. such as rock pockets or honeycomb. pack small amounts of mortar into place carefully. When filling bolt holes. Instead. Then brush a grout made from cement and water mixed to a creamy consistency into the hole surfaces before applying the patch material. using a pressure gun similar to an automatic grease gun. Make rough scratches in each layer to improve the bond with the succeeding layer. Flat Surfaces 5-52 . Reinforce such patches and dowel them to the hardened concrete as shown in Figure 5-29. 5-100. chip out small defective areas. Repairing large and deep holes in new concrete Bolt and Tie-Rod Holes 5-101. Patch large or deep holes with concrete held in place by forms. Allow the mortar to set as long as possible to reduce shrinkage and make a more durable patch. If absorptive form lining was used.FM 5-428 Chptr 5 Construction Procedures several hours. and smooth the surface of the last layer to match the adjacent surface. Figure 5-29. Use damp burlap. If appearance is important. Make a trial mix to determine the best proportion of white and gray cements to use. Fill shallow patch holes with mortar placed in layers not more than 1/2 inch thick.
FM 5-428 Chptr 5 Construction Procedures 5-102. In large structures such as walls. First chip an area at least 1 inch deep with edges at right angles to the surface. PRELIMINARY PROCEDURES 5-104. If the old concrete contains reinforcement bars. curbs. preferably overnight. thoroughly clean the cut surfaces using air or water or both. Then screed the patch as shown in view 3 of Figure 5-30. as shown in view 2 of Figure 5-30. and slabs. make sure the old concrete is perfectly sound. After removing weakened material and loose particles. if possible. Keep the area surrounding the repair continuously wet for several hours. The repair depth depends on many conditions. Use 5-53 . Wetting is especially important in repairing old concrete because a good bond will not form without it. before filling the hole. PATCHINH OLD CONCRETE 5-105. Remember that it is far better to remove too much old material than not enough. View 1 of Figure 5-30 shows why feathered edges around a flat patch break down. remove only the loose material. Patching flat surface in new concrete OLD CONCRETE 5-103. allow a clearance of at least 1 inch around each exposed bar. first determine how much material to remove by thoroughly inspecting the defect. When repairing old concrete. If the old and new concrete will join on a surface exposed to weathering or chemical attack. the repair should be at least 6 inches deep. Figure 5-30. The fresh concrete should project slightly beyond the surface of the hardened concrete. piers. Allow it to stiffen before troweling and finishing to match the adjacent surfaces. In this case. Remove all concrete of questionable quality unless nothing would be left.
Reinforce deep patches to the hardened concrete. The design and construction of such forms often require a lot of cleverness. place the new concrete into the hole in layers and thoroughly tamp each layer. The patch concrete should be a low slump mixture allowed to stand for awhile to reduce shrinkage. Following the wetting period. Forms may be needed to hold the patch concrete in place. but well-designed and properly constructed forms are important in concrete repair.FM 5-428 Chptr 5 Construction Procedures rectangular patches on small areas. cutting 1 to 2 inches vertically into the old concrete to eliminate thin or feathered edges. Good curing is essential. 5-54 . Begin curing as soon as possible to avoid early drying.
When concrete and steel are used together. but relatively weak in tension. Beams command the most study. When steel reinforcements in concrete help carry imposed loads. compression members. From the structural engineering viewpoint.FM 5-428 Chptr 6 Reinforced-Concrete Construction Chapter 6 Reinforced-Concrete Construction 6-1. instead of being uniformly distributed. 6-1 . REINFORCED CONCRETE 6-3. or axle steel. one makes up for the deficiency of the other. The concrete's beam strength is increased greatly by embedding steel in the tension area as shown in Figure 6-1. with lugs or projections on their surfaces. It is available in sheets and rolls and is widely used as reinforcement in floors and walls. DEVELOPMENT AND DESIGN PRINCIPLES AND DEFINITIONS 6-2. The bars are made from billet steel. the combination is reinforced concrete. because the bending stress varies over the beam cross section. The most common type of steel reinforcement employed in concrete building construction consists of round bars. Concrete is strong in compression. usually of the deformed type. and bending members called beams. rail steel. conforming to rigid specifications. SECTION I. the three main elements that support live loads in a building are tension members. The reverse is true for slender steel bars. Welded-wire fabric is another type of reinforcement that consists of a series of parallel-longitudinal wires welded at regular intervals to transverse wires. The purpose of the surface deformations is to develop a greater bond between the concrete and the steel.
horizontal steel bars well embedded in the tension area provide tensile resistance. The design theory of reinforced-concrete beam is based on the assumption that a bond develops between the reinforcement and the concrete that prevents relative movement between them as the load is applied. How much bond strength develops depends largely on the area of contact between the two materials. web reinforcement can prevent beams from failing in diagonal tension. Instead. tensile strength is less than one-half the shear strength. Bond Strength is the measure of effective grip between the concrete and the embedded-steel bar. whereas. TENSILE STRENGTH 6-5. The concrete's tensile strength is such a small percentage of the compressive strength that it is ignored in calculations for reinforced-concrete beam. 6-2 . The failure of a concrete slab subjected to a downward concentrated load is due to diagonal tension. Because of their superior bonding value. BOND STRENGTH 6-6. bars having a very rough surface (deformed bars or rebars see Figure 6-2) have replaced plain bars as steel reinforcement. Cross section of a concrete beam showing location of reinforcement in tension SHEAR STRENGTH 6-4.FM 5-428 Chptr 6 Reinforced-Concrete Construction Figure 6-1. The concrete's shear strength is about one-third the unit compressive strength. However.
(View 1 exaggerates possible cracking to show the beam condition if loaded sufficiently. the weak tension area shown in view 1 of Figure 6-3 must be reinforced with steel as shown in view 2. Creep or plastic flow is the tendency for loaded concrete members to deform after time. Deformed steel-reinforced bars BENDING STRENGTH 6-7.FM 5-428 Chptr 6 Reinforced-Concrete Construction Figure 6-2. Therefore.) The concrete in the compression areas usually does not require reinforcement. Creep occurs over the whole stress range. becoming small or negligible after a year or two. Some experts believe that the first few service loads remove the initial strains on well-designed. rapidly at first. A beam subjected to a bending moment deflects because its compression side shortens and its tension side lengthens. you cannot predict concrete 6-3 . Figure 6-3. then much more slowly. reinforced-concrete structures and if they are not overloaded. they will respond elastically. Because of creep. Concrete beams subjected to vertical load without and with steel reinforcement CREEP 6-8.
you cannot always trace failures to creep. This manual does not attempt to cover how to design reinforced-concrete structures or members because there are many authoritative texts available in this field. Structural members include beams. walls. engineers refer to standard specifications. girders.FM 5-428 Chptr 6 Reinforced-Concrete Construction deflection with any satisfactory degree of accuracy using the common deflection formulas. The expression "to design a beam" means to determine the size of a beam and the materials required to construct a beam that can safely support specified loads under specific conditions of span and stress. Reinforced-concrete structures consist of many types of reinforced structural members. This is shown as line N-A in Figure 6-1. because it usually disappears in well-proportioned structures before too much deflection occurs. STRUCTURAL MEMBERS REINFORCEMENT 6-14. The practical experience of many structural engineers combined with comprehensive tests and investigations conducted at universities and elsewhere. provide the solutions to many common problems in reinforced-concrete design. REINFORCED-CONCRETE DESIGN 6-11. However. For most practical designs. columns. HOMOGENOUS BEAMS 6-9. BASIS OF DESIGN 6-13. such as steel or timber beams. spacing. NEUTRAL AXIS 6-10. thus forming a monolithic whole. Homogeneous beams are nonreinforced beams composed of the same material throughout. 6-4 . and arrangements of reinforcing steel are the main factors that influence the design. SPECIFICATIONS 6-12. The design of a reinforced-concrete structure consists mainly of predicting both the position and direction of potential tension cracks in concrete and in preventing the cracks by locating sufficient reinforcing steel across their positions. TYPES OF STRUCTURAL MEMBERS 6-15. Each of these different structural members interacts with one another to a considerable degree. footings. The neutral axis is the plane in a beam where the bending stress equals zero. Economy in the use of materials and efficiency in strength. SECTION II. and slabs.
Figure 6-4 shows four common shapes of reinforcing steel for beams. The reinforcing bars of continuous beams continue across the intermediate supports to resist top tension in the support area.FM 5-428 Chptr 6 Reinforced-Concrete Construction BEAM REINFORCEMENT 6-16. Devices called bolsters or high chairs (see Figure 6-5) usually support the horizontal reinforcing bars and hold them in place during construction. Add stirrups or U-shaped bars when the bent-up bars cannot resist all the diagonal tension. Typical shapes of reinforcing steel for beams 6-5 . The purpose of a high chair is to ensure that rebar does not rest on the earth or vapor barrier. Two types of beam reinforcements are-q Stirrups. but instead is suspended inside the concrete beam where it is more effective and protected from moisture. This is where the inclined portion of a bent-up bar is placed to resist diagonal tension. Select metal highchairs for two or more levels of rebar or when workers will be required to walk on the robber during placement. Select high chairs with skids for use on vapor barrier or wet subbase. Stress-carrying reinforcing bars must be placed according to the ACI Code 318-83. The purpose of both the straight and bent-up bar is to resist the bending tension in the bottom of a beam that is over the central portion of the span. they pass under the bottom bar and are inclined or perpendicular to it to prevent lateral slippage. q Bolsters or high chairs. Because of the tensile stress on the stirrups. A beam requires fewer bars near the ends of the span where the bending moment is small. Figure 6-4.
All eight bars are located around the column periphery to resist bending. Supports for horizontal reinforcing steel COLUMN REINFORCEMENT 6-17. A column is a slender vertical member that carries a superimposed load unless its height is less than three times its least lateral dimension. Four vertical reinforcing bars help to carry the direct axial load as the column shortens under load. Figure 6-6 shows two types of column reinforcement. This mainly provides intermediate lateral support for the vertical 6-6 . see view 1 of Figure 6-6. the vertical member is called a pier or pedestal. Lateral reinforcement consists of individual ties or a continuous spiral that surrounds the column. These reinforcements are discussed below: q Vertical reinforcement. Allowable column loads and minimum column dimensions are governed by ACI Code 318-83. In that case. A loaded-concrete column shortens vertically and expands laterally. while another four serves as intermediate vertical reinforcement. Vertical reinforcement is the main type. q Lateral reinforcement.FM 5-428 Chptr 6 Reinforced-Concrete Construction Figure 6-5. Concrete columns must always have steel reinforcement because they are subject to bending.
A spiral column is a round column that has a continuous spiral winding of lateral reinforcement (see view 2 of Figure 6-6) encircling its core and vertical reinforcing bars to restrain expansion. the square concrete shell would bulge and crack. and the number of vertical bars for a spiral column. The cross-sectional area of the metal core cannot exceed 20 percent of the gross column area. the tie size. Composite and combination columns. A structural steel column that's encased in concrete at least 2 1/2 inches thick overall and reinforced with welded-wire fabric is called a combination column. The design engineer specifies the pitch of the spiral. The spiral reinforcement is superior to the many imperfect anchorages that are at the ends of the individual lateral ties in a tied column. A tied column is when lateral ties (see Tl Figure 6-6) restrain the expansion. A second system of ties (see T2 in the cross section of view 1 in Figure 6-6) confines the four intermediate vertical reinforcing bars to prevent the eight-bar group from tending to form a slightly circular configuration under load. Spiral columns. A round column has obvious advantages in this respect. and the column would fail.FM 5-428 Chptr 6 Reinforced-Concrete Construction q q reinforcement. 6-7 . Without the second system of ties. The pitch of the spiral reinforcement can be reduced to provide more effective lateral support. A composite column is a structural steel or cast-iron column thoroughly encased in concrete and reinforced with both vertical and spiral reinforcements. The vertical bars bulge outward in the direction of least opposition. A spiral column is generally considered to be stronger than a tied column. Composite and combination columns are often used in constructing large buildings. They need lateral reinforcement to hold them securely--at close vertical intervals--and too restrain the expansion.
in some cases.FM 5-428 Chptr 6 Reinforced-Concrete Construction Figure 6-6. chemical reaction. Slabs and walls are reinforced both vertically and laterally. this movement tends to cause tension stress in the concrete. as required by the specifications SECTION III. The amount of lateral reinforcement usually provided is approximately one-fifth of 1 percent of the cross-sectional area of the concrete. Depending on how much disturbance adjacent construction creates. REINFORCING STEEL 6-8 . Reinforcing concrete columns SLAB AND WALL REINFORCEMENT 6-18. The lateral reinforcement in the form of wire mesh resists reduction in concrete volume due to drying. The vertical reinforcement counteracts applied loads. cooling and.
65 13. Minimum-yield strengths are: 40.044 2.128 1. Table 6-1.000 psi.303 5.20 0. Bars are available in 11 sizes designated by numbers (see Table 6-1) that range in size from 3/8 inch to about 2 1/4 inches in diameter.00 1. DESIGNATIONS. The engineer specifies the sizes.500 0.000 1. Reinforcing steel is specified in ASTM A615. 60.FM 5-428 Chptr 6 Reinforced-Concrete Construction GRADES.178 1.79 1.625 0.410 1.30 0. GRADES 6-20.544 3.571 1. 50.000 psi.27 1.313 7.670 3. amounts.043 1. and A617. and 75. AND METHODS 6-19. in Inches 3 4 5 6 7 8 9 10 11 14 18 0.400 4.090 NOTE: The nominal dimensions of a deformed bar are equivalent to those of a plan round bar having the same weight per foot as the deformed bar.60 0.257 0.750 0.375 0.668 1. The main types of reinforcing steel are vertical and horizontal bars (see Figure 6-4) wire for tying columns (see Figure 6-6).11 0.000 psi.990 4. in Square Inches Perimeter.356 2.693 2. and wire mesh for shrinkage and contraction reinforcement of slabs and walls.376 .25 4.44 0.430 5.320 7.00 1.000 psi.749 3. Standard steel reinforcing bar Bar Designation Number* Unit Weight. in Pounds per Foot . in Inches Area.875 1. *Bar numbers are based on the number of eighths of an inch included in the nominal diameter of the bars (example: a number 3 bar is 3/8 inch in diameter).502 2.270 1.60 Diameter.56 2.963 2. and classifications of reinforcing steel to be 6-9 .142 3. A616.
The bars have a small. Table 6-2 gives the minimum concrete cover that must be provided for different types of reinforcement under varying conditions. called protective concrete. continuous. bar size. longitudinal grade line running between the main longitudinal ribs to identify 60. and steel type symbols. The two adopted grade-marking systems are shown in Figure 6-7. Number System. The latest ASTM specifications require permanent rolled-on identification because so many grades of steel reinforcing bars have the same deformation pattern. However. but the steel in reinforcing bars is ductile so that you can generally cold-form hooks of relatively small radius on the job without breakage. Table 6-2. the improved deformed bars (rebars) that conform to ASTM specifications are so superior in bonding value that hooking their ends does not add much strength. Wire mesh is cold-drawn from hard-grade steel. sides.000 psi.000 psi. Figure 6-7.FM 5-428 Chptr 6 Reinforced-Concrete Construction used. A rolled-on grade number follows the producing mill. q q Continuous Line System. Minimum concrete cover requirements for steel reinforcement 6-10 . and the number 60 identifies 60. Bolsters or high chairs (see Figure 6-5) are available in many heights to fit almost any requirement. The number 40 identifies 40.000 psi. Reinforcing bar grade-marking systems BOLSTERS OR HIGH CHAIRS 6-21. the number 50 identifies 50. They support the reinforcing steel and hold it a specified distance away from the exterior concrete shell poured around them. and tops of rebar.000 psi. Cover must be provided for the bottom.
Hooks should be fabricated to meet dimensional requirements stated in Table 6-3 below. Stirrups (see Figure 6-4) help bent bars to resist diagonal tension. it is somewhat troublesome. because they can be welded at any angle parallel to the diagonal stress. Vertical stirrups are anchored in different ways: by welding to or hooking tightly around longitudinal reinforcement or by embedding them sufficiently above a beam's midline so that they develop the required bond. STIRRUPS 2 1 1/2 1 1/2 3/4 1 1/2 4 6-22. They are one of the most practical methods of web reinforcement because they are easy to arrange and set in the forms with the other bars. walls. as well as to reinforce the beam web to keep cracks from spreading. This work is not only expensive. stirrups. 6-11 . ties. spirals Concrete exposed to salt water Adapted from ACI 318-83. Welded stirrups are more efficient than vertical ones. columns: Primary reinforcement. Vertical stirrups pass underneath the bottom steel and are perpendicular to it to prevent lateral slippage.FM 5-428 Chptr 6 Reinforced-Concrete Construction Forms Minimum Cover. joist: #14 and #18 bars #11 bar and smaller Beams. practical considerations offset this advantage. Inclined stirrups must be welded to longitudinal reinforcements on-site to prevent slippage and displacement during concrete placement. in Inches 3 Concrete cast against and permanently exposed to the earth Concrete exposed to the earth or weather: #6 through #18 bars #5. W31 or D31 wire and smaller Concrete not exposed to weather nor in contact with the earth: Slabs. However. At least one stirrup must cross every potential diagonal tension crack.
splice them together for longer runs. Lapping the bars (see Figure 6-8 below) allows bond stress to transfer the load from one bar to a second bar. If one bar is not long enough for the span. Table 6-4 below lists the recommended lap for particular bar designation numbers. depending on bar size. but the length is about 24 to 36 bar diameters. Recommended end hooks (all grades) Bar Size Number D* 180o Hooks A or G 2 4 5 6 7 8 9 10 11 14 18 2 1/4" 3" 3 3/4" 4 1/2" 5 1/4" 6" 9 1/2" 10 3/4" 12" 18 3/4" 24" 5" 6" 7" 8" 10" 11" 13" 15" 17" 23" 30" J 3" 4" 5" 6" 7" 8" 11 3/4" 11 1/4" 12 3/4" 19 3/4" 24 1/2" 90o Hooks A or G. Reinforcing bars are available only in certain lengths. Although you could hook the bars. Note 6-12 . SPLICES 6-23. 6" 8" 10" 12 14" 16" 19" 22" 24" 31" 41" *D = Finished bend diameter. never butt reinforcing bars. Engineering design dictates the actual length of the lap after considering the anticipated beam stresses.FM 5-428 Chptr 6 Reinforced-Concrete Construction Table 6-3. it is not always practical nor even desirable to bend them. A common way to splice bars is to lap them. PRINCIPLES 6-24.
000 Top All Bars Others 21 20 f'c = 5. and never splice bars at the points of maximum bending. Method of splicing reinforcing bars Table 6-4. Except as shown on plans. Every bar requires at least two supports with bolsters spaced at about 5-foot intervals. Minimum splice overlap Overlap in Inches f'c = 3.000 Bar Size in Number 3 f'c = 4. stagger the splices so that they all do not fall at the same point. do not splice steel reinforcement without the approval of an engineer. Figure 6-8.000 Top All Bars Others 21 20 Top All Bars Others 21 20 6-13 .000 Top All Bars Others 21 20 f'c = 6. It is usually best to locate splices beyond the center of the beam.FM 5-428 Chptr 6 Reinforced-Concrete Construction that the minimum lap for plain bars is twice that for deformed bars. When possible.
Although lapping bars in a vertical plane. Lapping bars in a horizontal plane. Other such coatings include oil. Do not use this method-q In a beam. the top bars will not fit the stirrups properly.FM 5-428 Chptr 6 Reinforced-Concrete Construction 4 5 6 7 8 9 10 11 29 36 46 63 82 104 132 163 20 26 33 45 59 74 95 116 29 36 43 54 71 90 115 141 20 26 31 39 51 65 82 101 29 36 43 50 64 81 103 126 20 26 31 36 46 58 73 90 29 36 43 50 58 74 94 115 20 26 31 36 42 53 67 82 NOTES: 1. Both this method and the one shown in view 3 of Figure 6-8 facilitate tying the bars to hold them in position during concreting. particularly heavy corrosion caused by previous outdoor storage. Top bars are defined as horizontal bars with 12 or more inches of fresh concrete placed below. and weak dried mortar. This data is recommended for normal-weight concrete. permits better encasement. shown in view 3 of Figure 6-8. CARE 6-26. If the mortar is difficult to remove. in fact. if the spacing provides enough clearance for the aggregate to pass. A thin film of rust or mill scale is not seriously objectionable either. paint. dried mud. q With similar members having several closely spaced bars. remove any objectionable coating from the steel. grease. The splicing method shown in view 1 of Figure 6-8 above is satisfactory when bar spacing is large. tying does not add much to splice strength and creates possible problems of air pockets and poor bond in the space under the bar overlap. This informatiion is based on a class C splice (ACI 318-83). However. is the most practical arrangement. q When form filling. Before storing outdoors. these bars would probably be locked into the positions shown in view 2 of Figure 6-8. it can increase the bond 6-14 . In practice. and the beam will have a smaller effective depth at one location than at another. q When the overlapped section interferes with proper bar covering. shown in view 2 of Figure 6-8. METHODS 6-25. leave it. 2. Care must be taken to prevent reinforcing steel from rusting too much during outdoor storage.
Make bends around pins whose diameters are not less than six times the bar diameter (see Table 6-1). cover the steel to protect it from weather.by 1 1/2. use a hickey (a lever for bending bars) or a bar-bending table like the one shown in Figure 6-9. anything that destroys the bond between the concrete and the steel can create serious problems by preventing the stress in the steel from performing its function properly. it is better to bend steel bars greater than 3/8 inch in diameter on a bar-bending machine. After cleaning. For these bar diameters. However. Remove all loose rust or scale by rubbing the steel with burlap or other similar means. then sawing a section from one side of the tee. except for hooks and straight bars larger than 1 inch in diameter.FM 5-428 Chptr 6 Reinforced-Concrete Construction between the steel and concrete. Remember. Bar bending table 6-15 . except for bars more than 1 1/8 inch in diameter. the minimum bending pin diameter should be eight times the bar size.by 2-inch pipe tee section to the end of a 1 1/4-inch pipe lever that is 3 feet long. You can usually cold-bend stirrups and column ties that are less than 1/2 inch in diameter. as well as steel bars no larger than 3/8 inch in diameter. It is possible to improvise a hickey by attaching a 2. Large numbers of reinforcing bars can be prefabricated on the job to the varied lengths and shapes shown on the drawings. If possible. Figure 6-9. be aware that the bends these devices make are usually too sharp and weaken the bar. Heating is not usually necessary. ON-SITE PREFABRICATION 6-27.
Be sure to use enough supports and spacers to hold the steel firmly. and floor slabs is not less than 1 1/3 times the largest size aggregate particle in the concrete. and secure all bars to supports and other bars using tie wires not smaller than 18 gage. the minimum clearance between parallel bars in beams. eventually creating a pathway for water to penetrate and degrade reinforcing rebar. First. even when subjected to construction loads. wires. SPACERS 6-30. Never use rocks. metal bolsters and chairs. FLOOR SLABS 6-32. you can use spacer blocks made from sand-cement mortar as described above. All steel reinforcement must be accurately located in the forms and held firmly in place both before and during concreting. but no CA. tie the column steel together and position it as a unit. wood blocks. The aggregate must not become lodged between the form and reinforcing steel. footings. 6-16 . Twisted-tie ends should project away from an interior surface to avoid contact with the concrete surface. use built-in concrete blocks. Figure 6-10 shows a typical arrangement of reinforcing steel in a floor slab. To meet such specifications. Then erect the column form around the unit and tie the reinforcing steel to the form at 5-foot intervals. SUPPORT 6-29. as well as retain it at the proper distance from the forms. make spacer and supporting blocks from mortar having the same consistency as the concrete. The minimum clearance between parallel bars in columns is not less than 1 1/2 times the bar diameter. walls.FM 5-428 Chptr 6 Reinforced-Concrete Construction PLACEMENT 6-28. Cast tie wires into the blocks to secure them to the reinforcing bars. Wood blocks deteriorate. Minimum clear space between reinforcing steel and concrete forms must also be checked with the MSA in the concrete mix design. spacer bars. varying in length as required. or other devices that prevent steel displacement during construction. but in no case less than 1 inch. Do not remove this type of spacer block when placing the concrete. Instead of the bolster. Some specifications state that no metal be left in concrete within a certain distance of the surface. The required thickness of the concrete protective cover determines the height of the bolster. preventing passage by any further concrete. Hold the bars firmly in place by tying the intersections together at frequent intervals with one turn of wire. Generally. or other unapproved supports. COLUMNS 6-31. Support horizontal bars at minimum intervals of 5 or 6 feet. Spacer blocks are usually 1 1/2 inch square or larger. To do this.
6-17 . Note that the stirrups pass under the main reinforcing bars and are tied to them with one turn of wire. Figure 6-11 shows the position of bolsters and stirrups with the reinforcing bars in a reinforced-concrete beam.FM 5-428 Chptr 6 Reinforced-Concrete Construction Figure 6-10. Reinforcing steel arrangement for a floor slab BEAMS 6-33.
from top to bottom. but its primary use is to control crack widths due to temperature changes. erect the reinforcing steel for concrete walls in place.FM 5-428 Chptr 6 Reinforced-Concrete Construction Figure 6-11. Place reinforcing steel for footings as shown in view 3 of Figure 6-12. walls. You can remove the wood blocks after you fill the forms to block level. and slabs. Use spacer bars to support the steel above the subgrade to the proper distance. Unless you are using wire-mesh fabric. 6-18 . Do not preassemble it as you do for columns. Use ties between the bars. Beam reinforcing steel WALLS AND FOOTINGS 6-34. for high walls (see view 1 of Figure 6-12). Welded-wire fabric (see view 2 of Figure 6-12) is also used as limited reinforcement for concrete footings.
Precast concrete is concrete cast in other than its final position. Prestressed concrete is a combination of high-tensile steel and 6-19 . precast concrete requires field connections to tie the structure together. The connections can be a major design problem. Wall and footing reinforcement SECTION IV. The compressive stresses counteract the stresses that occur when a unit is subjected to loads. Unlike cast-in-place concrete. job-site precasting is common on large projects and in area's remote from a precasting source. PRECAST CONCRETE DEFINITION AND CHARACTERISTICS 6-35. Although precasting is best suited to a manufacturer's factory or yard. Nearly all prestressed concrete is precast. DEFINITION 6-36.FM 5-428 Chptr 6 Reinforced-Concrete Construction Figure 6-12. Prestressed concrete is subjected to compressive stresses before any external loads are applied.
Short members. then jacking or lifting them one upon another to their final positions. because you do not have to support the forms on scaffolding. Many firms do not maintain facilities for prestressing or special surface treatments that you may require. Form costs are much less with precast concrete. Precast concrete tends to be a local business. then tilted up to its final. either by pretensioning or posttensioning (stretched before or after pouring the concrete). curbing. ribbed panels. posts. Prestressing these panels makes it possible to handle and erect large units and thin sections without cracking. Precast-reinforced slabs are also available for curtain walls in buildings having either steel or concrete frames. wire strands. that must be wear-resisting. In tilt-up. single and double tees. But a thin wall is easily precasted flat on the ground. few deliver more than 200 to 300 miles from their facility. water tanks. flooring. the wall is cast horizontally. precast concrete products fall roughly into five groups. and troughs. natural stone-faced panels. simply set the forms on the ground in a convenient position. Thus. inverted T-beams. precast floor and roof units are usually prestressed with tongue-and-groove edges and special clips to anchor them to supporting members. vertical position. Units range from 16 to 96 inches wide and from 4 to 12 inches deep. solid panels. columns. and I-beams. Hollow-core slabs may have grouted shear keys to distribute loads to adjacent units over a slab width as great as one-half the span. highway girders. ADVANTAGES 6-39. Prestressing is accomplished by stretching the high-strength steel wire. q Load-bearing structural members (beams. A thin concrete wall is very difficult to construct if cast vertically. decorative panels. For this reason. Check those manufacturers who will deliver to the project area to find out what is available. L-shaped beams. hollow-core slabs. because the concrete must be poured high up in the narrow opening at the top of the form. there is a wide variation in the types and sizes of precast items available in different areas. sandwich panels. CHARACTERISTICS 6-37. Long-span.FM 5-428 Chptr 6 Reinforced-Concrete Construction high-strength concrete. lintels. rectangular beams. bricks. Such wall panels include plain panels. the large-side forms are eliminated. 30 feet or less. Hollow-core slabs are usually available in normal or structural lightweight concrete. masts. and so forth. Although there are many manufacturers. are often made with ordinary steel reinforcement. pipes. as well as the braces that hold a 6-20 . Many of these units are prestressed. Two other convenient forms of precast concrete are tilt-up and lift-slab that save formwork expense since wall and floor surfaces are cast horizontally at a convenient level. load-bearing and nonload-bearing panels. Available types of precast floor and roof units include solid or ribbed slabs. roofing) and other standard units such as piles. q Concrete blocks. Lift-slab involves precasting the floor and roof slabs of a multistory building horizontally. paving flags. q Architectural cast stone and other type of ornamental concrete. q Steps. q Roofing units and tiles that must be waterproof and weather-resistant. electric poles. In general. or bars. PRODUCT AVAILABILITY 6-38. and slabs. and thin-section panels.
Place the reinforcement (including pretensioning. fiberglass. along with the following: q Extra materials. The variety of shapes and designs available is limited only by the imagination and cost. architect or construction supervisor. Is a specialist available to supervise manufacture? Someone also has to coordinate the work and prepare the shop drawings. permanent precast units can often be used as a working platform. Great savings can result from repeated reuse of forms and assembly line production techniques. Precasting also takes plenty of space. Precast units can be standardized and mass-produced. The decision as to whether concrete is cast-in-place. q Manufacture. . . You can also maintain high quality control of precast products.CA and FA. . q Supervision. These costs must also be included. wood. q 6-21 . Extra labor.Reinforcement. thus eliminating the need for scaffolding. derricks and a specialty crew to set the pieces. Precast concrete requires large placing equipment such as cranes. However.Clean forms.FM 5-428 Chptr 6 Reinforced-Concrete Construction vertical form in place. . usually by truck. and so forth). Precast units poured on-site require minimal transportation. Precast concrete buildings are built so that all the structural concrete (except footings) is precast and put together piece by piece. . Such delays are common in cast-in-place construction. but any off-site precast concrete requires transportation. or a combination of materials? Who will make the forms? How long will manufacturing take? How much will it cost? The cost of the forms must also be charged to the precast items. Is enough space available on-site or should the material be precast off-site and transported to the job-site? If precasting is accomplished off-site. precasting on-site is not recommended unless experienced precast personnel are available to supervise the work. or precast on-site is made by the design engineer. DISADVANTAGES 6-40.Cement. Most are available in either reinforced or prestressed conditions. Materials must be purchased for-. . .Water. purchased precast. if required).Mix and place concrete (including troweling. Labor is required to-. In addition. the engineer must consider the following: q Special requirements. the necessary facilities and transportation costs must be added to the cost of the items precast. In some types of precast construction. you lose no time waiting for concrete to gain strength at one level before you can place the next. In making the decision.Apply oil or retarders to forms.Anchors and inserts. Should forms be made from steel.
6-22 .FM 5-428 Chptr 6 Reinforced-Concrete Construction . On-site or temporary prefabrication plants are suitable for military operations. and vibrators. although output will vary according to personal experience. Bridge T-beams. reinforced-concrete arches. the numbers required. . There are inherent problems to resolve in this type of construction such as provisions for seating members and tying the structure together.Uncover the concrete after initial curing. All equipment requires storage space. Figure 6-13 is a schematic layout of a prefabrication yard suitable for producing typical members. level ground that has ample working space and access routes. and concrete logs are precast structural members.Load and unload transport truck. and its use. and miscellaneous equipment such as hoes. if concrete is precast off-site. Table 6-5 below recommends the personnel requirements. derricks.000 square feet of precast walls per day.Erect the precast concrete on the job. Because the purpose of this chapter is only familiarization with the end products and the materials and methods used to produce them. hammers. When using precast members. You can expect such a prefabrication facility to produce approximately 6. q DESIGN 6-41. PREFABRICATION 6-42. Special equipment is required to prestress concrete. equipment to cure the concrete. Extra equipment. end walls. wheelbarrows. the accuracy of the building layout is extremely important. The yard must be on firm. .Strip the concrete from the forms and stockpile it to finish curing.Cover the concrete and apply the curing method. Lay out the prefabrication yard to suit the type and the quantity of members you will precast. equipment capabilities. Necessary equipment may include mixers. shovels. They are subject to prevailing weather and climate conditions because they have no roofing. neither the engineering nor design of precast concrete is discussed. The design of a structure composed of precast members requires both cleverness and engineering skill. lift trucks. and product requirements. You can precast structural members either in central off-site or on-site prefabrication plants depending upon the product. The precast pieces must fit together like a jigsaw puzzle leaving little room for error. cranes. . .
Schematic layout of on-site or temporary prefabrication yard for military operations Table 6-5.FM 5-428 Chptr 6 Reinforced-Concrete Construction Figure 6-13. cement. curing and finishing Placing reinforcement Refurbishing forms Personnel 1 NCO 4 EMs 2EMs 2 NCOs 13 EMs Mixing 1 NCO Water. Recommended precasting team personnel requirements Area Reinforcement shops and steel storage Workshop Casting. Storage 5 EMs 6-23 . and aggregate.
Use spreader bars to handle the elements at their correct pickup points. all members require adequate support so that they do not undergo either strain or loading greater than the design loading. but must be protected from too much bending stress caused by their own dead weight. ERECTION 6-44.FM 5-428 Chptr 6 Reinforced-Concrete Construction Product stockpiles Loading and distribution 2 EMs TRANSPORTATION 6-43. Erecting precast members is similar to erecting reinforcing steel and requires cranes or derricks of sufficient capacity. Smaller members can be transported (columns. Various types of hauling and handling equipment are needed in precast concrete operations. Sometimes two cranes or derricks are needed to lift very long or heavy members. 6-24 . slabs) on flatbed trailers. Precast members can withstand farther hauling and rougher treatment then either plain or reinforced members. You can transport heavy girders long distances on tractor trailers or with a tractor and dolly arrangement in which the girder acts as the tongue or tie between the tractor and the dolly. piles.
As time continued. tying. that consist of units held together with mortar. bricks. MASON'S TOOLS AND EQUIPMENT DEFINITION 7-3. They are also responsible for the correct mixing proportions of the mortar and the safe erection of scaffolding. properties. Masons are highly skilled people who use specialized equipment to lay out and construct masonry walls and other building features. bricks. concrete blocks. The characteristics of brick. construction procedures. Today. Many of the longest-lasting structures in the world are constructed with masonry materials. with improved quality and type of materials available. and mixing of mortar. or blocks. such as stones. The characteristics of masonry work are determined by the properties of the masonry units and mortar. anchoring. and rubble stone masonry. and the methods of bonding. gypsum blocks. and sometimes glass blocks. Along with erecting these structures. Chapter 7 Basic Equipment and Components General 7-2. and brick laying methods are discussed in the final chapter. this orderly lying of stone has progressed into laying them with the use of masonry cements that bonds them together. reinforcing. and joining the units into a structure. masonry means to build a structure from any building materials. clay tile products. SECTION I. Concrete masonry will include the characteristics of concrete blocks. Masonry originally meant the art of building a structure from stone. stones. Part two of this manual covers basic tools and equipment. 7-1 . such as. masons are responsible for the care of their tools and equipment. The original idea of masonry was nothing more than placing stones in an orderly fashion normally by laying them in rows.FM 5-428 Chptr 7 Masonry PART TWO Masonry 7-1.
Figure 7-2 shows a level in both the horizontal and vertical positions. and the middle portion of the top edge from 6 to 10 inches wide. As its name implies. wide trowels are best because they do not put too much strain on the wrist. and mortar tools clean because hardened mortar is difficult to remove. The mason's hammer has a square face on one end and a long chisel peen on the other. There are several different types of jointer-rounded. The middle portion of the top edge must be parallel to the bottom edge. to spread mortar. wheelbarrows. q A mason's level. q A straightedge. can be any length up to 16 feet. A trowel is used to mix and pick up mortar from the board. this tool is used to make various mortar joints. the masonry is plumb. A full set includes-q A trowel. or pointed. A chisel is used to cut masonry units into parts. Clean all tools and equipment thoroughly at the end of each day or when the job is finished. A level ranges from 42 to 48 inches in length and is made from either wood or metal. depending on the shape of the mortar joint you want. A common trowel is usually triangular in shape ranging in size up to about 11 inches long and from 4 to 8 inches wide. ranging from 3 to 6 inches long and 2 to 3 inches wide. chalk lines. mortar hoes. When you place the level against the masonry vertically and the bubbles fall exactly in the middle of the two end tubes. plumb bobs. q Miscellaneous tools. from 1 1/8 inches to 1 1/2 inches thick. Be sure to keep wheelbarrows. A straightedge. It weighs from 1 1/2 to 3 1/2 pounds. It is used to split and rough-break masonry units. short. 7-2 . to place mortar on the unit. Generally. Care of the tools are extremely necessary. When you place it on the masonry horizontally and the bubble falls exactly in the middle of the center tube. shown in Figure 7-2. Its length and weight depend on the mason. q A hammer. the masonry is level. Trowels used to point and strike joints are smaller. The square that is shown in Figure 7-2 below is used to measure right angles and to lay out corners.FM 5-428 Chptr 7 Masonry TOOLS 7-4. and to tap the unit down into the bed. Use a straightedge to extend a level to either plumb or level distances longer than the level length. Other mason's tools and equipment include shovels. flat. A typical chisel is 2 1/2 to 4 1/2 inches wide. The level is used to plumb and level walls. q A chisel or bolster. q A square. Figure 7-1 shows a set of typical basic mason's tools. q A jointer. and a 200-foot ball of good quality mason's line. mortar boxes.
FM 5-428 Chptr 7 Masonry
Figure 7-1. Basic Mason's Tools
7-5. Mortar is mixed by hand in a mortar box. It should be as watertight as possible. A mortar board (see Figure 7-3) can range from 3 to 4 feet square. Wet down a mortar board thoroughly before placing any mortar on it to prevent the wood from drying it out and absorbing moisture from the mortar. Figure 7-3 shows the proper way to fill a mortar board. Note the mounds of mortar in the center of the board; this minimizes drying. After filling the
FM 5-428 Chptr 7 Masonry
Figure 7-2. Square, mason's level, and straightedge
mortar board, keep the mortar rounded up in the center of the board and the outer edges of the board clean. Any mortar spread in a thin layer dries out quickly, and lumps form in it. Be sure to maintain the proper mortar consistency at all times.
FM 5-428 Chptr 7 Masonry
Figure 7-3. Motar Box and mortar board
FM 5-428 Chptr 7 Masonry
7-6. Good mortar is necessary for good workmanship and good masonry service because it must bond the masonry units into a strong well-knit structure. BOND CONSIDERATIONS 7-7. The mortar that bonds concrete blocks,bricks, or clay tiles together will be the weakest part of the masonry unless you mix and apply it properly. When masonry leaks are encountered, they are usually through the mortar joints. The strength of masonry and its resistance to rain penetration depends largely on the strength of the bond between the masonry unit and the mortar. Various factors affect bond strength including the type and quantity of mortar, its workability or plasticity, its water retentivity, the surface texture of the mortar bed, and the quality of workmanship in laying the units. You can correct irregular brick dimensions and shape with a good mortar joint. PLASTICITY 7-8. Mortar must be flexible enough to work with a trowel. You can obtain good plasticity or workability byq Using mortar having good water retentivity. q Using the proper grade of sand and thoroughly mixing. q Using less cementitious materials. Mortar properties depend largely upon the type of sand the mortar contains. Clean, sharp sand produces excellent mortar; too much sand causes mortar to segregate, drop off the trowel, and weather poorly. WATER RETENTIVITY 7-9. Mortar property resists rapid water loss to highly absorbent masonry units. Mortar must have water to develop the bond. If it does not contain enough water, the mortar will have poor plasticity and workability and the bond will be weak and spotty. Sometimes you must wet the brick to control water absorption before applying mortar, but never wet concrete masonry units. STRENGTH AND DURABILITY 7-10. The type of service that the masonry must give determines the mortar's strength and durability requirements. For example, walls subject to severe stresses or to severe weathering
FM 5-428 Chptr 7 Masonry
must be laid with more durable, stronger mortars than walls for ordinary service. Table 7-1 below gives mortar mix proportions that provide adequate strength and durability for the conditions listed. You can convert the unit volume proportions to weight proportions by multiplying the unit volumes given by the weight per cubic foot of the materials. Those specifications are-Masonry cement --------------------------- Weight printed on bag Portland cement ---------------------------- 94 lb Hydrated lime ------------------------------ 50 lb Mortar sand, damp and loose -------------- 85 lb Table 7-1. Recommended mortar mix proportions by unit volume Type of Services Cement Hydrated Lime Mortar Sand in Damp, Loose Conditions 2 1/4 to 3 4 1/2 to 6 4 1/2 to 6
1 unit masonry cement 1/2 to 1 1/4 or 1 unit portland cement
Isolated piers subjected to extremely 1 unit masonry heavy loads, violent winds, earthquakes, cement* plus 1 unit or severe frost action portland cement or 1 unit portland cement *ASTM specification C91 type II. TYPES OF MORTAR
0 to 1/4
2 1/4 to 3
7-11. The following mortar types are proportioned on a volume basis: q Type M mortar consist of one part portland cement, 1/4 part hydrated lime or lime putty and, 3 parts sand or 1 part portland cement, 1 part type II masonry cement, and 6 parts sand. Type M mortar is suitable for general use but is recommended specifically for below-grade masonry that contacts earth, such as foun-dations, retaining walls, and walks. q Type S mortar consist of one part portland cement, 1/2 part hydrated lime or lime putty, and 4 1/2 parts sand, or 1/2 part portland cement, 1 part type II masonry cement, and 4 1/2 parts sand. Type S mortar is also suitable for general use, but is recommended where high resistance to lateral forces is required. q Type N mortar consist of one part portland cement, 1 part hydrated lime or lime putty, and 6 parts sand, or 1 part type II masonry cement and 3 parts sand. Type N mortar is
FM 5-428 Chptr 7 Masonry
suitable for general use in above- grade exposed masonry where high compressive and/or lateral strengths are not required. Type O mortar consist of one part portland cement, 2 parts hydrated lime or lime putty, and 9 parts sand, or 1 part type I or type II masonry cement and 3 parts sand. Type O mortar is recommended for load-bearing, solid-unit walls when the compressive stresses do not exceed 100 psi, and the masonry is not subject to freezing and thawing in the presence of a lot of moisture.
STORING MORTAR MATERIALS 7-12. Store all mortar materials, except sand and slaked quicklime, in a dry place. Sand and lime should be covered to prevent excessive losses or gains of surface moisture.
7-13. When blending or mixing mortar, always use the best consistency for the job. MACHINE MIXING 7-14. Mix large quantities of mortar in a drum-type mixer, like a concrete mixer. Mix a minimum of 3 minutes. Place all dry ingredients in the mixer first, mix them for 1 minute before adding the water. HAND MIXING 7-15. Mix small amounts of mortar by hand in a mortar box (see Figure 7-3). Mix all ingredients thoroughly to obtain a uniform mixture. Mix all dry materials together first before adding water. Keep a steel drum of water close to the mortar box to use as the water supply. Use a second drum of water to store shovels and hoes when not in use. MORTAR MIXING WITH LIME PUTTY 7-16. When machine mixing, measure the lime putty using a pail and place it into the skip on top of the sand. When hand mixing, add the sand to the lime putty. Wet pails before placing mortar in them and clean them immediately after emptying them. WATER QUALITY 7-17. Mixing water for mortar must meet the same requirements as mixing water for concrete. Do not use water con-taining large amounts of dissolved salts, because the salts will cause efflorescence and weaken the mortar. RETEMPERING MORTAR 7-18. The workability of any mortar that stiffens on the mortar board due to evaporation by remixing can be restored. Add water as necessary, but discard any mortar stiffened by initial setting. It is difficult to tell the cause of stiffening; a practical guide is to use mortar within 2
Compact the joints thoroughly by tooling after the mortar partially stiffens. When you no longer need the planks at a lower level. Calcium chloride should not be used for steel-reinforced masonry. The planks should be made using 2 by l0s. Place the trestle at least 3 inches from the wall so that it does not press against the newly laid bricks and force 7-9 . remove them to avoid falling mortar splash. Use a trestle scaffold shown in Figure 7-4 when laying bricks from the inside of a wall. TRESTLE SCAFFOLD 7-24. Do not use an admixture to lower the freezing point of mortar during winter construction. ACCELLERATORS 7-20. The quantity of antifreeze materials necessary to lower the freezing point of mortar to any appreciable degree is so large that it would seriously impair the mortar's strength and other desirable properties. to accelerate its hardening rate and increase early strength. Never use frozen mortar. Extreme care should be taken in building scaffolds because lives depend on them. Do not add more than 2 percent calcium chloride. The height of the trestles should range from 4 to 4 1/2 feet. movable platform built with planks to support workers and materials. Do not add more than 1 percent calcium chloride to masonry cements.FM 5-428 Chptr 7 Masonry 1/2 hours after the original mixing when the air temperature is 80°F or higher. Scaffolds can be used in several functions and come in different sizes and heights. TYPES OF SCAFFOLDING 7-23. A scaffold is a temporary. SCAFFOLDING CONSTRUCTION AND SAFETY 7-22. always nail it securely. freezing destroys its bonding ability. REPAIRING AND TUCK-POINTING 7-21. Erect the scaffold when the wall reaches a height of 4 or 5 feet. and within 3 1/2 hours when the air temperature is below 80°F. ANTIFREEZE MATERIALS 7-19. It allows bricklayers to work at heights not reachable when standing on the floor or ground. Discard any mortar not used within these limits. Use rough lumber for wood scaffolding. Make a trial mix to find the percentage of calcium chloride that gives the desired hardening rate. Never nail scaffolding in a temporary manner. by weight of cement to mortar. You can also accelerate hardening rate in mortars with high-early-strength portland cement. Use the mortar mixes given in Table 7-1 when repairing and tuck-pointing old masonry walls. SECTION III.
Its uprights are 4 by 4s supported on a 2 by 12 by 12 plank for bearing on the soil. Trestle scaffold FOOT SCAFFOLD 7-25. repeat the procedure. When the rough flooring for the next floor is in place. A putlog scaffold (see Figure 7-6) reaches from the ground to the height required. Figure 7-5. When reaching lower than a trestle scaffold permits. Build the wall to the next floor level working from the scaffold. Space the 7-10 . A foot scaffold should not exceed 18 inches in height. Place 2 by 10 planks on blocks supported by the trestle scaffold. Figure 7-4. use a foot scaffold like the one shown in Figure 7-5. Foot scaffold PUTLOG SCAFFOLD 7-26.FM 5-428 Chptr 7 Masonry them out of line.
Two ways to use stays areq Tie the uprights to the wall with stays. Figure 7-6. Bring the other ends of the 2 by 6s together and nail them securely to the ledger. as shown in Figure 7-6. Putlog scaffold OUTRIGGER SCAFFOLD 7-27.FM 5-428 Chptr 7 Masonry uprights on 8-foot centers and allow 4 1/2 feet of space between the wall and the uprights. To make spring stays. q Use the putlog as a stay. Place five 2 by 12 planks on top of the putlog to form the scaffold platform. An outrigger scaffold (see Figure 7-7) consists of a wood outrigger beam projecting from a window sill that supports 2 by 10 planks. omit one brick from the wall and insert the ends of two 2 by 6s in the opening. Then insert a brick between the 2 by 6s and force the brick toward the wall. Install longitudinal cross bracing as shown in Figure 7-6. but if you use a steel outrigger beam. Do not fasten the putlog to the ledger. while the other end fits into the wall (one brick is omitted to make an opening for it). You can either pass the stays through a window opening and fasten them to the inside structure or use spring stays as shown in Figure 7-6. Then. The putlog is 3-by 4-inch lumber that spans the gap between the wall and the ledger. Figure 7-7 shows how to brace a wood beam. Do not nail the planks to the putlog. One end of the putlog rests on top of the ledger and against the 4 by 4 uprights. 7-11 . You can also use the putlog as a stay by driving a wood wedge above the putlog into its hole in the wall. nail the wedge to the putlog and nail the putlog to the ledger. fasten it to the structure's formwork using threaded U-bolts.
FM 5-428 Chptr 7 Masonry Figure 7-7. If it is available. 7-12 . Outrigger scaffold PREFABRICATED STEEL SCAFFOLD 7-28. use prefabricated steel scaffolding (see Figure 7-8) rather than building a scaffold.
Prefabricated steel scaffold MATERIALS TOWER 7-29. Construct the tower footing using two 2 by 12s. Then construct landings extending from the tower to the floors and scaffold platforms as needed. Locate the tower where you can bring materials to it over the shortest haul. placed under each 4 by 4 post. A clearance of 6 feet 8 inches is enough for scaffold platforms 5 feet wide. but far enough away from the structure to clear any external scaffolding. you can construct a wood tower to hoist materials to the working height. The height of the tower should extend at least 15 feet above the highest point where you need a landing. Use 2 by 10s or 2 by 12s for the landings.FM 5-428 Chptr 7 Masonry Figure 7-8. like the one shown in Figure 7-9. 7-13 . 2 feet long. Otherwise. Use a steel material tower if construction details are available because it is easier to erect and generally safer.
FM 5-428 Chptr 7 Masonry Figure 7-9. Materials tower and elevator 7-14 .
Note the guides at the base of the elevator that fit onto the guides running up from the base of the tower. Figure 7-9 also shows the elevator. rope. and pulley arrangement that serves the materials tower.FM 5-428 Chptr 7 Masonry ELEVATOR 7-30. 7-15 .
water. and acoustics. gravel. economy. crushed stone. But today the term covers all types of concrete blocks (both hollow and solid) made with any kind of aggregate. the pieces thus formed are known as unit masonry. and offers an incomparable beauty and range of effect. compressive strength. and certain other special characteristics. coal cinders. and scoria (refuse obtained from metal ore reduction and smelting). durability. Construction of concrete masonry is time consuming and requires highly skilled personnel. and suitable aggregates. safety. Although a concrete block is made in many sizes and shapes (see Figure 8-1 below) and in both modular and nonmodular dimensions. SECTION I. durable. When portland cement. All concrete blocks must meet certain specifications covering size. pumice. air-cooled slag. The term concrete blocks was formerly limited to only hollow masonry units made with such aggregates as sand. including fire prevention. comfort.by 8. utility. gravel. expanded shale or clay. They are typically used for house foundations.FM 5-428 Chptr 8 Concrete Masonry Chapter 8 Concrete Masonry 8-1. crushed stone. and crushed stone. its most common unit size is 7 5/8 by 7 5/8 by 15 5/8.by 16-inch block nominal size. gravel. are mixed and formed into individual pieces to be used in laying up walls and other structural details. and a wide variety of surface textures. appearance. 8-1 . However. or slag. A concrete block is a masonry unit that either contains single or multiple hollows. decorative blocks for strong garden. Concrete blocks are also available with applied glazed surfaces. including sand. or retaining walls. moisture content. volcanic cinders (pozzolan). various pierced designs. most masons refer to them as concrete blocks. Concrete blocks will vary in size and shape as well as style. CHARACTERISTICS OF CONCRETE BLOCK NATURE AND PHYSICAL PROPERTIES 8-2. Properly designed and constructed concrete masonry walls satisfy many building requirements. burned shale. or is solid. Concrete masonry is an increasingly important type of construction due to technological developments in both the manufacture and the use of concrete blocks. Rubble stone masonry is strong. cinders. such as sand. It is made from conventional cement mixes and various types of aggregate. weight. known as 8. or units. type. expanded slag.
Typical unit sizes and shapes of concrete masonry units 8-2 .FM 5-428 Chptr 8 Concrete Masonry Figure 8-1.
q Fireproofing over structural members. Concrete blocks are used in all types of masonry construction. stones. and other facings. q Interior load-bearing walls. 8-3 . Typical unit sizes and shapes of concrete masonry units (continued) CONCRETE BLOCK MASONRY UNIT 8-3.FM 5-428 Chptr 8 Concrete Masonry Figure 8-1. q Fire walls and curtain walls. and enclosures. q Backing for bricks. q Partitions and panel walls. q Fire-safe walls around stairwells. such as-q Exterior load-bearing walls (both below and above grade). elevators.
a unit actually measuring 7 5/8 by 7 5/8 by 15 5/8 inches is called an 8. such as exterior walls both above and below grade that may or may not be exposed to moisture penetration or weather. load-bearing concrete block. nonload-bearing concrete block. 8-5. The grades are further subdivided into two types: type I moisture-controlled units (for use in arid climates) N-I and S-I. a hollow concrete block has a core area greater than 25 percent of its gross cross-sectional area--generally 40 to 50 percent. The concrete masonry units made with either heavyweight or lightweight aggregates are referred to as such. q Hollow. crushed stone. The load-bearing types of blocks have two grades. clay. The main types of concrete masonry units are-q Hollow. In contrast. load-bearing concrete block. 8-4 . gravel. SOLID AND HOLLOW UNITS 8-7. The same type and nominal-size block weighs only from 25 to 35 pounds when made with coal cinders. When laid with 3/8-inch mortar joints. Most concrete bricks are solid and sometimes have a recessed surface like the frogged brick shown in Figure 8-1 above. Concrete floor units.by 8. Concrete masonry units are available in many sizes and shapes to fit different construction needs. volcanic cinders. q Solid. Grade S is for above-grade exterior walls with weather-protective coating and for interior walls. q Concrete building tile. Grade N is for general use. HEAVYWEIGHT ANDF LIGHTWEIGHT UNITS 8-6. q Concrete brick. or air-cooled slag. Because concrete block sizes usually refer to nominal dimensions. load-bearing concrete block is 8 by 8 by 16 inches with nominal-size weight from 40 to 50 pounds. Retaining walls. or pumice. and for back-up and interior walls.by 16-inch block. A hollow.and half-length sizes are shown in Figure 8-1. TYPES OF UNITS 8-4. and type II nonmoisture-controlled units N-II and S-II.FM 5-428 Chptr 8 Concrete Masonry q q q q Piers and columns. Chimneys. slag. These types of blocks are normally made with heavyweight aggregate such as sand. ASTM specifications defines a solid concrete block as having a core area not more than 25 percent of the gross cross-sectional area. Your choice of masonry units depends on both availability and the requirements of the intended structure. Both full. expanded shale. SIZES AND SHAPES 8-8.
Before designing a structure. CURING CONCRETE BLOCKS 8-12. If steam is not available. MAKING WEATHER-EXPOSED BLOCKS 8-11. SECTION II. its components. When using lightweight. Modular coordination is when the design of a building. CONSTRUCTION PROCEDURES MODULAR COORDINATION AND PLANNING 8-13. it requires a large number of molds. This procedure makes dense block with little labor. porous aggregate. The modular system of coordinated drawings is based on a standard 4-inch grid placed on the width. contact local manufacturers for a schedule of their available unit sizes and shapes. cure the blocks by protecting them from the sun and keeping them damp for 7 days. as shown in Figure 8-2. then immediately strip off the mold. and the building-material units all conform to a dimensional standard based on a modular system. Tamp the concrete into the mold. however. premix it with water for 2 minutes before adding the cement. length. To precast blocks by hand. use a power-tamping machine available from several manufacturers. Modular measure is the system of dimensional standards for buildings and building components that permit field assembly without cutting. then strip off the molds when the concrete hardens. Make blocks subject to weathering with a concrete mix of at least six sacks of cement per cubic yards of mix. To precast concrete blocks. Concrete blocks cured in wet steam at 125o F for 15 hours have 70 percent of their 28-day strength. MAKING BLOCKS BY HAND 8-10. 8-5 . The basic unit is a 4-inch cube that allows a building to be laid around a continuous three-dimensional rectangular grid having 4-inch spacing. Steam is the best way to cure concrete blocks because it takes less time. This way you can make many blocks rapidly using a single mold.FM 5-428 Chptr 8 Concrete Masonry the unit will then occupy a space exactly 8 by 8 by 16 inches. The mix should be dry enough for the block to retain its shape. and height of a building. pour concrete of fluid consistency into sets of iron molds. MAKING BLOCKS BY MACHINE 8-9.
and half-length units when laying out concrete masonry walls to minimize cutting and fitting units on the job. for example. and locate them on or related to a grid line by reference dimensions. or to scale. time. Do not use drawing paper with a scale less than 3/4 inch which equals 1 foot to show grid lines at 4-inch spacing.FM 5-428 Chptr 8 Concrete Masonry Figure 8-2. Show materials actual size. and so forth. Remember that window and door frames must have modular dimensions to fit modular full. and preplan the work to make use of as many standard. and materials. 5 feet. Use the grid on preprinted drawing paper for both small-scale plans and large-scale details.and half-size masonry units.sized building materials as possible. Dimensions falling on grid lines are shown by arrows. Step 3. Elements of modular design Step 1. q q q q Maintain constant awareness of standard modular dimensions in planning. 6 feet 4 inches. by dots (see Figure 8-2 above). For floor plans and elevations. Both horizontal and vertical dimensions should be designed in multiples of 8 inches. Step 2. and corners to use full. the module may be 2 feet 8 inches. Keep all horizontal dimensions in multiples of nominal full-length masonry units. Table 8-1 below gives the nominal lengths of modular-concrete masonry walls in the number 8-6 . those not falling on grid lines.and half-size units as shown in Figure 8-3. Select a larger planning module that is a multiple of 4 inches. Make maximum use of full. and wall areas between doors. 4 feet. Such planning saves considerable labor. windows. Plan the wall length and height. the width and height of openings.
If the wall thickness is either greater or less than the length of one half-length unit. Planning concrete masonry wall openings Table 8-1. when using 8 by 4 by 16 blocks. Nominal length of modular-concrete masonry walls in stretchers Number of Stretchers Nominal Length of Concrete Masonry Walls Units 15 5/8" Long and Half Units 7 5/8" Long With 3/8" Thick Head Joints 1' 4" 2' 0" 2' 8" 3' 4" 4' 0" 4' 8" Units 11 5/8" Long and Half Units 5 5/8" Long With 3/8" Thick Head Joints 1' 0" 1' 6" 2' 0" 2' 6" 3' 0" 3' 6" 1 1 1/2 2 2 1/2 3 3 1/2 8-7 . Plan the horizontal dimensions in multiples of 8 inches (half-length units) and the vertical dimensions in multiples of 4 inches. use a special length unit at each corner in each course. Figure 8-3.FM 5-428 Chptr 8 Concrete Masonry q of stretchers. and Table 8-2 below gives the nominal heights of modular-concrete masonry walls in the number of courses.
Table 8-2.FM 5-428 Chptr 8 Concrete Masonry 4 4 1/2 5 5 1/2 6 6 1/2 7 7 1/2 8 8 1/2 9 9 1/2 10 10 1/2 11 11 1/2 12 12 1/2 13 13 1/2 14 14 1/2 15 20 5' 4" 6' 0" 6' 8" 7' 4" 8' 0" 8' 8" 9' 4" 10' 0" 10' 8" 11' 4" 12' 0" 12' 8" 13' 4" 14' 0" 14' 8" 15' 4" 16' 0" 16' 8" 17' 4" 18' 0" 18' 8" 19' 4" 20' 0" 26' 8" 4' 0" 4' 6" 5' 0" 5' 6" 6' 0" 6' 6" 7' 0" 7' 6" 8' 0" 8' 6" 9' 0" 9' 6" 10' 0" 10' 6" 11' 0" 11' 6" 12' 0" 12' 6" 13' 0" 13' 6" 14' 0" 14' 6" 15' 0" 20' 0" NOTE: Actual wall length is measured from outside edge to outside edge of units and equals the nominal length minus 3/8" (one mortar joint). Nominal height of modular-concrete masonry walls in courses Number of Stretchers Nominal Length of Concrete Masonry Walls 8-8 .
Height is measured from center to center of mortar joints. 8-9 .FM 5-428 Chptr 8 Concrete Masonry Units 7 5/8" High and 3/8" Thick Bed Joints 1 2 3 4 5 6 7 8 9 10 15 20 25 30 35 40 45 50 8" 1' 4" 2' 0" 2' 8" 3' 4" 4' 0" 4' 8" 5' 4" 6' 0" 6' 8" 10' 0" 13' 4" 16' 8" 20' 0" 23' 4" 26' 8" 30' 0" 33' 4" Units 3 5/8" High and 3/8" Thick Bed Joints 4" 8" 1' 0" 1' 4" 1' 8" 2' 0" 2' 4" 2' 8" 3' 0" 3' 4" 5' 0" 6' 8" 8' 4" 10' 0" 11' 8" 13' 4" 15' 0" 16' 8" NOTE: For concrete masonry units 7 5/8" and 3 5/8" in height laid with 3/8'' mortar joints.
Table 8-3.0 7 7 7 7 NOTES: 1. undisturbed soil having adequate load-bearing capacity to carry the design load and below frost penetration. M = cu ft of mortar for 100 sq ft of wall. in Lb* 2. Unless local requirements or codes specify otherwise. With face-shell mortar bedding.150 3. 2. *Actual weight within + 7% of average weight.350 5. in Lb* 3.FM 5-428 Chptr 8 Concrete Masonry WALLS AND WALL FOOTINGS 8-14.0 6.700 Lightweight Aggregate.950 2. Table is based on 3/8-inch mortar joints.600 4.500 7.700 Mortar.850 4. Actual weight of 100 sq ft of wall can be computed by formula W (n) + 150(M).5 9.0 6. 8-10 . in Inches For 100 Sq Ft of Walls Number of Units Average Weight of Finished Wall Heavyweight Aggregate. Place masonry wall footings on firm. Table 8-3 below gives both the unit weights and quantities for modular-concrete masonry walls.5 112.050 4. make the footings for small buildings twice as wide as the thickness of the walls they support.5 2.5 6 6 6 4 6 8 12 112.550 5. where-W = actual weight of a single unit.050 3. Mortar quantities should include 10% allowance for waste. in Inches Nominal Wall Thickness.900 6.5 112.5 9.5 112. n = number of units for 100 sq ft of wall.050 2. Unit weight and quantities for modular concrete masonry walls Actual Unit Size (Width x Height x Length).950 3.0 6.*in Cu Ft 3 5/8 x 3 5/8 x 15 5/8 5 5/8 x 3 5/8 x 15 5/8 7 5/8 x 3 5/8 x 15 5/8 3 5/8 x 7 5/8 x 15 5/8 5 5/8 x 7 5/8 x 15 5/8 7 5/8 x 7 5/8 x 15 5/8 11 5/8 x 7/5/8 x 15 5/8 4 6 8 225 225 225 9. Footing thickness equals wall width (see Figure 8-4 below).
use two continuous coatings of bituminous mastic brushed over a suitable priming coat. Step 1. When the first floor is in place. dry weather dampen the wall surface very lightly with a fog water spray before applying the first parging coat. Step 3. Place pieces of roofing felt over the joints to keep out sediment during backfilling. In hot. using either portland cement mortar (1:2 1/2 mix by volume) or joint mortar. Step 2. BASEMENT WALLS 8-16. If you expect the groundwater level during a wet season to reach the basement floor elevation. Always give exterior concrete masonry basement walls two 1/4-inch thick coats of parging. Make sure that the parging is dry before you apply the primer and that the primer is dry when you apply the bituminous mastic. For below-grade parged surfaces in very wet soils. The tile line should fall at least 1/2 inch in 12 feet and drain to a suitable outlet. Step 4. 8-11 . to provide a bond for the second parging coat. Cover the tile line to a depth of 12 inches with a permeable fill of coarse gravel or crushed stone ranging from 1 to 1 1/2 inches in size. Do not backfill against concrete masonry walls until the first floor is in place. then dampen it lightly just before applying the second coat. fill the balance of the trench with earth from the excavation. Keep the second coat damp for at least 48 hours following application.FM 5-428 Chptr 8 Concrete Masonry Figure 8-4. place a line of drain tile along the exterior side of the footings. Roughen the first coat when it is partly hardens. Dimensions of masonry wall footings SUBSURFACE DRAINAGE 8-15. Wait for the first coat to harden for 24 hours.
The first step in building a concrete masonry wall is to locate the corners of the structure. Step 3. and below cornices and other members that project beyond the wall face. Add flashing at vertical joints in copings and caps. If using blocks that are filled with mortar. and other projecting ledges. 8-12 . Lay each masonry unit plumb and true. Step 4. Use solid masonry courses to support floor beams or floor slabs to help distribute the loads over the walls as well as provide a termite barrier. Use either solid masonry units or fill the cores of hollow block with concrete or mortar. at the joints between the roofs and walls. Step 2. Good workmanship is a very important factor in building weathertight walls. Step 1. Shed water away from the wall surface by providing drips for chimney caps. Fill both horizontal and vertical joints completely. Then check the layout by placing the first course blocks without mortar (see Figure 8-5). compact them by tooling when the mortar partly stiffens. Make sure that drains and gutters are large enough so that overflowing water does not run down masonry surfaces.FM 5-428 Chptr 8 Concrete Masonry FLOOR AND ROOF SUPPORT 8-17. sills. WEATHERTIGHT CONCRETE MASONRY WALLS 8-18. lay strips of expanded metal lath in the bed joint underneath to support the fill. FIRST COURSE 8-19.
FM 5-428 Chptr 8 Concrete Masonry Figure 8-5. Step 2. Replace the loose blocks with a full bed of mortar. spreading and furrowing it with a 8-13 . Laying first course of blocks for a wall Step 1. Use a chalked snapline to mark the footing and align the blocks accurately.
Step 6.FM 5-428 Chptr 8 Concrete Masonry trowel to ensure plenty of mortar under the bottom edges of the first course. Place each block in its final position and push it down vertically into the mortar bed and against the previously laid block to obtain a well-filled vertical mortar joint. Leveling and plumbing first course of blocks for a wall Step 8. Step 7. Step 3. Apply mortar to the block ends for the vertical joints by placing several blocks on end and buttering them all in one operation. Make the joints 3/8 inch thick. Step 5. 8-14 . Step 4. Use the level to bring the blocks to proper grade and make them plumb by tapping with a trowel handle as shown in Figure 8-6. Figure 8-6. Lay the remaining first course blocks with the thicker end up to provide a larger mortar-bedding area. Use a mason's level after laying three or four blocks as a straightedge to check correct block alignment (see Figure 8-6). Use care to position and align the corner block first.
Lay each course at the corner. This ensures that succeeding courses and the final wall are both straight and true. and plumb. 8-15 . usually four or five courses high. Step 3. level. Apply mortar to the vertical joints either to the ends of the new block or the end of the block previously laid. After laying the first course. Step 1.FM 5-428 Chptr 8 Concrete Masonry Step 9. build up the corners of the wall next. to ensure well-filled joints (see Figure 8-7). Step 2. check it with a level for alignment for leveling and for ensuring that it is plumb (see Figure 8-8). Figure 8-7. Vertical joints Step 4. Move back each course one-half block. Apply mortar only to the tops of the blocks of the horizontal joints already laid. making sure that it is properly aligned. LAYING UP THE CORNERS 8-20. Lay out the first course of concrete masonry very carefully. or both.
FM 5-428 Chptr 8 Concrete Masonry Figure 8-8. Use care to check each block with a level or straightedge to make sure that all the 8-16 . Checking each course at the corner Step 5.
A story or course pole. Figure 8-9. Check the horizontal block spacing by placing a level diagonally across the corners of the blocks as shown in Figure 8-10. which is a board with markings 8 inch apart as shown in Figure 8-9 helps to accurately determine the top of each masonry course. straight walls. Using a story or course pole Step 6.FM 5-428 Chptr 8 Concrete Masonry block faces are in the same plane to ensure true. 8-17 .
tip it slightly toward you so that you can see the edge of the course below. Lay the top outside edge of each new block to this line (see Figure 8-11 below). 8-18 . Finally. Checking horizontal block spacing LAYING BLOCKS BETWEEN CORNERS 8-21. If any mortar falls out leaving an open joint. Step 1. Filling in the wall between corners CLOSURE BLOCK 8-22. q Place the lower edge of the new block directly on the edges of the blocks comprising the course below. because any adjustments you make after the mortar stiffens will break the mortar bond and allow water to penetrate. Figure 8-11. q First. Then lower the closure block carefully into place as shown in Figure 8-12.FM 5-428 Chptr 8 Concrete Masonry Figure 8-10. follow the procedures below. make all final position adjustments while the mortar is soft and plastic. When filling in the wall between the corners. How you grip a block before laying it is important. as shown in Figure 8-11. q q Next. remove the block and repeat the procedure. Before installing the closure block. Stretch a mason's line along the exterior block edges from corner to corner for each course. Step 2. butter both edges of the opening and all four vertical edges of the closure block with mortar. level each block and align it to the mason's line by tapping it lightly with a trowel handle.
FM 5-428 Chptr 8 Concrete Masonry Figure 8-12. and durable concrete masonry wall. do not spread mortar too far ahead of actually laying blocks or it will stiffen and lose its plasticity. Tooling compacts the mortar and forces it tightly against the 8-19 . cut off excess mortar extruding from the joints using a trowel (see Figure 8-13) and throw it back on the mortar board to rework into the fresh mortar. Do not. neat. To ensure a good bond. Cutting off excess mortar from the joints TOOLING 8-24. After laying a section of the wall. Figure 8-13. As you lay each block. The recommended width of mortar joints for concrete masonry units is approximately 3/8 inch thick which--when properly made--helps to produce a weathertight. tool the mortar joints when the mortar becomes thumbprint hard. rework any dead mortar from the scaffold or floor. Weathertight joints and the neat appearance of concrete masonry walls depend on proper tooling. however. Installing a closure block MORTAR JOINTS 8-23.
FM 5-428 Chptr 8 Concrete Masonry masonry on each side of the joint. Figure 8-14. Trim off mortar burrs from the tooling flush with the wall face using a trowel or soft bristle brush. Tooling mortar joints for weathertight exterior walls 8-20 . Use either concave or V-shaped tooling on all joints (see Figure 8-14). Tool vertical joints first. followed by striking the horizontal joints with a long jointer (see Figure 8-15 below). or by rubbing with a burlap bag.
You must prepare in advance for installing wood plates on top of hollow concrete 8-21 . Tooling mortar joints ANCHOR BOLTS 8-25.FM 5-428 Chptr 8 Concrete Masonry Figure 8-15.
place pieces of metal lath in the second horizontal mortar joint from the top of the wall under the cores that will contain the bolts. caulk them as well. 8-22 . Use anchor bolts 1/2 inch in diameter and 18 inches long. Control joints are continuous vertical joints that permit the masonry wall to move slightly under unusual stresses without cracking. The threaded end of the bolt should extend above the top of the wall as shown in Figure 8-16. rake it out to a depth of about 3/4 inch to make a recess for the caulking compound as shown in view 2 of Figure 8-17. When you complete the top course. A combination of full-and half-length blocks form the continuous vertical joint as shown in view 1 of Figure 8-17. insert the bolts into the cores of the top two courses. After the mortar is quite stiff. Lay up control joints in mortar just as any other joint. but if they are exposed to either the weather or to view. and fill the cores with concrete or mortar. The metal lath underneath holds the concrete or mortar filling in place. To do this. spacing them up to a maximum of 4 feet apart.FM 5-428 Chptr 8 Concrete Masonry masonry walls with anchor bolts. CONTROL JOINTS 8-26.
Installing anchor bolts for wood plates 8-23 .FM 5-428 Chptr 8 Concrete Masonry Figure 8-16.
Making a control joint Use a thin.FM 5-428 Chptr 8 Concrete Masonry Figure 8-17. You can make a second type of control joint by inserting building paper or roofing felt into the block end cores 8-24 . flat caulking trowel to force the compound into the joint.
Instead. BEARING WALLS 8-28. if available (see Figure 8-18). having a 2-inch right angle bend on each end (see Figure 8-19). INTERSECTING WALLS 8-27.FM 5-428 Chptr 8 Concrete Masonry extending the full height of the joint (see Figure 8-18). The paper or felt material prevents the mortar from bonding on that side of the joint. Do not join intersecting concrete block-bearing walls with a masonry bond. but wide enough to extend across the joint. Space the tie bars no more than 4 feet apart vertically. Use control joint blocks. Embed the right angle bends in the cores by filling them with mortar or concrete (see Figure 8-19) 8-25 . terminate one wall at the face of the second wall with a control joint. Tie the intersecting walls together with Zshaped metal-tie bars 1/4 by 1 1/4 by 28 inches in size. except at the corners. Cut the paper or felt to convenient lengths. The two types of intersecting walls are bearing and nonbearing. and place pieces of metal lath under the block cores that will contain the tie-bar ends (see Figure 8-16).
Control joints made using roofing felt or control joint blocksVertical joints 8-26 .FM 5-428 Chptr 8 Concrete Masonry Figure 8-18.
Insert one half of the metal strips into one wall as you build it. terminate one wall at the face of the second with a control joint. Tying intersecting bearing walls NONBEARING WALLS 8-29.FM 5-428 Chptr 8 Concrete Masonry Figure 8-19. tie the other halves into mortar joints as you lay the second wall 8-27 . To join intersecting nonbearing block walls. Place strips of metal lath or 1/4-inch mesh galvanized hardware cloth across the joint between the two walls in alternate courses.
FM 5-428 Chptr 8 Concrete Masonry Figure 8-20. Tying intersecting nonbearing walls 8-28 .
8-29 . Fill the joints tightly at the ends of the sills with mortar or a caulking compound. Use precast concrete lintels that contain an offset on the underside to fit the modular openings or use steel-lintel angles that you install with an offset on the underside (see Figure 8-21) to fit modular openings. Modular door and window openings usually require lintels to support the blocks over the openings. SILLS 8-31. In either case.FM 5-428 Chptr 8 Concrete Masonry LINTELS 8-30. Install precast concrete sills following wall construction (see Figure 822). place a noncorroding metal plate under the lintel ends at the control joints to allow the lintel to slip and the control joints to function properly. Apply a full bed of mortar over the metal plate to uniformly distribute the lintel load.
FM 5-428 Chptr 8 Concrete Masonry Figure 8-21. Installing precast concrete lintels without and with steel angles 8-30 .
Allow any droppings to dry and harden. also paint will not cover them. embedded mortar smears. Always patch mortar joints and fill holes made by nails or line pins with fresh mortar. Installing precast concrete sills PATCHING AND CLEANING BLOCK WALLS 8-32. When laying concrete masonry walls. or with a trowel. be very careful not to smear mortar into the block surfaces. You can then chip off most of the mortar with a small piece of broken concrete block (see Figure 8-23). because you cannot remove hardened. 8-31 . A final brushing of the spot will remove practically all of the mortar.FM 5-428 Chptr 8 Concrete Masonry Figure 8-22. even with an acid wash.
FM 5-428 Chptr 8 Concrete Masonry Figure 8-23. Cleaning mortar droppings from concrete block wall 8-32 .
The mason is responsible for laying out the job to do the work properly. 8-33 . but for strength and stability use mortar. Helpers aid the mason in laying out the job and sometimes lay out blocks ahead on an adjacent course to expedite the mason's work. but each layer must contain bonding stones that extend through the wall (as shown in Figure 8-25) to tie the walls together. and supplies concrete blocks and mortar to the mason as needed. keeps it tempered. Rubble stone masonry RANDON STONE MASONRY 8-36. SECTION III. There are two types of rubble-stone masonry: random and coursed. and installing anchor bolts and ties in intersecting walls. You can use rubble stone masonry (see Figure 8-24 below) for walls--both above and below ground--and for bridge abutments. This type is the crudest of all types of stonework. making joints. You can lay up rubble masonry with or without mortar. Figure 8-24. RUBBLE RUBBLE STONE MASONRY 8-35. particularly when form lumber or masonry units are not available.FM 5-428 Chptr 8 Concrete Masonry 8-33. Masons must make sure that the walls are plumb and that courses are level. Make the bed joints horizontal for stability. 8-34. the build or head joints can run in any direction. The mason's helper mixes mortar. It does not require laying the stone in courses (see Figure 8-24 above). They are also responsible for the quality of all the detail work such as cutting and fitting masonry units.
FM 5-428 Chptr 8 Concrete Masonry
Figure 8-25. Bonding stones extend through a rubble stone masonry wall COURSED RUBBLE MASONRY 8-37. This type contains roughly squared stones laid in nearly continuous horizontal bed joints as shown in Figure 8-24.
8-38. The two main random rubble masonry materials are stones and mortar. Some of the more common suitable stones are limestone, sandstone, granite, and slate. STONES 8-39. Use stones that are strong, durable, and cheap for random rubble masonry. Durability and strength depend on the stone's chemical composition and physical structure. Use unsquared stones or fieldstones from nearby ledges or quarries. No stones should be larger than what two persons can handle easily. The larger the variety of sizes you select, the less mortar you need. MORTAR 8-40. Table 7-1 gives the proportions of the portland-cement-lime mortar mixture to use with random rubble masonry. Mortar made with ordinary portland cement stains most types of stone. To prevent staining, substitute nonstaining white portland cement. Lime usually does not stain the stone.
8-41. The quality of workmanship affects the economy, durability, and strength of a rubble stone masonry wall more than any other factor. Lay out the wall-q By eye. If the wall does not have to be exactly plumb and true to line, lay it out by eye
FM 5-428 Chptr 8 Concrete Masonry
without using a level and line. This requires frequent sighting. By line. If the wall must be exactly plumb and true to line, erect wood corner posts to serve as corner leads, and lay the stone with a line. Remember that some parts of the stone will extend farther away from the line than other parts. Do not try to lay the stone in level courses.
RULES FOR LAYING 8-42. Lay each stone on its broadest face. If appearance is important, place the larger stones in the lower courses. Lay stones of increasingly smaller sizes as you build to the top of the wall. q Moistening. Moisten porous stones before placing them in mortar to prevent water absorption from the mortar, thereby weakening the bond. q Packing and filling. Pack adjoining stones as tightly as practicable, completely filling any spaces between them with smaller stones and mortar. q Removing. If removing a stone after placing it on the mortar bed, lift it clear and reset it. FOOTINGS 8-43. Because a footing is always larger than the wall itself, use the largest stones in the footing to give it greater strength and lessen the risk of unequal settlement. Select footing stones as long as the footing is wide, if possible. Lay them in a mortar bed about 2 inches deep, and fill all the spaces between them with smaller stones and mortar. BED JOINTS 8-44. Bed-joint thickness varies with the stone you use. Spread enough mortar on top of the lower course stone to completely fill the space between it and the stone you are placing. Take care not to spread mortar too far ahead of the stonelaying. HEAD JOINTS OR BUILDS 8-45. Form the head joints before the bed joint mortar sets up. After laying three or four stones, make the head joints by slushing the small spaces with mortar and filling the larger spaces with both small stones and mortar. BONDING STONES 8-46. Be sure to use one bonding stone for every 6 to 10 square feet of wall. Bonding stones pass all the way through the wall as shown in Figure 8-25. Offset each head joint from adjacent head joints above and below it as much as possible (see Figure 8-25) to bond the wall together and make it stronger.
FM 5-428 Chptr 8 Concrete Masonry
Figure 8-25. Bonding stones extend through a rubble stone masonry wall
FM 5-428 Chptr 9 Brick and Tile Masonry
Chapter 9
Brick and Tile Masonry
9-1. For at least 5000 years, bricks have been popular for their strength, durability, and beauty. Although traditionally made of natural clay that is heated in a kiln at high temperatures, many bricks today are made from compressed concrete and come in a wide variety of shapes and colors. Bricks can be used for a variety of structures including house walls, garden walls, retaining walls, chimneys and fireplaces, and also pavers for driveways, walkways, and patios. SECTION I. CHARACTERISTICS OF BRICK
9-2. Structural clay products includes brick, hollow tile of all types, and architectural terra cotta, but exclude thin wall tile, sewer pipe, flue linings, and drain tile. BRICK MASONRY UNITS 9-3. Bricks are small masonry units that are either solid or cored but not more than 25 percent. They are kiln-fired (baked) from various clay and shale mixtures. The chemical and physical characteristics of the ingredients change considerably and combine with the kiln temperature to produce the brick in a variety of colors and hardnesses. The clay or shale pits in some regions yield a product that is simply ground, moistened, formed, and baked into durable brick. In other regions, the clay or shale from several pits must be mixed to produce durable brick. Bricks are small enough to place with one hand. Uniform units can be laid in courses with mortar joints to form walls of almost unlimited length and height. BRICK SIZES AND WEIGHT 9-4. Standard United States (US) bricks are 2 1/4 by 3 3/4 by 8 inches actual size. They may have three core holes or ten core holes. Modular US bricks are (2 2/3 by 4 by 8 inches) nominal size, normally having three core holes. English bricks are 3 by 4 1/2 by 9 inches, Roman bricks are 1 1/2 by 4 by 12 inches, and Norman bricks are 2 3/4 by 4 by 12 inches nominal size. Actual brick dimensions are smaller, usually by an amount equal to mortar joint width. Brick weighs from 100 to 150 pounds per cubic foot, depending on its ingredients and firing duration. Well-burned brick is heavier than underburned brick. CUT SHAPES 9-5. Sometimes you must cut a brick into various shapes to fill in spaces at corners and other locations where a full brick does not fit. Figure 9-1 shows the more common cut shapes: half or
FM 5-428 Chptr 9 Brick and Tile Masonry
bat, three-quarter closure, quarter closure, king closure, queen closure, and split.
Figure 9-1. Common cut brick shapes SURFACE NAMES 9-6. The five surfaces of a brick are called face, side, cull, end, and beds as shown in Figure 9-2.
Figure 9-2. Names of brick surfaces BRICK CLASSIFICATION 9-7. The three general types of structural brick-masonry units are solid, hollow, and architectural terra cotta. All three can serve a structural function, a decorative function, or a combination of both. The three types differ in their formation and composition, and are specific in their use. Bricks commonly used in construction are-q Building bricks. Also called common, hard, or kiln-run bricks, these bricks are made from ordinary clays or shales and fired in kilns. They have no special scoring, markings, surface texture, or color. Building bricks are generally used as the backing courses in either solid or cavity brick walls because the harder and more durable kinds are preferred. q Face bricks. These are better quality and have better durability and appearance than
FM 5-428 Chptr 9 Brick and Tile Masonry
building bricks because they are used in exposed wall faces. The most common face brick colors are various shades of brown, red, gray, yellow, and white. Clinker bricks. These bricks are oven-burnt in the kiln. They are usually rough, hard, durable, and sometimes irregular in shape. Pressed bricks. These bricks are made by the dry-press process rather than by kiln-firing. They have regular smooth faces, sharp edges, and perfectly square corners. Ordinarily, they are used as face bricks. Glazed bricks. These have one surface coated with a white or other color of ceramic glazing. The glazing forms when mineral ingredients fuse together in a glass-like coating during burning. Glazed brick is particularly suited to walls or partitions in hospitals, dairies, laboratories, and other structures requiring sanitary conditions and easy cleaning. Fire bricks. These are made from a special type of fire clay to withstand the high temperatures of fireplaces, boilers, and similar constructions without cracking or decomposing. Fire brick is generally larger than other structural brick, and often is hand-molded. Cored bricks. These bricks have ten holes (two rows of five holes each) extending through their beds to reduce weight. Walls built from all cored bricks are not much different in strength than walls built from all solid bricks, and both have about the same resistance to moisture penetration. Whether cored or solid, use the more easily available brick that meets building requirements. European bricks. Their strength and durability (particularly English and Dutch bricks) are about the same as US clay bricks. Sand-lime bricks. These bricks are made from a lean mixture of slaked lime and fine sand containing a lot of silica. They are molded under mechanical pressure and hardened under steam pressure. These are used extensively in Germany.
9-8. The strength of a single brick masonry unit varies widely, depending on its ingredients and manufacturing method. The main factors governing the strength of brick masonry are-q Brick strength. q Mortar strength and elasticity. q Bricklayer workmanship. q Brick uniformity. q Bricklaying method used. RANGES 9-9. Bricks can have an ultimate compressive strength as low as 1,600 psi, whereas some well-burned bricks have compressive strengths exceeding 15,000 psi. PORTLAND-CEMENT-LIME MORTAR 9-10. Brick masonry laid with portland-cement-line mortar is stronger than an individual brick unit because this mortar is normally stronger than the brick. The load-carrying capacity of a wall or column made with plain lime mortar is much less than half that made with
if not corrected. use enough force to press the mortar tightly against the brick on both sides of the joint. Fire resistance of brick load-bearing walls laid with portland-cement-lime mortar Normal Wall Thickness. A field test to determine if the brick has absorptive qualities is as follows: Using a medicine dropper. because freeze-thaw action is almost the only type of weathering that affects it. If the brick absorbs all the water in less than 1 1/2 minutes. When tooling. will suck the water out of the mortar preventing complete hydration. A brick's resistance to weathering depends almost entirely upon its resistance to water penetration. DRY BRICK 9-11. Table 9-1. A brick wall made with superior workmanship will resist rain water penetration during a storm lasting as long as 24 hours accompanied by a 50 to 60 mile per hour wind. Table 9-1 gives the hours of fire resistance for various thicknesses of brick walls determined by tests conducted on brick walls laid with portland-cement-lime mortar. Fill the joints between the brick solidly. in Hours 4 Solid 8 Solid Clay or shale Clay or shale 1 1/4 5 Plaster on One Side. The compressive working strength of a brick wall or column laid with cement-lime mortar normally ranges from 500 to 600 psi. 9-14. especially in the face tier. FIRE RESISTANCE 9-15. Mortar joints that bond tightly to the brick resist moisture penetration better than joints with loose bonds. Incombustible Members Framed into Wall or not Framed in Members No Plaster.FM 5-428 Chptr 9 Brick and Tile Masonry portland-cement-lime mortar. Although good bricklaying workmanship does not permit water penetration. sufficient water must be present to completely hydrate the portland cement in the mortar. thoroughly wet the bricks and allow time for the surfaces to air-dry before placing. To correct this condition. WEATHER RESISTANCE 9-12. Two important factors in preventing water penetration are tooled-mortar joints and caulking around windows and door frames. place 20 drops of water in a 1-inch circle (about the size of a quarter). then it will suck the water out of the mortar when laid. in Inches Types of Wall Material Ultimate Fire-Resistance Period. 9-13. it provides some means of removing moisture that does penetrate the masonry. In order for mortar to bond to brick. such as properly designed flashing or the use of cavity walls. Tool the joint to a concave surface before the mortar sets up. Bricks sometimes have high absorption and. in Hours 1 3/4 6 Plaster on Two SIdes. in Hours 2 1/2 7 9-4 . The ASTM standard method for conducting fire tests was used. Slushing or grouting the joints after laying the brick does not fill the joint completely.
the heavier the wall. because the wall itself takes up a lot of the expansion and contraction. travel a long way along the wall. impact sounds. A brick's resistance to abrasion depends largely upon its compressive strength. Brick walls are massive and provide good sound insulation. Generally. Brick walls poorly absorb sound originating within the walls and reflect much of the sound back into the structure. SECTION II. HEAT 9-18. Solid-brick masonry walls provide very little insulation from heat and cold. increases its resistance to sound transmission from one side of the wall to the other. the better its sound-insulating value. Dividing a wall into two or more layers. However. BRICKLAYING METHODS 9-5 .FM 5-428 Chptr 9 Brick and Tile Masonry 12 Solid 8 Hollow rowlock 12 Hollow rowlock 9 to 10 Cavity 4 Solid 8 Solid 12 Solid Clay or shale Clay or shale Clay or shale Clay or shale Sand lime Sand lime Sand lime 10 2 1/2 5 5 1 3/4 7 10 10 3 6 6 2 1/2 8 10 12 4 7 7 3 9 12 NOTE: Not less than 1/2 inch of 1-3 sanded gypsum plaster is required to develop these rating. A cavity wall or a brick wall backed with hollow clay tile gives much better insulating value. such as a cavity wall. but longer walls require one expansion joint for every 200 feet. A brick masonry wall expands and contracts with temperature change. Therefore. INSULATING QUALITIES OF BRICK MASONRY 9-17. SOUND 9-19. the amount of movement calculated theoretically does not actually occur. which is determined by how well it was fired. walls up to 200 feet long do not need expansion joints. However. Well-burned brick has excellent wearing qualities. the sound insulation provided by a wall more than 12 inches thick is not much greater than a wall 10 to 12 inches thick. ABRASION RESISTANCE 9-16. However. such as a hammer striking the wall.
Wythe. thereby achieving maximum efficiency. 9-6 . A brick laid on its end with its face perpendicular to the face of the wall. Bull stretcher. Plan the scaffolding before the work begins. A rowlock brick laid with its bed perpendicular to the face of the wall. Header. those used in bricklaying. which are generally the same as. Paragraphs 7-3 and 7-4 describe mason's tools and equipment. one masonry unit thick. Organize your work to ensure a continual supply of brick and mortar. Sometimes called a tier. Rowlock. After learning the fundamentals. A masonry unit laid flat on its bed along the length of a wall with its face parallel to the face of the wall. You need to know the specific terms that describe the position of masonry units and mortar joints in a wall (see Figure 9-3). or similar to. Good bricklaying procedures depend on good workmanship and efficiency. such as the thickness of masonry separating flues in a chimney. Each motion should have a purpose and accomplish a particular result. BRICK MASONRY TERMS 9-21. and build it so that it interferes as little as possible with other workers. Soldier. Stretcher. Bull header. horizontal layers (or rows) of masonry units bonded together. A rowlock brick laid with its bed parallel to the face of the wall. Each continuous. A header laid on its face or edge across the width of a wall. These terms include-q q q q q q q q Course. study your own work to eliminate unnecessary motions.FM 5-428 Chptr 9 Brick and Tile Masonry FUNDAMENTALS 9-20. A masonry unit laid flat on its bed across the width of a wall with its face perpendicular to the face of the wall. Efficiency means to do the work with the fewest possible motions. One of several continuous. Generally used to bond two wythes. vertical section of a wall.
FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-3. This means how the individual masonry units interlock or tie together into a single structural unit. mortar bond.Embedding metal ties in connecting joints. This is adhesion of the mortar joint to the masonry units or to the reinforcing steel.Using grout to adhere adjacent wythes of masonry. . Mortar bond.Overlapping (interlocking) the masonry units. Masonry units and mortar joints TYPES OF BONDS 9-22. or pattern bond. You can achieve structural bonding of brick and tile walls in one of three ways: . . The term bond as used in masonry has three different meanings: structural bond. q Structural bond. Metal ties are also used as bonds. q 9-7 .
The joints between stretchers in all stretcher courses do not align vertically. -Running bond. or seventh course. You can vary the pattern with combinations and modifications of the basic patterns shown in Figure 9-4. When headers are not required for structural bonding. Metal ties. sixth. or 8-inch-thick stretcher units when available. . In laying out any bond pattern. The headers in every other course center over and under the stretchers in the courses in between. The running bond is used largely in cavity wall construction. A variation of the English bond.English bond.Common or American bond. English bond. This is purely a pattern bond. Use blind headers in courses that are not structural bonding courses. the English cross or Dutch bond differs only in that the joints between the stretchers in the stretcher courses align vertically. The headers center over and under the stretchers. stack bond. brick veneer walls. a 2-inch or quarter closure starts the course. common or American bond. The pattern may result from the structural bond or may be purely decorative and unrelated to the structural bond. use bricks called blind headers. The joints between stretchers in all stretcher courses align vertically.Flemish bond. and facing tile walls made with extra wide stretcher tile. therefore metal ties usually form the structural bond. and English cross or Dutch bond. use a three-quarter closure at the corner of each header course. consisting of all stretchers. . .English cross or Dutch bond. . In large wall areas or for load-bearing construction.FM 5-428 Chptr 9 Brick and Tile Masonry q Pattern Bond. Start the corners two different ways. These joints center on the headers in the courses above and below. insert steel-pencil rods into the horizontal mortar joints as reinforcement. This is pattern formed by the masonry units and mortar joints on the face of a wall. You must use dimensional-accurate or prematched units to achieve good vertical joint alignment. with no overlapping units and all vertical joints aligning. . This is variation of the running bond having a course of full-length headers at regular intervals that provide the structural bond as well as patterns.Stack bond. This pattern usually bonds to the backing with rigid steel ties. This pattern consists of alternating courses of headers and stretchers. Figure 9-5 shows three typical metal ties. In a common bond. The bond has no headers. in the Dutch corner. When a wall bond has no header courses. This is the simplest of the six bonds. Flemish bond. use metal ties to bond the exterior wall brick to the backing courses. Figure 9-4 shows the six basic bond patterns in common use today: running bond. and with the English corner. q 9-8 . Header courses usually appear at every fifth. be sure to start the corners correctly. a three-quarter closure starts each course. depending on the structural bonding requirements or the common bond that will vary with a Flemish header course. Each course consists of alternating headers and stretchers.
9-9 . and frequently at floor lines. This type of concealed flashing with tooled mortar joints often retains water in the wall for long periods and. This also includes roof and parapet or a roof and chimney. by concentrating the moisture at one spot it does more harm than good. Install flashing at any spot where moisture is likely to enter a brick masonry structure. Metal ties FLASHING 9-23. Weep holes are even more important when appearance requires the flashing to stop behind the wall face instead of extending through the wall. above openings such as doors and windows.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-4. Types of masonry bond Figure 9-5. Provide weep holes at intervals of 18 to 24 inches to drain water that accumulates on the flashing to the outside. Flashing diverts the moisture back outside. Always install flashing under horizontal masonry surfaces such as sills and copings and at intersections between masonry walls and horizontal surfaces. depending on the type of construction. The flashing should extend through the exterior wall face and then turn downward against the wall face to form a drop.
You can pick up enough mortar to spread one to five bricks depending on the wall space and your skills. Correct way to hold a trowel 9-10 . If you are right-handed. not encircling it. Figure 9-6. a pickup for five bricks is a full load for a large trowel as shown in view 2 of Figure 9-7. Irregularly shaped bricks may require mortar joints up to 1/2 inch thick to compensate for the irregularities. However. Pointing is filling exposed joints with mortar immediately after laying a wall. A pickup for one brick forms only a small pile along the left edge of the trowel. You cannot make solid joints this way. pick up mortar from the outside of the mortar-board pile with the left edge of your trowel (see Figure 9-7 below). Figure 9-6 shows the correct way to hold a trowel firmly in the grip with your thumb resting on top of the handle. however.FM 5-428 Chptr 9 Brick and Tile Masonry MAKING AND POINTING MORTAR JOINTS 9-24. Even if you fill the space between the bricks completely. A slush joint is made simply by depositing the mortar on top of the head joints allowing it to run down between the bricks to form a joint. and a poor bond will result. PICKING UP AND SPREADING MORTAR 9-27. 9-26. MORTAR JOINT 9-25. Use this thickness whenever the bricks are regular enough in shape to permit it. mortar joints 1/4 inch thick are the strongest. There is no rule governing the thickness of a brick masonry mortar joint. You can also fill holes and correct defective mortar joints by pointing. there is no way you can compact the mortar against the brick faces. using a pointing trowel.
spreading the mortar working from left to right along the wall. MAKING BED AND HEAD JOINT 9-29. Do not spread the mortar for a bed joint too far ahead of laying (the length of 4 or 5 bricks is best). Holding the left edge of the trowel directly over the centerline of the previous course. Mortar spread out too far ahead dries out before the bricks bedded in it and causes a poor bond as shown in Figure 9-8. Return any leftover mortar to the trowel mortarboard. Picking up and spreading mortar 9-28. tilt the trowel slightly and move it to the right (see view 3 Figure 9-7) dropping an equal amount of mortar on each brick until the course is completed or the trowel is empty. If you are right-handed. The mortar must be soft and plastic so that the brick beds in it easily. A furrow that is too deep leaves a gap between the mortar and the bedded brick.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-7. Spread the mortar about 1 inch thick. 9-11 . which will reduce the wall's resistance to water penetration. and then make a shallow furrow in it (see Figure 9-9 below).
A poorly bonded brick Figure 9-9. 9-31. Cut off any mortar projecting beyond the wall line with the edge of the trowel (see Figure 9-9 above). Retain enough mortar on the trowel to butter the left end of the first brick you will lay in the fresh mortar and throw the rest back on the mortar board. Making a bed joint in a stretcher course 9-30. Make sure that the mortar completely fills the head joint.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-8. Apply as much mortar as will stick to the end of the brick and then push it into place. After bedding the 9-12 . Placing your thumb on one side of the brick and your fingers on the other. pick up the first brick to be laid (see Figure 9-10). even stroke. Use a smooth. squeezing out excess mortar at the head joint and at the sides as shown in Figure 9-11 below.
First. Figure 9-10. Making a head joint in a stretcher course INSERTING A BRICK IN A WALL 9-32. Proper way to hold a brick when buttering the end Figure 9-11. 9-13 .FM 5-428 Chptr 9 Brick and Tile Masonry brick. and then shove the brick into it (see view 2 of Figure 9-12) until mortar squeezes out of the four joints (see view 3 of Figure 9-12). cut off the excess mortar and use it to start the next end joint. In doing so you are assured that the joints are full of mortar at every point. Figure 9-12 shows how to insert a brick in a space left in a wall. Throw any surplus mortar on the back of the mortar board for retampering if necessary. spread a thick bed of mortar (see Figure 9-12).
Next shove the brick into place. Making a cross joint in a header course 9-34.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-12. Inserting a brick in a wall MAKING CROSS JOINTS AND JOINTS CLOSURE 9-33. Spread about 1 inch of 9-14 . Figure 9-13. Then spread mortar over the face of the header brick before placing it in the wall (see view 1 of Figure 9-13). squeezing out mortar at the top of the joint. Finally cut off the excess mortar as shown in view 2 of Figure 9-13. Spread the bed-joint mortar several brick widths in advance. Figure 9-14 shows how to lay a closure brick in a header course.
FM 5-428 Chptr 9 Brick and Tile Masonry mortar on the sides of the brick already in place (see view 1 of Figure 9-14). Figure 9-14. If you do disturb any adjacent bricks. as well as both ends of the closure brick (see view 2 of Figure 9-15). you must remove and relay them. Otherwise. allowing moisture to penetrate the wall. Making a closure joint in a header couse 9-35. as well as on both sides of the closure brick (see view 2 of Figure 9-14). Then lay the closure brick carefully into position. Then carefully lay the closure brick without disturbing the brick already in place (see view 3 of Figure 9-15). first spread plenty of mortar on the ends of the brick already in place (see view 1 of Figure 9-15). cracks will form between the brick and mortar. To make a closure joint in stretcher courses. without disturbing the brick already laid (see view 3 of Figure 9-14). 9-15 .
Hitting a sharp blow to one side of the cutting line should split the brick at the cutting line (see view 1 of Figure 9-17). first cut it roughly using the brick hammer head. q Using a bolster or brick set. When you must cut a brick to exact line. 9-16 . First cut a line around the brick using light blows. Making a closure joint in a stretcher course CUTTING BRICK 9-36. Hold the brick firmly while cutting it. and the bricklayer. using a brick hammer. q Using a brick hammer. Trim rough spots using the hammer blade as shown in view 2 of Figure 9-17. use a bolster (see Figure 9-16) or brick set. The straight side of the tool's cutting edge should face both the part of the brick to be saved. Use a brick hammer for normal cutting work.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-15. but leave enough brick to cut accurately with the brick set. One mason's hammer blow should break the brick. Bricks will either be cut with a bolster or a brick set. For an extremely hard brick. such as making the closure bricks and bats around wall openings or completing corners.
q Weather joint. Always finish a mortar joint before the mortar hardens too much. It sheds water from a wall surface more easily. q Concave joint. Purpose. shallow cracks develop immediately between the brick and the mortar. If joints are simply cut flush with the brick and not finished. Use force against the tool to press the mortar tight against the brick on both sides of the mortar joint. To make it. It is very weather tight. Figure 9-18 shows several types of joint finishes. Cutting brick with a bolster Figure 9-17. the more important of which are discussed below. Chapter 7. 9-17 . simply push downward on the mortar with the top edge of the trowel. make this joint using a jointer that is slightly larger than the joint. 9-37. Cutting a brick with a hammer FINISHING JOINTS. Finishing or tooling the joint using the jointer shown in Figure 7-1 . It is made by holding the trowel almost parallel to the face of the wall while drawing its point along the joint. q Flush joint. prevents such cracks. After removing the excess mortar with a trowel. The exterior surfaces of mortar joints are finished to make brick masonry more waterproof and give it a better appearance.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-16.
cement requires suf-ficient moisture to complete the hydration process. BRICKTENDER'S DUTIES 9-39. mortar. The bricktender fills the mortar board and places it in a convenient spot for the bricklayer. A footing must rest below the frost line to prevent foundation heaving and settlement. the bricklayer must make sure that the walls are plumb and the courses are level. q Dry brick absorbs water from the mortar rapidly. There are four reasons why bricks must be wet just before laying them: q A better bond is created between the brick and the mortar.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-18. and supplies material to the bricklayer. A qualified engineer must determine actual footing width and thickness for high walls and walls that will carry a heavy load. q Mortar spreads more evenly under a wet brick surface. The bricktender mixes mortar and carries brick. The bricklayer actually lays the brick and is responsible for laying out the job so that the finished masonry has the proper quality and appearance. BRICK CONSTRUCTION BRICKLAYER'S DUTIES 9-38. the cement will not harden properly. Therefore. LAYING FOOTINGS 9-40. A wall requires a footing when the supporting soil cannot withstand the wall load without a 9-18 . He assists in layout and rapid backup bricklaying by laying out bricks in a line on an adjacent course so that the bricklayer only has to move each brick a few inches to lay them. He also wets brick during warm weather. In wall construction. WALL FOOTINGS 9-41. particularly portland-cement mortar. To harden properly. if the brick absorbs too much water from the mortar. Joint finishes SECTION III. q Dust and dirt are washed from the brick surfaces because mortar adheres better to a clean brick. as needed.
The footing must be wider than the wall thickness as shown in Figure 9-19.story building having an 8-inch-thick wall. place a mortar bed about 1 inch thick on the subgrade to compensate for all irregularities. Figure 9-20 shows a footing for a 12 by 16-inch brick column. footings are normally made from concrete leveled on top to receive the brick or stone foundation walls. This footing requires the same construction method as the wall footing. Figure 9-19. For an ordinary one. Lay the first course of the foundation on the mortar bed followed by succeeding courses (see Figure 9-19). Although brick masonry footings are satisfactory.FM 5-428 Chptr 9 Brick and Tile Masonry further means of load redistribution. After preparing the subgrade. Laying a wall footing COLUMN FOOTINGS 9-42. 9-19 . a footing 16 inches wide and approximately 8 inches thick is usually large enough.
3/8 inch joint Course 1 Height 0' 2 5/8" Course 21 Height 4' 7 1/8" Course 41 Height 8' 11 5/8" Course 61 Height 13' 4 1/8" Course 81 Height 17' 8 5/8" 9-20 . Column footing LAYING AN 8-INCH COMMON-BOND BRICK WALL 9-43. 9-3. To build a wall of a given length.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-20. Space them equally. The solid 8. You can build both solid and hollow walls from brick masonry. LAYING OUT THE WALL 9-44. adjust the width of the head joints so that a particular number of bricks or a particular number plus a half-brick will equal the given length. Lay out the bricks for the foundation without mortar first.and 12-inch walls in common bond are the most familiar ones in the US. To do this use the following steps: Step 1. Table 9-2. as shown in Figure 9-21. The distance between them will equal the thickness of the head joints. Tables 9-2. Determining number of bricks in one course and head-joint widths Step 2. and 9-4 below give the number of courses in a wall of a given height using standard brick and different joint widths. Figure 9-21. Height of course using 2 1/4-inch brick.
FM 5-428 Chptr 9 Brick and Tile Masonry 2 3 0' 5 1/4" 0' 7 7/8" 22 23 24 25 26 4' 9 3/4" 5' 0 3/8" 5' 3" 5' 5 5/8" 5' 8 1/4" 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 9' 2 1/4" 9' 4 7/8" 9' 7 1/2" 9' 10 1/8" 10' 0 3/4" 10' 3 3/8" 10' 6" 10' 8 5/8" 10' 11 1/4" 11' 1 7/8" 11' 4 1/2" 11' 7 1/8" 11' 9 3/4" 12' 0 3/8" 12' 3" 12' 5 5/8" 12' 8 1/4" 12' 10 7/8" 13' 1 1/2" 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 13' 6 3/4" 13' 9 3/4" 14' 0" 14' 2 5/8" 14' 5 1/4" 14' 7 7/8" 14' 10 1/2" 15' 1 1/8" 15' 3 3/4" 15' 6 3/8" 15' 9" 15' 11 5/8" 16' 2 1/4" 16' 4 7/8" 16' 7 1/2" 16' 7 1/2" 17' 0 3/4" 17' 3 3/8" 17' 6" 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 17' 11 1/4" 18' 1 7/8" 18' 4 1/2" 18' 7 1/8" 18' 9 3/4" 19' 0 3/8" 19' 3" 19' 5 5/8" 19' 8 1/4" 19' 10 7/8" 20' 1 1/2" 20' 4 1/8" 20' 6 3/4" 20' 9 3/8" 21' 0" 21' 2 5/8" 21' 5 1/4" 21' 7 7/8" 21' 10 1/2" 4 0' 10 1/2" 5 6 7 8 1' 1 1/8" 1' 3 3/4" 1' 6 3/8" 1' 9" 27 5' 10 7/8" 28 29 30 31 32 33 34 35 6' 1 1/2" 6' 4 1/8" 6' 6 3/4" 6' 9 3/8" 7' 0" 7' 2 5/8" 7' 5 1/4" 7' 7 7/8" 9 1' 11 5/8" 10 11 12 2' 2 1/4" 2' 4 7/8" 2' 7 1/2" 13 2' 10 1/8" 14 15 16 17 3' 0 3/4" 3' 3 3/8" 3' 6" 3' 8 5/8" 36 7' 10 1/2" 37 38 39 40 8' 1 1/8" 8' 3 3/4" 8' 6 3/8" 8' 9" 18 3' 11 1/4" 19 20 4' 1 7/8" 4' 4 1/2" Table 9-3. 1/2-inch joint Course 1 Height 0' 2 3/4" Course 21 Height 4' 9 3/4" Course 41 Height 9' 4 3/4" Course 61 Height 13' 11 3/4" Course 81 Height 18' 6 3/4" 9-21 . Height of course using 2 1/4-inch brick.
FM 5-428 Chptr 9 Brick and Tile Masonry 2 3 4 5 6 7 8 9 10 11 12 0' 5 1/2" 0' 8' 1/4" 0' 11" 1' 1 1/4" 1' 4 1/2" 1' 7 1/4" 1' 10" 2' 0 3/4" 2' 3 1/2" 2' 6 1/4" 2' 9" 22 23 24 25 5' 0 1/2" 5' 3 1/4" 5' 6" 5' 8 3/4" 42 9' 7 1/2" 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 14' 2 1/2" 14' 5 1/4" 14' 8" 14' 10 3/4" 15' 1 1/2" 15' 4 1/4" 15' 7" 15' 9 3/4" 16' 0 1/2" 16' 3 1/4" 16' 6" 16' 8 3/4" 16' 11 1/2" 17' 2 1/4" 17' 5" 17' 7 3/4" 17' 10 1/2" 18' 1 1/4" 18' 4" 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 18' 9 1/2" 19' 0 1/4" 19' 3" 19' 5 3/4" 19' 8 1/2" 19' 11 1/4" 20' 2" 20' 4 3/4" 20' 7 1/2" 20' 10 1/4" 21' 1" 21' 3 3/4" 21' 6 1/2" 21' 9 1/4" 22' 0" 22' 2 3/4" 22' 5 1/2" 22' 8 1/4" 22' 11" 43 9' 10 1/4" 44 10' 1" 45 10' 3 3/4" 46 10' 6 1/2" 47 10' 9 1/4" 48 11' 0" 26 5' 11 1/2" 27 28 29 6' 2 1/4" 6' 5" 6' 7 3/4" 49 11' 2 3/4" 50 11' 5 1/2" 51 11' 8 1/4" 52 11' 11" 30 6' 10 1/2" 31 32 33 34 35 36 37 38 7' 1 1/4" 7' 4" 7' 6 3/4" 7' 9 1/2" 8' 0 1/4" 8' 3" 8' 5 3/4" 8' 8 1/2" 13 2' 11 3/4" 14 15 16 3' 2 1/2" 3' 5 1/4" 3' 8" 53 12' 1 3/4" 54 12' 4 1/2" 55 12' 7 1/4" 56 12' 10" 17 3' 10 3/4" 18 19 20 4' 1 1/2" 4' 4 1/4" 4' 7" 57 13' 0 3/4" 58 13' 3 1/2" 59 13' 6 1/4" 60 13' 9" 39 8' 11 1/4" 40 9' 2" Table 9-4. 5/8-inch joint Course 1 2 Height 0' 2 7/8" 0' 5 3/4" Course 21 22 Height 5' 0 3/8" 5' 3 1/4" Course 41 42 Height 9' 9 7/8" 10' 0 3/4" Course 61 62 Height 14' 7 3/8" 14' 10 1/4" Course 81 82 Height 19' 4 7/8" 19' 7 3/4" 9-22 . Height of course using 2 1/4-inch brick.
The following steps should be used in laying the corner leads: Step 1. Erect the wall corners first. This is called laying the leads.FM 5-428 Chptr 9 Brick and Tile Masonry 3 0' 8 5/8" 23 24 5 ' 6 1/8" 5' 9" 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 10' 3 5/8" 10' 6 1/2" 10' 9 3/8" 11' 0 1/4" 11' 3 1/8" 11' 6" 11' 8 7/8" 11' 11 3/4" 12' 2 5/8" 12' 5 1/2" 12' 8 3/8" 12' 11 1/4" 13' 2 1/8" 13' 5" 13' 7 1/8" 13' 10 3/4" 14' 1 5/8" 14' 4 1/2" 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 15' 1 1/8" 15' 4" 15' 6 7/8" 15' 9 3/4" 16' 0 5/8" 16' 3 1/2" 16' 6 3/8" 16' 9 1/4" 17' 0 1/8" 17' 3" 17' 5 7/8" 17' 8 3/4" 17' 11 5/8" 18' 2 1/2" 18' 5 3/8" 18' 8 1/4" 18' 11 1/8" 19' 2" 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 19' 10 5/8" 20' 1 1/2" 20' 4 3/8" 20' 7 1/4" 20' 10 1/8" 21' 1" 21' 3 7/8" 21' 6 3/4" 21' 9 5/8" 22' 0 1/2" 22' 3 3/8" 22' 6 1/4" 22' 9 1/8" 23' 0" 23' 2 7/8" 23' 5 3/4" 23' 8 5/8" 23' 11 1/2" 4 0' 11 1/2" 5 6 7 8 9 10 11 1' 2 3/8" 1' 5 1/4" 1' 8 1/8" 1' 11" 2' 1 7/8" 2' 4 3/4" 2' 7 5/8" 25 5' 11 7/8" 26 27 28 6' 2 3/4" 6' 5 5/8" 6' 8 1/2" 29 6' 11 3/8" 30 31 32 7' 2 1/4" 7' 5 1/8" 7' 8" 12 2' 10 1/2" 13 14 15 16 17 18 19 20 3' 1 3/8" 3' 4 1/4" 3' 7 1/8" 3' 10" 4' 0 7/8" 4' 3 3/4" 4' 6 5/8" 4' 9 1/2" 33 7' 10 7/8" 34 35 36 8' 1 3/4" 8' 4 5/8" 8' 7 1/2" 37 8' 10 3/8" 38 39 40 9' 1 1/4" 9' 4 1/8" 9' 7" LAYING CORNER LEADS 9-45. 9-23 .
9-24 . Step 3. Step 4. Step 1 of Figure 9-22 below shows how to start laying a corner lead. Build the corner leads up about six or seven courses. Header course 9-46.FM 5-428 Chptr 9 Brick and Tile Masonry Step 2. or to the height of the next header course. the first course is a header course. Use the leads as a guide when laying the rest of the wall. Normally. Lay the face tier.
The exterior edges of both closures must be flush with the exterior face of the foundation. Remove all excess mortar and check the tops of the quarter closures to make sure that they are flush with bricks a and b. o. cut the quarter closures e and f. and k the same way. for laying closure bricks.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-22. and lay them as described in paragraph 9-34. shove it into position as shown. 9-25 . Laying first course of corner lead for 8-inch common-bond brick wall Step 1. Step 12. Step 7. Lay bricks h. m. Step 10. Step 6. Step 9. Check their levels by placing the mason's level in the positions shown in step 4 of Figure 9-22. You must lay 12 header bricks in the first course of the corner lead--six bricks on each side of the three-quarter closures a and b. Spread mortar on brick g (see step 4 of Figure 9-22). Cut off the mortar that squeezes out of the joints. The end of this brick must also be flush with the exterior face of the foundation. Lay a 1-inch mortar bed on the foundation. n. Lay bricks l. and p in the same manner (see step 5 of Figure 9-22). Step 8. All brick ends must be flush with the foundation surface. and check the levels of the two three-quarter closures. Spread mortar on the end of the second three-quarter closure and form a 1-inch thick head joint as described in paragraph 9-29 (see b in step 2 of Figure 9-22). Step 3. Cut two three-quarter closures and press one into the mortar bed until it makes a bed joint 1/2 inch thick (see a in step 2 of Figure 9-22. i. Check its level using the mason's level in the positions shown in step 3 of Figure 9-22. After laying this brick in the proper position. Step 4. j. and remove any excess mortar. Step 5. Step 11. Spread mortar on one bed of a whole brick (see c in step 3 of Figure 9-22) and lay it as shown. Step 2. Lay a mason's level in the two positions shown in step 2 of Figure 9-22. Stretcher course 9-47. Lay the second course of the corner lead (a stretcher course) as shown in steps 1 and 2 of Figure 9-23 below.
9-26 . Step 4. f. Spread a 1-inch mortar bed over the first course and make a shallow furrow in it. Push brick (a) (see step 2 of Figure 9-23) into the mortar bed until it makes a joint 1/2 inch thick. e. Plumb the corners in several places by placing the mason's level in the vertical position as shown in Figure 9-24 below. Remove the excess mortar and check the joints for thickness. Step 3. Step 5. Check them by placing the mason's level in the position shown in step 2 of Figure 9-23 to make sure they are level. d. Spread mortar on the end of the brick and shove it into place. As step 3 of Figure 9-23 shows. Lay bricks c. the second course requires seven bricks.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-23. Step 2. and g the same way. Laying second course of corner lead for 8-inch common-bond brick wall Step 1.
Check the level of the lead courses continuously. Plumbing a corner Step 6. 9-27 . Build the opposite corner lead the same way. the top of the second course in one corner lead must be the same height above the foundation as the second course in the opposite corner. Lay the portion of the wall between the leads using the leads as a guide. Make sure that the tops of corresponding courses are the same level in each lead. If the masonry is not plumb. It is not good practice to move brick after it is laid in the mortar. Step 2. and then use it to check the course height in the corner leads as you build them. Opposite Corner Leads 9-49. move the bricks either in or out until the lead is exactly plumb. Step 1. Mark a long 2-by 2-inch pole with the correct course heights above the foundation. Be sure to finish or tool the joints before the mortar sets. Step 3. Use a line. Lay the remaining bricks in the corner lead as you did the bricks in the second course.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-24. LAYING THE FACE TIER BETWEEN THE CORNER LEADS 9-50. Plumb the lead after laying the first few courses. as shown in Figure 9-25 to lay the face tier of brick for the wall between the leads. Leveling 9-48. For example. Take great care to place the bricks accurately the first time.
The line pin prevents the taut line from unwinding. LAYING THE BACKUP TIER BETWEEN THE CORNER LEADS 9-51. Step 5. and attach it to the nail in the right-hand lead. Step 4. but check it occasionally at several points.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-25. For an 8-inch wall. when the line is in place. Lay the stretcher course as described in paragraph 9-47. Move the line to the top of the next mortar joint for the second or stretcher course. Step 6. If the corner leads are built accurately. level with the top of the brick. Lay the backup brick for the corner leads first. Then lay the backup tier. but not including. Drive nails into the top of the cross joints. You need not use a mason's level continually when laying the wall between the leads. and finish the face joints before the mortar hardens. the second header course (normally five stretcher courses). It is better to use a tool called a line pin that resembles a triangular-shaped nail to attach the line at the right-hand or pull end. Lay the first or header course in between the two corner leads as described in paragraph 9-46. Push the brick into position with its top edge 1/16 inch behind the line. Lay the face tier of the wall between the leads up to. Attach the line to the nail in the left-hand lead. 9-28 . Position the line 1/16 inch outside the wall face. lay the second header course in the face tier. After laying the backup tier up to the height of the second header course. Be sure not to crowd the line. followed by the remaining brick. Using a line to lay face tier of brick between corner lead Step 1. Step 3. the entire wall will be level and plumb. you do not need to use a line for the backup brick as you do in a 12-inch wall. pull it taut. Step 7. as shown in Figure 9-26. Step 2.
Note that the construction is similar to that of an 8-inch wall. Then construct the wall between the leads as described above. continue laying the corner leads up six more courses. 9-29 . except that it includes a second tier of backup brick (see view 3 of Figure 9-27). When the wall for the entire building is laid up to a height that includes the second header course. Laying backup brick for the corner lead of an 8-inch common bond brick wall 9-52. LAYING A 12-INCH COMMON-BOND BRICK WALL 9-53.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-26. Figure 9-27 below shows how to lay the first three courses of a 12-inch common bond-brick wall. Repeat the entire procedure until the wall is laid to the required height.
using a line for the inside tier. Lay two overlapping header courses first (see view 1 of Figure 9-27). and build the corner leads.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-27. Step 2. 9-30 . Laying a 12-inch common-bond brick wall Step 1. Lay the two tiers of backing brick.
WINDOW OPENINGS 9-57. Procedures to use when constructing window openings are as follows: 9-31 . When building a long wall. Figure 9-28. Now use a trig to keep the line from sagging or being windblown toward or away from the wall face. Each night cover the tops of all work completed inside the brick walls to protect them from weather damage. A piece of broken brick rests on top of the trig to hold it in position. You must plan ahead when laying any wall containing windows. Use a trig to support the line when building a long wall CONSTRUCTING WINDOW AND DOOR OPENINGS 9-56. PROTECTING WORK INSIDE WALLS 9-54. Use the boards or tarpaulins secured by loose bricks.FM 5-428 Chptr 9 Brick and Tile Masonry Step 3. USING A TRIG 9-55. Then stretch a line from the left-hand lead to the middle lead to the right-hand lead. Lay the second course as shown in view 2 of Figure 9-27. A trig (see Figure 9-28) is a second short piece of line that loops around the main line and fastens to the top edge of a previously laid brick in the middle lead. erect a third lead between the corner leads. making sure to leave openings of the correct size as the bricklaying proceeds. and the third course as shown in view 3 of Figure 9-27.
If the mark for the top of the last course does not come out to the proper level. lay the rowlock sill course as shown in Figure 9-29 below. Finish the exterior joint surfaces carefully to make them watertight. Laying the brick. Laying the rowlock sill course.FM 5-428 Chptr 9 Brick and Tile Masonry q q q q q Planning. Lay the corner leads with joints of the calculated thickness. you can lay the face tier brick with a minimum of cutting. and 4 feet 4 1/4 inches divided by 2 3/4 inches equals 19 courses. place the window frame on the rowlock sill course. Use the same procedure to construct a door opening (see Figure 9-30) as for a window 9-32 . if the sill is 4 feet 4 1/4 inches above the foundation using 1/2-inch mortar joints. When the corner leads are built. Calculate it this way: each brick plus one mortar joint equals 2 1/4 plus 1/2 equals 2 3/4 in per course. Marking. calculate how many courses will bring the wall up to that height. Now lay the rest of the wall around the frame until the top of the last course is not more than 1/4 inch above the window frame Figure 9-29. bracing it firmly until the masonry reaches about ingathered of the way up the frame. As soon as the mortar sets. The rowlock normally takes up a vertical space equal to two courses of brick. you must lay 19 courses before you reach the bottom of the sill. Constructing a window opening DOOR OPENING 9-58. The height of the wall to the top of a full course must equal that distance. (But do not remove the braces for several days so that the wall above the window frame sets properly). If the window openings are planned properly. Pitch the course downward away from the window. For example. find out the specified distance from the foundation to the bottom of the window sill. install a line as described earlier and stretch it across the bottom of the window openings. First. Lay the brick for the wall between the leads up to sill height using the calculated joint thickness. Lay the corner leads and the wall in between them so that the top of the last course is not more than 1/4 inch above the top of the window frame. Placing the frame. change the joint thickness you plan to use until it does. Use a pencil to mark the top of each course on the window frame itself. When the wall reaches sill height. Now.
or wood. To anchor the door frame to the masonry using screws or nails. Table 9-5 gives size and quantities of double-angle steel and wood lintels to use for various opening widths in both 8. cut pieces of wood to the size of a half closure and lay them in mortar the same as brick. CONSTRUCTION 9-60. properly installed steel reinforcing bars support the brick above wall openings. Figure 9-30. Close any space between the window or door frame and the lintel with blocking. Figures 9-31 and 9-32 below show how to place different kinds of lintels in different wall thickness.FM 5-428 Chptr 9 Brick and Tile Masonry opening. The placement and relative positioning of lintels are determined by both the wall thickness and the type of window or door specified. precast reinforced-concrete beams. If the lintel size is not specified.and 12-inch walls. It rests on top of the last brick course that is almost level with the top of the window or door frame. Figure 9-31 shows 9-33 . This information is usually on the building drawings. and its sides bed firmly in mortar. Then continue the wall above the window or door when the lintel is in place. The lintel above a window or door carries the weight of the wall above it. In reinforced brick masonry. INSTALLATION 9-61. Lintels are made from steel. and weather-strip it with bituminous materials. Place the wood blocks at several points along the top and sides of the door opening. Constructing a door opening LINTELS 9-59. Do not use wood lintels if possible.
Installing a double-angle steel lintel in an 8-inch wall 9-34 . Steel Angles* 2-3 1/2 x 3 1/2 x 1/4 3-4 x 4 x 4 1/4 4 Feet. Steel Angles* * Wood lintels should not be used for spans over 3 feet since they will burn out in case of fire and allow the bricks to fall. Steel Angles* 5 Feet. Table 9-5. Figure 9-31. Steel Angles* 6 Feet. Steel Angles* 2-3 1/2 x 3 1/2 x 1/4 3-4 x 4 x 1/4 2-3 1/2 x 3 1/2 x 1/4 3-3 1/2 x 3 1/2 x 1/4 8 Feet. The angle is 1/4-inch thick. in Inches 8 12 Span 3 Feet Steel Angles 2-3 x 3 x 1/4 3-3 x 3 x 1/4 Wood 2x8 2-2 x 4 2 x 12 2-2 x 6 2-3 x 3 x 1/4 3-3 x 3 1/4 2-3 x 3 x 1/4 3-3 1/2 x 3 1/2 x 1/4 7 Feet. which allows the two angle legs that project up into the brick to fit exactly into the 1/2-inch joint between the face and backing ties.FM 5-428 Chptr 9 Brick and Tile Masonry how to install a doubleness steel lintel in an 8-inch wall. Lintel sizes for 8-inch and 12-inch walls Wall Thickness.
Installing lintels in a 12-inch wall CORBELING 9-62. but the first projecting course can be a stretcher course if necessary. Corbeling usually requires various-sized bats ( a broken brick with one end whole. the other end broken off). Corbeling consists of brick courses projecting beyond the wall face to increase its thickness or form a self-supporting shelf or ledge (see Figure 9-33).FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-32. The portion of a chimney exposed to weather is frequently corbeled to increase its thickness for better weather resistance. No course should extend more than 2 inches beyond the course underneath it. and the total corbel projection should not be greater than the wall thickness. Use headers as much as possible. 9-35 .
FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-33. 9-36 . Constructing a corbeled brick wall 9-63. A well-constructed brick arch can support a heavy load. Make all mortar joints carefully and fill them completely with mortar. consult a qualified engineer. When the corbel must withstand large loads. mainly due to its curved shape. Corbel construction requires good workmanship for maximum strength. ARCHES 9-64. Figure 9-34 shows two common arch shapes.
Cut two pieces to the proper curvature and nail them to 2 by 2 spaces that provide a surface wide enough to support the brick. but it should not narrow to less than 1/4 inch at any point. BUILDING A TEMPLET 9-65.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-34. For arches spanning up to 6 feet. Using a templet to construct an arch You can obtain the templet dimensions from the construction drawings. Common shapes Brick arches require full mortar joints. Use wedges to hold 9-37 . As laying progresses. Note that the joint width is narrower at the bottom of the arch than at its top. make sure that the arch does not bulge out of position. Figure 9-35. Construct a brick arch over a temporary wood support called a templet (see Figure 9-35) that remains in place until the mortar sets. use 3/4-inch plywood to make the templet.
Parging means to plaster the back of the brick in the face tier with not less than 3/8 inch of rich cement mortar before laying the backing bricks. Do not change the position of a brick after the mortar begins to set. Figure 9-36. PREVENTING CRACKS 9-68. Sometimes a poor bond between the brick and the mortar causes cracks to form and sometimes mortar shrinkage is responsible. completely fill all head and bed joints with mortar. LAYING OUT THE ARCH 9-66. PARGING 9-69. Water does not usually penetrate brick walls through the mortar or brick. WATERTIGHT WALLS 9-67. Because you cannot plaster over mortar protruding from the joints. Parging the back of the face tier for watertightness 9-38 . You can reduce both the size and number of cracks between the mortar and the brick by tooling the exterior faces of all mortar joints to a concave finish. first cut all joints flush with the back of the face tier. but through cracks between the brick and the mortar. To obtain watertightness. Then drive out the wedges. Adjust the number of bricks and the joint spacing (not less than 1/4 inch) until the key brick is at the exact center of the curve. Lay out the arch carefully to avoid cutting the brick. Cracks are more likely to occur in head joints than in bed joints. The key or middle brick is the last one laid.FM 5-428 Chptr 9 Brick and Tile Masonry the templet in position until the mortar hardens enough to make the arch self-supporting. To determine how many bricks an arch requires. lay the templet on its side on level ground and set a trial number of bricks around the curve. Mark the positions of the bricks on the templet and use them as a guide when laying the brick. because this destroys the bond between the brick and mortar and a crack will result. Wet high-suction bricks and other bricks as necessary during hot weather so that they do not absorb too much moisture from the mortar and cause it to shrink. Figure 9-36 shows a good way to produce a watertight wall called parging or back plastering. Use an odd number of bricks so that the key or middle brick falls into place at the exact arch center or crown.
If the wall is subject to much groundwater. Walls can be waterproofed in three ways: q Bituminous mastic. construct tile drains or French drains around the wall base (see Figure 9-37). repair all cracks. If drainage tile is not available.FM 5-428 Chptr 9 Brick and Tile Masonry WATERPROOF WITH MEMBRANES 9-70. Before the coating sets. which is recommended for tuck-pointing in paragraph 9-90. To repair mortar joint cracks. A properly installed membrane adjusts to any shrinkage or settlement without cracking. You can improve the watertightness of above-grade brick walls by 9-39 . apply two coats of bituminous mastic to the exterior brick surface. CONSTRUCTING DRAINS 9-71. NOTE: Repair cracks in bricks the same way as cracks in concrete (see paragraphs 5-95 and 5-105). first chip out the mortar around the full width of the crack to a depth of about 2 inches. Figure 9-37. Before applying waterproof or portland-cement paints. fill the hole with prehydrated mortar. apply a coating of cement mortar made with enough water to form a thick liquid. or the surrounding soil does not drain well. q Waterproof paints. To make a below-grade foundation wall watertight. While the hole surfaces are still wet. Draining a wall around its foundation REPAIRING CRACKS 9-72. use a membrane to waterproof it. If a wall is subject to much water pressure. Carefully scrub the hole with clean water. USING WATERPROOF COATING 9-73. an 8-inch layer of coarse loose rock or stone will do the job. You can apply asphalt or coal tar pitch using a mop. This is called a French drain.
incinerators. The bricks in one course should lap those in the course underneath by one-half brick. Remember that any heat that migrates through the cracks between the fire bricks will damage the outside shell of the incinerator or furnace. do not use silica brick if it will be alternately heated and cooled. Dip the brick in the mortar. certain white and color waterproof paints. Make the mortar joints as thin as possible. covering all surfaces except the top bed. Varnish. however. Step 4. such as a water solution of sodium silicate. Step 3. and high-quality oil-base paints are also effective. but spraying reduces the paint's rain resistance. The outer shell probably consists of common brick or steel. use the following proedures: Step 1. TYPES 9-75. Use white-wash or calcimine-type brushes or a spray gun. called fire clay. This paint generally gives excellent results if you apply it when the wall is at least 30 days old. Mortar 9-77. and fit the bricks together tightly. FIRE-RESISTANT BRICK 9-74. and so forth. Fire brick requires thin mortar joints. Lay the brick and tap it firmly into place with a bricklayer's hammer. Obtain fire clay by grinding used fire brick. Stagger the head joints the same way you do in ordinary brick construction. or that withstand higher temperatures and are heavier and usually larger than common brick. q Silica bricks resist acid gases. Their standard size is 9 by 4 1/2 by 2 1/2 inches. Therefore. Portland-cement paint. Use type 2. Remove all efflorescence from the surface (see paragraph 9-95) and dampen the surface with a water spray before applying the paint. use fire-resistant brick to protect the supporting structure or outer shell from intense heat. neither of which has good heat resistance. LAYING FIRE BRICK 9-76. To line furnaces. waterproof paint. To lay fire bricks. The two types of fire-resistant brick are fire bricks and silica bricks. especially if the brick is subject to such high temperatures as those in incinerators. class A portland-cement paint and follow the manufacturer's instructions for mixing and applying it. Apply them according to the directions. Laying procedure 9-78. Use a mortar made from fire clay and water mixed to the consistency of thick cream. you should line most incinerators with fire brick rather than with silica brick. Step 2. Store the bricks in a dry place until you use them.FM 5-428 Chptr 9 Brick and Tile Masonry q applying a transparent. q Fire bricks are made from a special clay. 9-40 .
Make the weep holes simply by leaving the mortar out of the joint. HOLLOW 9-81. To prevent water penetration to the inner tier. Construction details of a cavity wall Rowlock 9-41 . Cavity 9-82. Instead of headers. It looks the same on the exterior as a solid wall without header courses (see Figure 9-38). The bottom of the cavity is above ground level. fitting them so close together that they fuse at the joints at high tempera-tures. Space them about a 24-inch interval. angle the ties downward from the inner to outer tier. A 2-inch cavity or air space between the two brick wythes drains any water that penetrates the outer tier. The air space also provides good heat and sound insulation. The two most important types of hollow walls are the cavity wall and the rowlock wall. The basic types of walls are: hollow and partition. TYPES OF WALLS 9-80. Lay silica bricks without mortar. Hollow walls consist of an inner and an outer wythe separated by an air space. metal ties are installed every sixth course on a 24-inch center that holds the two tiers together. They may be load-bearing or nonload-bearing walls. Stagger the head joints as you do in ordinary brick construction. Partition walls divide the interior space in a one-story building.FM 5-428 Chptr 9 Brick and Tile Masonry LAYING SILICA BRICK 9-79. It is drained by weep holes in the vertical joints in the first course of the exterior tier. Figure 9-38. A cavity wall is a watertight wall that can be plastered without furring or lathing.
three rowlock courses to every header course).FM 5-428 Chptr 9 Brick and Tile Masonry 9-83. The rowlock wall is not as watertight as the cavity wall. A partition wall that carries very little load requires only one wythe producing a wall 4 inches thick. and closures (K and l). because water will follow along any crack in the header course and pass through to the interior surface. head joints (h). Erect the corner leads first. A rowlock is a header laid on its face or edge. You can lay a wall of this thickness without headers. Construction details of a rowlock wall PARTITION 9-84. A rowlock also has a 2-inch cavity between the wythes as shown in Figure 9-39. cross joints (j). Lay the brick for hollow and partition walls as described starting in paragraph 9-29 for making bed joints (f). MANHOLES 9-86. and then build the wall between them. LAYING HOLLOW AND PARTITION WALLS 9-85. 9-42 . the bricks in the inner or backing tier are laid on edge. The manhole size largely depends on the sewer size. the face tier is loose like a common-bond wall having a full header course every seventh course. In this type of rowlock wall. Sewer systems require man-holes (see Figure 9-40) for cleaning and inspection. Figure 9-39. However. Manholes are either circular or oval to reduce the stresses from both water and soil pressures. A 4-foot diameter manhole is satisfactory for small. A header course ties the outer and backing ties together. For an all-rowlock wall. Use a line the same as for a common bond wall. Install a header course every fourth course (that is. lay the brick on edge in both the inner and outer tiers.
Construction details of a typical manhole are shown in view 2 of Figure 9-40. A qualified engineer should design any manholes over 15-feet deep. The wall thickness of a manhole depends on its depth and diameter. some irregularities in both brick position and mortar joint thickness are permissible. Use only headers for an 8-inch wall. Use a mason's level to make sure that all bricks in a particular course are level. Construction details of a sewer manhole WALL THICKNESS 9-87. You can use an 8-inch wall for manholes up to 8 feet in diameter and less than 15 feet deep. MANHOLE CONSTRUCTION 9-88. because it requires no form work. Figure 9-40. All joints should be either full or closure 9-43 . to make sure the brick rises to the same level all around. you can construct the walls more economically from brick. Span the manhole with a straightedge or place a mason's level on a straight surfaced 2 by 4 across the manhole. Although both the bottom and walls of a manhole are sometimes made from brick. However.FM 5-428 Chptr 9 Brick and Tile Masonry straight-line sewers. the bottom is normally made from concrete because it is easier to cast in the required shapes. but no line. Because the wall appearance is not important.
Figure 9-41. To reduce the manhole diameter to fit the frame and cover.or 12-inch wall. insert a steel bearing plate set in mortar under the beam. SUPPORTING BEAMS ON A BRICK WALL 9-89. Lay the first course on the mortar bed. Corbeling. let the beam bear on the full width of the inside tier. and place the base of the manhole frame in the bed. Spread a 1-inch mortar bed on top of the last course. Place a 1-inch mortar bed on the foundation. plaster the wall on the outside at least 3/8-inch thick with the same mortar used in laying the brick.FM 5-428 Chptr 9 Brick and Tile Masonry joints. Placing. corbel the brick inward as shown in view 2 of Figure 9-40 above. in case of fire. and embed them in a cross mortar joint. When a brick wall must support a steel beam. The following beams are used on brick walls. it will fall without damaging the wall above the beam. followed by the succeeding header courses. Note the wall tie. because wood can dry rot when completely encased in mortar. Figure 9-41 shows how to support a wood beam on a brick wall. For an 8. Protect the beam with a beam box (see Figure 9-41). When complete. Space the wrought-iron steps about every 15 inch vertically. q q q Laying the first course. The size of the bearing plate depends on the size of the beam and the load it carries. Keep mortar away from the beam as much as possible. q Steel Beams. q Wood Beams. A properly designed bearing plate prevents the beam from crushing the brick. Supporting a wood beam on a brick wall 9-44 . No brick should project more than 2 inches beyond the brick underneath it. Cut the end of the beam at an angle so that.
Use a chisel having a cutting edge about 1/2 inch wide. Mix the dry ingredients with just enough water to produce a damp mass of a consistency that retains its form when you compress it into a ball with your hands. and adequate flashing add little to the initial cost. PREPPING THE MORTAR JOINT 9-92. Before applying the acid. Remove mortar stains with an acid solution of one part commercial muriatic acid to nine parts water. most new brick walls still need some cleaning. no further joint wetting is required. Acid must be poured into the water. A well-constructed brick masonry wall requires little maintenance or repair.FM 5-428 Chptr 9 Brick and Tile Masonry MAINTAINING AND REPAIRING BRICK WALLS 9-90. If you use a water jet. proper joint finishing. using a forward motion to reduce the risk of forming air pockets. Before filling the joint. Prehydrating mortar greatly reduces the amount of shrinkage. It can be more expensive to repair old masonry properly than to completely remove and replace just the disintegrated portion. PREPARING MORTAR FOR TUCK-POINTING 9-93. Step 1. not the water into the acid. Allow the mortar to stand for at least 1 hour. If not. Tuck-pointing during routine maintenance means to cut out all loose and disintegrated mortar to a depth of at least 1/2 inch and replace it with new mortar. To stop leakage. but not more than 2 hours. However. remove all dust and loose material with a brush or a water jet. and replace it with new mortar. moisten the joint surfaces. After cutting out the defective mortar. Push the mortar into the joint in one direction only from the starting point. Then pack the prepared prehydrated mortar into the joint tightly in thin layers about 1/4 inch thick. and finish them to a smooth concave surface using a pointing tool. TUCK-POINTING 9-91. Use portland--cement-lime prehydrated Type S mortar or prehydrated prepared mortar made from type II masonry cement. but reduce maintenance cost throughout the life of the masonry. Remove large mortar particles adhering to brick with a putty knife or chisel. A skilled bricklayer can build a masonry wall that is almost free from mortar stains. thoroughly soak the masonry surface with water to prevent 9-45 . CLEANING NEW BRICK AND REMOVING STAINS 9-95. allow the moisture used in preparing the joint to absorb. cut out all the mortar in the affected area. Good mortar. FILLING THE JOINT 9-94. Filling a joint with mortar is called repointing and is done with a pointing trowel. Then mix the mortar with enough water to produce a stiff. but workable consistency.
apply a transparent waterproofing paint to the surface to help prevent future soiling by soot and dust. Use one garden hose to carry water to the cleaning nozzle and 9-46 . SANDBLASTING 9-97. STEAM CLEANING WITH WATER JETS 9-98. the salt remain. Step 3. which changes the appearance of the wall. It consists of soluble salts leached from the brick by penetrating water that dissolves the salt in the brick. Rough-textured brick is more difficult to clean than smooth-textured brick. Use a portable. Never sandblast glazed surfaces. Apply the acid solution with a long-handled stiff-fiber brush. if simply scrubbing the wall with water and a stiff brush does not remove the efflorescence. steam cleaning with water jets. Sandblasting consists of using compressed air to blow hard sand through a nozzle against a dirty surface. This removes grime effectively without changing the surface texture. Moreover. Sometimes you cannot clean rough-textured brick without removing part of the brick itself. and wear goggles to protect your eyes. Take all precautions to prevent the acid from getting on your hands. Make sure that you remove all acid before it can attack the mortar joints. q Equipment. However. truck-mounted boiler to produce the steam at a pressure ranging from 140 to 150 psi. sandblasting usually cuts so deeply into the mortar joints that you may have to repoint them. arms. The disadvantage of sandblasting is that it leaves a rough-textured surface that collects soot and dust. thereby removing enough of the surface to eliminate the stain. The principal ways to clean old brick masonry are sandblasting. Step 2. or using cleaning compounds. and then wash it down immediately with clear water. q Procedure.FM 5-428 Chptr 9 Brick and Tile Masonry the stain from being drawn into the brick pores. Many cleaning compounds that do not affect the brick will damage the mortar. Because efflorescence requires the presence of both water and salts. CLEANING OLD BRICK 9-96. Place a canvas screen around the scaffold to salvage most of the sand. The velocity of the steam and water spray as it strikes the surface is more important than the volume of the spray. Protect door and window frames. which gives steam cleaning an advantage over sandblasting. Steam cleaning means to project a finely divided spray of steam and water at high velocity against a dirty surface. The type of brick and the nature of the stain will determine which method you use. Efflorescence is a white deposit that forms on the surface of brick walls. proper brick selection and a dry wall will keep it to a minimum. or clothing. Removing any efflorescence. When the water evaporates. Scrub an area of 15 to 20 square feet with the acid solution. you can remove it with the acid solution described above for cleaning new masonry. Each cleaning nozzle requires about a 12-horse-power boiler. After sandblasting.
After removing the coating. Be careful not to cut into the surface. in an enameled pan. You can remove white-wash. Leave the remover on until the coating is soft enough to scrape off with a putty knife. varnishes. After removing the deposits.FM 5-428 Chptr 9 Brick and Tile Masonry q q another to supply rinse water. wash down the surface with water and steam and clean it again. You can use one of several cleaning compounds. then. Mix seven parts lime-free glycerin into a solution of one part sodium citrate in six parts lukewarm water. wash down the wall with clean water until you remove the acid completely. or paint coatings with a solution of one part acid to five parts water. Another solution is 1 1/2 pounds of caustic soda in 1 gallon of hot water. Adjust the steam and water valves until you obtain the most effective spray. To aid cleaning action. depending on the nature of the stain. enamels. CLEANING COMPOUNDS 9-99. q Blasting and torching. Use steel scrapers or wire brushes to remove any hardened deposits that remain after steam cleaning. The following are effective paint removers: q Commercial. Hand tools. shellacs. Scrape off the paste when it dries. or glue sizing. Next. mix 12 ounces of chloride of lime in enough water 9-47 . sodium bi-carbonate. Use a solution of 2 pounds of trisodium phosphate in 1 gallon of hot water. Dissolve 2 pounds of trisodium phosphate in 5 quarts of water. calcimine. Additives. Sandblasting or burning off with a blowtorch will also remove paint. REMOVING MISCELLANEOUS STAINS 9-101. Rinse it immediately with clean water before moving to the next area. PAINT REMOVERS 9-100. When using commercial paint removers. Repeat the procedure until the stain disappears. q Chemical. add sodium carbonate. the manufacturer's in-structions should be followed. Reduce a lot of the salt or efflorescence remaining on the surface by washing it down with water before and after steam cleaning. wash down the surface with water. Experiment to determine the best angle and distance from the wall to hold the nozzle. You can prevent this by thoroughly wetting the surface before applying the solution. Apply paint remover with a brush to remove oil paint. q Tobacco stains. The following are procedures for removing different types of stains: q Iron stains. Add whiting or kieselguhr to make a thick paste and apply it to the stain with a trowel. Use fiber brushes to scrub the surface with the solution while it is still foaming. Most cleaning compounds contain salts that will cause efflorescence if the cleaning solution penetrates the surface. Pass the nozzle back and forth over no more than a 3-square-feet area at one time. or trisodium phosphate to the water entering the nozzle.
Then mix the trisodium phosphate with the lime paste in a 2-gallon stoneware jar. Remove the paste and wash down the surface with clean water. Add ammonia water and stir the solution to obtain a thick paste. FLASHING 9-102. Corrugated copper flashing sheets produce a good bond with the mortar.FM 5-428 Chptr 9 Brick and Tile Masonry q q q to make a smooth thick paste. If a slight stain still remains after several applications. Several applications may be necessary. Mix one part ammonium chloride (salammoniac) in dry form to four parts powdered talc. Copper is best. and their replacement cost is greater than the initial cost of installing high-quality flashing. Cover the container when you are finished to prevent evaporation. Flashing can be made from copper. They also make interlocking watertight joints at points of overlap. They will probably require periodic replacement in permanent construction. Make a solution of 1 gallon trisodium phosphate to 1 gallon of water. 9-48 . and apply it to the stain with a trowel followed by washing the surface. stiff paste made from trichlorethylene and powdered talc. and allow it to dry for 24 hours. Flashing is an impermeable membrane placed in brick masonry at certain locations to exclude water or to collect any moisture that penetrates the masonry and direct it to the wall exterior. Oil stains. Copper and bronze stains. Then wash down the surface with clear water. Apply a smooth. Where chimneys pass through the roof. aluminum. Apply the paste to the stain with a trowel. but not as durable. Use the paste only in a well-ventilated space because its fumes are harmful. Smoke stains. The flashing edges should turn upward as shown in Figure 9-42 to prevent drainage into the wall. draw off the clear liquid and dilute it with an equal amount of water. although it stains the masonry as it weathers. Install flashing at both the head and sill of window openings and at the intersection between a wall and roof. the flashing should extend completely through the chimney wall and turn upwards 1 inch against the flue lining. wash down the surface and then follow the procedure described above for removing tobacco stains. adding enough whiting to form a paste. Always install flashing in mortar joints. or bituminous roofing paper. lead. You can provide drainage for the wall above the flashing either by placing 1/4-inch cotton-rope drainage wicks at 18-inch spacings in the mortar joint just above the flashing or placing dowels in the proper mortar joint as you lay the brick and then remove them to make drainage holes. Bituminous roofing papers are cheapest. and allow it to dry. Use lead-coated copper if such staining is unacceptable. Trowel the paste over the stain in a layer 1 1/2 inch thick. Make a stiff paste by mixing the clear liquid with powdered talc. PLACEMENT 9-103. When the lime settles.
and then push the flashing sheet down firmly into the mortar. Figure 9-43 shows how to install flashing between the roof and the wall to prevent leakage at the intersection. Using the following steps to install flashing: Step 1. and then force the brick or sill onto the top of the flashing. Fit and caulk the upper end of the flashing into the groove of the raggle block as shown in Figure 9-43. then bends behind the face tier and over the top of the lintel. Note that the flashing fits under the face tier of brick at the steel lintel. Spread a 1/2-inch mortar bed on the flashing. Installing flashing at window opening INSTALLATION 9-104. Step 2. Spread a 1/2-inch mortar bed on top of the brick.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-42. Step 3. Figure 9-42 above shows the proper flashing installations at both the head and the sill of a window. 9-49 .
Careless materials storage can cause time delays and/or contribute to poor workmanship. Heat both water and sand to a temperature not exceeding 160oF. prevent future wall leakage by-q Storing materials properly. q Heating masonry units.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-43. Make sure that the temperature of the mortar--when you use it--is at least 70oF but not more than 120oF. q Taking special precautions during placement. and raise them about 1 foot above the ground so that you can supply heat to keep the mortar warm after mixing. completely cover all masonry units and mortar materials with tarpaulins or building paper. Instead. Masonry walls built during cold weather may leak. 9-50 . HEATING MORTAR INGREDIENTS 9-107. Use steel mortar boxes on small jobs. because either the mortar froze before it set or the materials and walls were not adequately protected against freezing temperatures. STORING MATERIALS 9-106. because you must remove all ice and snow and thaw masonry units before construction can proceed. During cold weather. Never add salt water to mortar to lower its freezing point. Flashing installation at intersection of roof and walls FREEZE PROTECTION DURING CONSTRUCTION 9-105. q Protecting completed work. q Heating mortar ingredients. Store them on plank platforms either thick enough or raised high enough to prevent moisture absorption from the ground.
Number Mortar. MATERIAL QUANTITIES REQUIRED 9-112. respectively.44 .08 12. Table 9-6. If you use high-early-strength cement. because little or no bond will exist between the mortar and units when the base thaws. desired rate of construction. To prevent the warm mortar from cooling suddenly as it contacts the cold bricks. and the prevailing weather conditions all determine the amount of protection and the type of heat necessary to maintain above-freezing temperatures within the wall until the mortar sets properly.49 . Job layout. but it does increase the rate of strength gain. sprinkle any high-suction brick with warm water just before you lay it. In below-freezing weather. Number Mortar. If the covering comes off and ice or snow collects on the wall top.2 18. Square of in of in of in of in Feet Bricks Cubic Bricks Cubic Bricks Cubic Bricks Cubic Feet Feet Feet Feet 1 9-51 6. or for at least 72 hours for Type N mortar. provide inside brick storage so that you can supply heat at minimum expense.65 . Never lay masonry units on snow. See Table 9-6 for the quantities of brick and mortar required for various masonry wall thickness. in Inches Wall 4 8 12 16 Area in. preheat all masonry units to about 40oF whenever the outside temperature is below 18oF.32 24. Note that the use of high-early-strength cement in a mortar does not alter the setting rate much. When heat is required. thereby providing greater resistance to further freeze damage. the brick temperature when you lay it should be above 40oF on both sides of the masonry for at least 48 hours for Type M or S mortar. HEATING MASONRY UNITS 9-109. reduce these time periods to 24 and 48 hours. How you protect masonry from freezing varies with weather conditions and the individual job.or ice-covered mortar beds. LAYING PRECAUTIONS 9-110. remove it with live steam before continuing. Keep the tops of unfinished walls carefully covered whenever work stops. Number Mortar. PROTECTING COMPLETED WORK 9-111.FM 5-428 Chptr 9 Brick and Tile Masonry CONSIDERING TEMPERATURE VARIATIONS 9-108.33 . This requires careful planning and timing. Quantities of materials required for brick walls Wall Thickness. Number Mortar.17 . If the outside air temperature is below 40oF.
094 12.3 1.702 4. 9-52 . it is reinforced with steel when subject to tensile stresses.398 8.7 617 1. The same brick is used for reinforced brick masonry as for ordinary brick masonry.932 6. Like concrete construction. MATERIALS 9-115.234 1. a 3/8-inch-thick joint uses 80 percent of these quantities.465 4.253 19. and footings. The design of such structures by qualified engineers is similar to that of reinforced concrete structures.325 14. SECTION IV. the reinforcing steel is placed in either the horizontal or vertical mortar joints of beams.650 4.490 3.631 9.851 2. Because brick masonry in tension has low strength compared with its compressive strength. and foundations are reinforced the same as in concrete construction.000 61.5 2.085 3.553 6.792 16.8 8 16 24 32 40 48 56 64 72 80 123.466 3. APPLICATIONS 9-114. However. columns.2 32 64 96 128 160 192 224 256 288 320 246. When added strength is needed.698 5. Materials used for reinforced brick are-q Brick.641 18.790 17.468 3. Reinforced brick structures can resist earthquakes that would severely damage nonreinforced brick structures. brick walls.930 7. beams.233 2.860 12. it should have a compressive strength of at least 2.547 7. columns.FM 5-428 Chptr 9 Brick and Tile Masonry 10 100 200 300 400 500 600 700 800 900 1.396 9.330 2 20 40 60 80 100 120 140 160 180 200 184.864 10. REINFORCED BRICK MASONRY APPLICATIONS AND MATERIALS 9-113.319 4.185 24.170 .936 5.970 12.849 3.395 9.500 pounds per square inch.4 44 88 132 176 220 264 308 352 396 440 NOTE: Quantities are based on a 1/2-inch-thick mortar joint. walls.943 14.9 1.165 7.245 11.699 4. a 5/8-inch-thick joint uses 120 percent of these quantities.720 22.
This provides 1/16 inch of mortar between the brick surface and the bar. following the same procedure as laying brick without reinforcing steel. Insert the lower leg under--and contacting--the horizontal bars. Hold vertical bars in the vertical mortar joints with wood templets having holes drilled at the proper bar spacing.FM 5-428 Chptr 9 Brick and Tile Masonry q q q Steel. soft-annealed iron wire to tie the reinforcing steel. 9-53 . and then push them down into position. PLACING THE STEEL 9-118. q Vertical bars. Most stirrups are Z-shaped as shown in Figure 9-44 to fit the mortar joints. Embed all reinforcing steel firmly in mortar. smooth it out until you produce a second bed joint of the proper thickness. CONSTRUCTION METHODS 9-116. q Spacing. because masonry construction requires many sharp bends. Spread more mortar on top of the bars. or by wiring them to horizontal bars. q Stirrups. Then lay the brick up around the vertical bars. Lay the next course in this mortar bed. q Horizontal bars. which requires a thicker joint at that point. Lay the brick the same way as ordinary brick masonry. Use Type N mortar for its high strength. with mortar joints 1/8 inch thicker than the diameter of the reinforcing bar. Wire. Do not use high-grade steel except in emergencies. Use 18-gage. large steel bars require mortar joints thicker than 1/2 inch. LAYING REINFORCED BRICK 9-117. Lay horizontal bars in the mortar bed. The reinforcing steel is the same as that in reinforced concrete and is fabricated and stored the same way. Mortar. The minimum center-to-center spacing between parallel bars is 1-1/2 times the bar diameter. Thus. Reinforcing steel can be placed in both horizontal and vertical mortar joints.
BEAMS AND LINTEL CONSTRUCTION 9-120. 12. reinforced brick beams and lintels--which act as beams--require formwork for the same reason that reinforced concrete beams do. Lay the first course on the form using full head joints. or 16 inches. q When a beam joins a wall or another beam. The following procedures will be used in beam construction: Step 1. that is 4. columns. mortar joint thickness. beam width usually equals the wall thickness. q Wait at least 10 days before removing the form from the beam underside. However. This allows the lumber to swell and makes form removal easy. Reinforced brick-masonry walls. BEAM DIMENSIONS 9-121. q The form consists only of support for the underside of the beam. The form for the beam underside is the same and is supported the same as that for concrete beams. cut the form short by 1/4 inch. Lintels can be made of steel. 8. Reinforced brick-masonry beam construction USING FORMWORK 9-119. and fill the gap with mortar.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-44. Beam depth should not exceed approximately three times its width. no side formwork. However. and the load that the beam will support. and footings need no formwork. Lintels are placed above the windows and doors to carry the weight of the wall above them. but no bed joint (see 9-54 . BEAM CONSTRUCTION PROCEDURES 9-122. Beam width and depth depend upon brick dimensions. or wood. precast reinforced concrete beams.
Figure 9-45. in Feet 6 9 2 3 1/4 1/4 9-55 . Table 9-7 below gives the number and diameter of bars required for different width wall openings. Step 4. and embed the bars. LINTEL CONSTRUCTION 9-123. Be sure to center the stirrup in the vertical mortar joint. Then lay the remaining courses in the normal way. Step 2. Quantities of bars required for lintels Width of Wall Bar Quantity Bar Diameter. place the reinforcing steel. Reinforced brick-masonry lintel construction Table 9-7. Place the bars in the first and fourth mortar joints above the opening (see Figure 9-45). Step 5. Slip the legs of any stirrups under the horizontal bars as shown in Figure 9-44. After properly positioning the stirrups and the horizontal bars. and smooth its surface. three or four bricklayers must work on one beam to spread the bed-joint mortar for the entire course. and lay the brick before the mortar sets. or less if you must maintain a 1/2-inch mortar joint. They should extend 15 inches into the brick wall on each side of the opening. See paragraph 9-56 for how to place the wall above a window or door opening. The steel bars should be 3/8 inch in diameter. Step 3. Spread a mortar bed about 1/8 inch thicker than the diameter of the horizontal reinforcing bars on the first course. spread more mortar on the bed joints if necessary. Often. in Inches Opening. Lay all bricks for one course before proceeding to the next course to ensure a continuous bond between the mortar and steel bars.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-44).
spread on the subgrade. Reinforced brick-column footings are usually square or rectangular as shown in Figure 9-47. 9-56 . or column and are required to distribute the load equally. place one layer in the second mortar joint. 9-125. which is accepted practice for small bars. and reduce the bar spacing in this joint. Footings are the enlargements at the lower end of a foundation wall. but transfer stress from one to the other. Large footings usually require reinforcing steel because they develop tensile stresses. Figure 9-46 shows a typical wall footing with steel dowels extending above it to tie the footing and wall together. WALL FOOTING 9-126. The dowels not only anchor the column to the footing. The number 3 bars running parallel to the wall prevent perpendicular cracks from forming. Note that both layers of horizontal steel are in the first mortar joint.FM 5-428 Chptr 9 Brick and Tile Masonry 12 3 3/8 FOUNDATION FOOTINGS 9-124. When using large bars. Reinforced brick-masonry-wall footing construction COLUMN FOOTING 9-127. Figure 9-46. pier. As in all brick foundations. lay the first course in a mortar bed about 1 inch thick.
fill the core and any space around the reinforcing bars with mortar. After laying each course. Then push any necessary bats into the mortar until they are completely embedded. Install 3/8-inch diameter steel hoops or ties at every course (see Figure 9-48) to bold bars in place. Reinforced brick-masonry-column footing construction COLUMNS AND WALLS 9-128. q q Holding steel in place. Slip the necessary number of hoops over the dowels and fasten them temporarily some distance above the course being laid. You can use brick bats in the column core or wherever it is inconvenient or impossible to use full-size bricks. and smooth it out before laying the next course. When the column footing is complete. Use circular hoops whenever possible. Lap-weld their ends. 9-57 . 9-129. Load-carrying capacity increases when brick columns and walls have steel reinforcement. Hold the tops of the dowels in position either with a wood templet or by tying them securely to a hoop near the top of the column. tie the reinforcing steel to the dowels projecting from the footing.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-47. but within your reach. At least 1 1/2 inches of mortar or brick should cover the reinforcing bars. You do not need to wire the hoops to the dowels. Laying the brick. Lay the brick as described in paragraph 9-20. Now spread the next mortar bed and repeat the procedure. Place the hoops in a full mortar bed. or bend them around the reinforcing bars as shown in Figure 9-48.
Use the same size bars as in the rest of the wall. STRUCTURAL CLAY-TILE MASONRY STRUCTURAL CLAY TILE 9-131. and let them extend 15 inches. because you must embed the entire bar in mortar at one time. you must lay all brick in one course between the corner leads before laying any other brick. fill all spaces around the reinforcing bars with mortar. Place the bars as described in paragraph 9-117. 9-58 . The horizontal bars in the remaining wall should overlap the corner bars by the same 15 inches. Structural clay tile is either a hollow or cored burned-clay masonry unit having cores that are parallel either in the vertical or horizontal direction. Reinforce brick masonry walls with both horizontal and vertical bars. The manufacturing process and the type of clay used are the same as it is for brick. Figure 9-49. Place the reinforcing bars in corner leads as shown in Figure 9-49 below. Corner lead for reinforced brick masonry wall SECTION V. As you lay the remaining brick. q Laying the remaining wall. As for beams. Then wire the vertical stirrups to the dowels projecting out of the wall footing. Reinforced brick-masonry-column construction 9-130.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-48. q Constructing corner leads.
These stretcher units are made by forcing a plastic clay through special dyes. whereas end-construction tile has 9-59 . Side-construction tile has horizontal cells. Figure 9-50 shows several common types and sizes. the external wall is called a shell. The amount of burning depends upon the tile grade. Corner lead for reinforced brick masonry wall 9-133. Hollow masonry units made from burned clay or shale are usually called simply clay tile. The hollow spaces in the tile are called cells.FM 5-428 Chptr 9 Brick and Tile Masonry 9-132. and the partitions between cells are called webs. 9-134. The shell should be at least 3/4 inch thick and the web 1/2 inch thick. Figure 9-50. then cutting the tiles to size and burning them the same way as brick.
Load-bearing structural clay tile further subdivides into three categories: load-bearing wall tile.Grade SS (select sized or ground edge) is suitable for uses requiring very small variations in face dimensions. Use this tile where you need a stainproof. NONLOAD BEARING 9-60 q . It is available in many colors and produces a durable wall having a pleasing appearance. . 9-135. Headers bond the facing or outer tier to the backing tile. and glazed facing. q Structural facing tile is divided into two classes.Grade S (select) is suitable for use with comparatively narrow mortar joints. structural facing tile. Ceramic glazed structural facing tile has an exposed surface of either a ceramic or salt glaze. facing. Grade LBX can be used in masonry exposed to weathering with no facing material. based on the thickness of the face shell: standard and special duty.Type I is suitable for general use where only one finished face will be exposed. easily cleaned surface. Ceramic glazed facing tile is divided into two types and two grades: . fireproofing tile. and both are available in the types described below. although inferior in quality to Type FTX.FM 5-428 Chptr 9 Brick and Tile Masonry vertical cells. and screen tile. and ceramic glazed structural facing tile. The ASTM grades each of these classes by factors affecting appearance. plaster. Load-bearing tile has three types. The two basic categories of structural clay tile--load-bearing and nonload-bearing--differ in their characteristics.Type FTX is suitable for both exterior and interior walls and partitions.Type FTS. or other material. stone. 9-137. or a clay coating. is suitable for both exterior and interior walls where some surface finish defects are not objectionable. The ASTM covers two grades of wall and back-up tile based on weather resistance. LOAD BEARING 9-136. divided by use: wall. . q Back-up tile for backing up combination walls of brick or other masonry in which both the facing and the backing support the wall load. . Grade LB is suitable for general construction that is not exposed to weathering. Neither is better than the other. or exposed to weathering but protected by at least 3 inches of facing. Load-bearing wall tile includes-q Wall tile for constructing exposed or faced load-bearing walls. This tile carries the entire load. . including the facing of stucco. Nonload-bearing structural clay tile further subdivides into three categories: nonload-bearing partition and furring tile.Type II is suitable for use where the two opposite finished faces will be exposed. . It has an excellent appearance and is easy to clean. The inside face is scored so that you can plaster it without lath.
. and shapes. . Besides the standard units shown in Figure 9-50 above you can order special clay tile units to use at windows.5 8-inch thick wall and 8 x 5 x 12-inch tile Number of Tiles 2. columns. freezing. Quantities of materials required for side construction of hollow clay-tile walls 4-inch thick wall and 4 x 5 x 12-inch tile Wall Area. . Nonload-bearing tile include three types: q Nonload-bearing partition and furring tile.0 18 27 q q 9-61 . in Square Feet 1 10 100 200 300 Number of Tiles 2. sizes. .Grade NE is suitable for interior use only.9 9.5 9. Screen tile is divided into two types and three grades: .45 4. door openings.Type STX has an excellent appearance and minimum size variation. Consult a manufacturer's catalog for any special units you need. and in a limited number of colors.Furring tile is suitable for lining the wall interiors to provide both a plaster base and an air space between plaster and the wall. Tables 9-8 and 9-9 below give the number of structural clay tiles--both side construction and end construction--and the amount of mortar required for walls of different thickness covering varying areas.FM 5-428 Chptr 9 Brick and Tile Masonry 9-138. . in Cubic Feet .Grade SE has high resistance to weathering. and beams.Grade ME has moderate resistance to weathering.1 21 210 420 630 Mortar. QUANTITIES OF MATERIALS REQUIRED 9-140. Fireproofing tile protects structural members including steel girders.Type STA varies more in size.045 . scored. The surfaces may be smooth. and thawing. SPECIAL UNITS 9-139.09 . in Cubic Feet .0 13.1 21 210 420 630 Mortar. Table 9-8. or roughened. Screen tile is available in a large variety of patterns. and at corners. .Partition tile is suitable for constructing nonload-bearing interior partitions or for backing nonload-bearing combination walls. combed.
025 .3 93 186 279 372 465 558 651 774 837 930 .050 1. Table 9-9.890 2.8 14.890 2.0 17.6 7.93 9. of Tiles in of Tiles in of Tiles in of Tiles in in Cubic Cubic Cubic Cubic Square Feet Feet Feet Feet Feet 1 10 100 200 300 400 500 600 700 800 900 1.260 1.6 24.2 44.36 3.5 25. Number Mortar.260 1. Number Mortar.3 93 186 279 372 465 558 651 774 837 930 .0 31.4 34.680 1.680 1.000 840 1.9 9.4 18.2 10.036 .470 1.100 18.3 93 186 279 372 465 558 651 744 837 930 .06 .0 .5 20.5 36.0 7.049 .0 40.93 9.2 28.0 21.25 2.4 36.0 22.1 49.0 12.3 39.5 15.0 . Area. Quantities of materials required for end construction of hollow clay-tile walls 4-inch thick wall and 4 x 12 x 12inch tile 6-inch thick wall and 6 x 12 x 12inch tile 8-inch thick wall and 8 x 12 x 12inch tile 10-inch thick wall and 10 x 12 x 12inch tile Wall Number Mortar.3 93 186 279 372 465 558 651 744 837 930 .100 36 45 54 63 72 81 90 NOTE: Quantities are based on 1/2-inch thick mortar joints.0 .5 5.5 27.8 32.93 9.000 .5 29.050 1.6 25.49 4.6 6 12 18 24 30 36 42 48 54 60 9-62 .7 19.470 1.5 10.FM 5-428 Chptr 9 Brick and Tile Masonry 400 500 600 700 800 900 1.93 9. Number Mortar.0 840 1.5 45.0 22.8 14.
the abrasion resistance of clay tile depends mainly on its compressive strength. you can improve it by plastering the wall surface. because hollow cell size varies.700oFF within that hour.and sound-insulating properties. Other physical properties are-q Abrasion resistance. the greater its resistance to wear. actual tile weight depends on the manufacturer and the type. Its sound penetration-resistance compares favorable with that of solid masonry walls. Tile masonry has low tensile strength--in most cases less than 10 percent of its compressive strength. However. Structural clay facing tile has excellent resistance to weathering. use only portland-cement-lime mortar or mortar prepared from masonry cement. A 6-inch tile wall weighs approximately 30 pounds per square foot. Structural clay-tile walls have much less fire resistance than solid masonry walls. if the fire's temperature does not exceed 1. Because of the dead air space in its cells. When masonry is exposed to weather. Like brick. You can predict that tile masonry will have a minimum compressive strength of 300 pounds per square inch based on the cross section. The stronger the tile. q Heat. CONSTRUCTION DETAILS AND METHODS 9-142. whereas a 12-inch tile wall weighs approximately 45 pounds per square feet. q q q q Finishing joints (paragraph 9-37). q Fire resistance. The compressive strength of an individual clay tile depends on its ingredients and the method of manufacture. Partition walls 6 inches thick will resist a fire for one hour. Tile absorbing up to 16 percent of its weight of water satisfactorily resists freezing and thawing effects. but abrasion resistance decreases as the amount of absorbed water increases. q Weather resistance. However. Watertight walls (paragraph 9-67). q Weight. Structural clay-tile weighs about 125 pounds per cubic foot. PHYSICAL CHARACTERISTICS OF STRUCTURAL CLAY TILE STRENGTH 9-141. Bricklayer's duties (paragraph 9-38). but is somewhat less.FM 5-428 Chptr 9 Brick and Tile Masonry NOTE: Quantities are based on 1/2-inch thick mortar joints. Freezing and thawing produces almost no deterioration. Refer to the paragraphs listed to obtain specific information applicable to structural clay-tile construction: q Tools and equipment (paragraphs 7-4 and 7-5). plus the thickness of its shell and webs. 9-63 . Bricktender's duties (paragraph 9-39). clay tile has better heat-insulating qualities than solid unit walls.
You can use structural clay tile for either load bearing or nonload-bearing exterior walls. Structural clay tile can be used as a backing unit for a brick wall. use both hands to push it into the mortar bed until it is properly positioned. q Exterior walls. the position of a tile in one course does not match the tile underneath it. Because a clay tile unit is heavy. The general procedure for making mortar joints for structural clay tile is the same as for brick. Nonload-bearing partition walls ranging from 4 to 12 inches thick are often built of structural clay tile. Spread the mortar about 3 feet ahead of laying the tile. 9-64 . Use the procedure described in paragraph 9-33 for making closure joints in brick masonry. q Partition walls.FM 5-428 Chptr 9 Brick and Tile Masonry q q q q Maintaining and repairing brick walls (paragraph 9-90) Cleaning new brick and removing efflorescence (paragraph 9-95). and any mortar you spread on them is useless.and sound-insulating properties. It is suitable for both below-grade and above-grade construction. as shown in view 2 of Figure 9-51. q Backing for brick walls. To make a bed joint. lightweight. The head joint need not be solid like a head joint in brick masonry. The mortar joint should be about 1/2 inch thick. depending upon the type of construction. Freeze protection (paragraph 9-105). Because the head joints in clay-tile masonry are staggered. q Head joint. They are easy to construct. Use enough mortar that it squeezes out of the joints. the webs do not make contact. and have good heat. APPLICATIONS 9-143. The three practical uses for structural tile are discussed below. Cleaning old brick (paragraph 9-96). MORTAR JOINTS 9-144. Therefore. q Closure joints. but not on the webs (see view 1 of Figure 9-51 below). Form the head joint by spreading plenty of mortar along each tile edge. Mortar joints for end-construction units are described as follows: q Bed joint. spread 1 inch of mortar on the bed tile shells. and then cut the excess off with a trowel. unless it is subject to weather.
9-65 . approximately 3 feet ahead of laying the tile.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-51. Laying end-construction clay tile 9-145. Spread as much mortar as will adhere on the interior shell of the bed tile and on the exterior shell of the unit you are placing (see view 2 or Figure 9-52). Cut off the excess mortar.Method B.Method A. You need not make a furrow as you must for brick bed joints. q Head joint. Use one of the two following methods: . . Spread as much mortar on both edges of the tile as will adhere (see view 1 of Figure 9-52). q Mortar joint thickness. Mortar joints for side-construction units are described as follows: q Bed joint. Spread the mortar about 1 inch thick. depending upon the type of construction. Make the mortar joints about 1/2 inch thick. Then push the tile into place and cut off the excess mortar. Then push the tile into the mortar bed against the tile already laid until it is properly positioned.
This determines the number of bricks in one course. Lay the tile bed joint so that the top of the tile is level with every second brick course. the thickness of the tile bed joint depends upon the thickness of the brick bed joint. Figure 9-53. the first brick course in the corner lead is the same as the first course of the corner lead for a solid 8-inch brick wall. Therefore. Then lay the first tile course as shown in view 2 of Figure 9-53. As shown in view 1 of Figure 9-53. except that you lay one more brick next to brick (p) as shown in step 5 of Figure 9-22. Lay all the bricks for the corner lead before laying any tile. Laying side-construction clay LAYING AN 8-INCH BRICK WALL WITH A 4-INCH HOLLOW-TILE BACKING 9-146. the brick wall has six stretcher courses between the header courses. When laying an 8-inch brick wall with a 4-inch structural hollow-tile backing. The side-construction backing tile is 4 by 5 by 12 inches in size. Complete the corner lead as shown in view 3.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-52. LAYING THE CORNER LEADS 9-148. Lay out the first brick course temporarily without mortar. LAYING OUT THE WALL 9-147. 9-66 . as described in paragraph 9-44. The 5-inch tile height equals the height of two brick courses plus a 1/2-inch mortar joint.
Laying a corner lead with hollow-tile backing LAYING AN 8-INCH STRUCTURAL CLAY-TILE WALL 9-149. A soap is a thin end-construction tile.FM 5-428 Chptr 9 Brick and Tile Masonry Figure 9-53.by 5. Use 8. 9-67 . You can insert a 2.by 5.by 8-inch soap at the corners as shown in Figure 9-54 below.by 12-inch side-construction tile in a half-lap bond to construct an 8-inch structural clay-tile wall.
FM 5-428 Chptr 9 Brick and Tile Masonry
Figure 9-54. Constructing the corner lead of an 8-inch structural clat-tile wall LAYING OUT THE WALL 9-150. Follow the procedure described inparagraph 9-43. LAYING THE CORNER LEADS 9-151. Lay tiles a and b first (see Figure 9-54), and check their level as you lay them. To avoid exposing open cells on the wall face, use either end-construction tile for corner tiles b, g, and h, or a soap as shown in Figure 9-54. Lay tile b so that it projects 6 inch from the inside corner, as shown, to start the half-lap bond. Now lay tiles c and d, and check their level as you lay them. Next, lay tiles e and f, and check their level. Lay the remainder of the corner tile, and check the level of each as you lay it. After erecting the leads, lay the wall between them using a line.
FM 5-428 Appendix A
Appendix A
Conversion Table
Metric To English Multiply By To Obtain Length Centimeters Meters Meters Kilometer Kilometers 0.0394 Inches 3.28 Feet 1.094 Yards 0.621 Miles (stat.) 0.540 Miles (Naut.) Inches Feet Yards Miles (stat.) Miles (naut.) Area Square centimeters Square meters Square meters 0.1550 Square inches 10.76 Square feet 1.196 Square yards Square inches Square feet Square yards Volume Cubic centimeters Cubic meters Cubic meters Milliliters
English to Metric Multiply By To Obtain
2.54 Centimeters 0305 Meters 0.914 Meters 1.609 Kilometers 1.853 Kilometers
6.45 Square centimeters 0.0929 Square meters 0.836 Square meters
0.610 Cubic inches 35.3 Cubic feet 1.308 Cubic yards 0.0338 US liq ounces
Cubic inches Cubic feet Cubic yards US liq ounces
16.39 Cubic centimeters 0.0283 Cubic meters 0.765 Cubic meters 29.6 Milliliters
FM 5-428 Appendix A
Liters Liters
1.057 US liq quarts 0.264 US liq gallons
US liq quarts US liq gallons Weight
0.946 Liters 3.79 Liters
Grams Kilograms Metric tons Metric tons
0.0353 Ounces 2.20 Pounds 1.102 Short tons 0.984 Long tons
Ounces Pounds Short tons Long tons
28.4 Grams 0.454 Kilograms 0.907 Metric tons 1.016 Metric tons
FM 5-428 Appendix B
Appendix B
Method of Making Slump
B-1. This test method covers the procedures to use both in the laboratory and in the field to determine the consistency of the concrete. Although not a precise method, it gives sufficiently accurate results. The slump test does not apply if the concrete contains aggregates much larger than 2 inches in size.
B-2. The following apparatus are available in the mobile laboratory: a metal mold and a tamping rod. Metal Mold B-3. The metal mold is a piece of 16-gage galvanized sheet metal shaped like a 12-inch high truncated (cut off) cone having an 8-inch diameter base and a 4-inch diameter top (see Figure B-1). Both the base and top are open, parallel to each other, and perpendicular to the axis of the cone.
FM 5-428 Appendix B
Figure B-1. Measuring slump TAMPING ROD B-4. The tamping rod is 5/8 inch in diameter, 24 inches long, and has a 1-inch taper at one end terminating in a rounded tip bullet nose. It have a radius of about 1/4 inch.
B-5. The concrete samples that make up the test specimens must be representative of an entire batch. Note for future reference the work location of the concrete batch sampled. Take all concrete samples at the mixer, or if you are using ready-mixed concrete, during discharge from the transportation vehicle. Start taking these samples by repeatedly passing a scoop or pail through the concrete stream at the beginning of discharge, and continuing until the entire batch discharges. Take a sample of paving concrete immediately after depositing the batch on the subsurface. Collect at least five samples from different portions of the pile and thoroughly mix them to form the test specimen. Transport the specimens to the testing site to counteract segregation. Mix the concrete using a shovel until it is uniform in appearance.
B-6. Dampen the mold and place it on a flat, moist, nonabsorbent, and firm surface. Fill the mold immediately with three equal layers of a concrete specimen described in paragraph B-5. As you fill the mold, rotate each scoopful of the concrete around the top edge of the
FM 5-428 Appendix B
mold as the concrete slides from it. This ensures a symmetrical concrete distribution within the mold. Tamp each layer 25 strokes with the tamping rod, distributing the strokes uniformly over the cross section of the mold, and penetrating the underlying layer. Tamp the bottom layer throughout its depth. After tamping the top layer, strike off the surface with a trowel so that the concrete fills the mold exactly. Without any delay, carefully lift the mold straight up from the concrete and place it beside the specimen.
B-7. Place the tamping rod across the top of the mold. Measure the distance between the bottom of the rod and the displaced original center of the specimen's top surface. If a shearing off of concrete from one side or portion of the mass occurs, disregard the test and make a new test on another portion of the sample. NOTE: If two consecutive tests on a sample of concrete show a falling away or shearing off of a portion of the concrete from the mass of the specimen, the concrete probably lacks the necessary plasticity and cohesiveness for the slump test to be applicable.
B-8. After completing the slump measurement, tap the side of the specimen gently with the tamping rod. How the concrete mix behaves under this treatment is a valuable indication of its cohesiveness, workability, and placement. A well-proportioned, workable mix will gradually slump (fall or flatten out) but still retain its original consistency, whereas a poor mix will crumble, segregate, and fall apart.
The sand will clings together without excess water being forced out (see Figure C-2). The sand will have moisture on it and may even drip (see Figure C-3 below). C-2. The procedure allows for some variation in estimating. therefore. This moisture should be accounted for by decreasing the amount of water added to the dry materials in order to maintain the W/C ratio that is a part of the concrete design. Very wet sand (5% TO 8% FSM). This negates the effect of evaporation at the surface of the pile. The samples used for this test should be taken from a depth of 6 to 8 inches below the surface of the piled sand. open the hand and observe the sample.FM 5-428 Appendix C Appendix C Field Test for Moisture Deformation on Sand C-1. the percentage of moisture determined is somewhat judgmental. q Wet sand (3% TO 4% FSM). Then. The sand will fall apart. The amount of FSM can be estimated from the following criteria: q Damp sand (O% TO 2% FSM). Damp sand C-1 . Sands used as the fine aggregate in concrete may contribute a significant amount of moisture to the concrete mix. The damper the sand the more it tends to cling together (see Figure C-1). The following procedure can be used as a field test for estimating the amount of moisture in sand. Squeeze a sample of sand in the hand. The sand ball will glisten or sparkle with water. q Figure C-1.
Very wet sand C-3. Use these estimates to adjust the mix design as indicated in Paragraph 3-17 and 3-18. The percentage of FSM determined by this method approximates the amount of water by weight on the sand.FM 5-428 Appendix C Figure C-2. C-2 . Wet sand Figure C-3.
FM 5-428 Glossary GLOSSARY ACRONYMS AND ABBREVIATIONS AASHTO American Association of State Highway and Transportation Officials ACI ASTM ATTN BB BF CA CESL CMC CL cu ft cu yd D DA DC DL DRUW EM ESL F f'c Glossary-1 American Concrete Institute American Society for Testing and Materials attention bean bolster bulking factor coarse aggregate(s) corrected equivalent static load continuous high chair critical load cubic foot cubic yard (s) depth Department of Army District of Columbia dead load dry-rodded unit weight enlisted men equivalent static load fahrenheit specified compressive strength of concrete. psi .
inches a constant.FM 5-428 Glossary f't FA FM FSM ft gal gm HC HP HQ hr inch K kg lb lb/cu ft lb/cu yd LF lin liq LL m max MCP min mm MPa flexural tensile stress fine aggregate(s) field manual free surface moisture foot gallon(s) gram(s) high chair horsepower headquarters hour(s) inch. usually between 8-10 kilogram(s) pound(s) pounds per cubic foot pounds per cubic yard linear foot linear liquid live load meter maximum maximum concrete pressure minimum millimeter megapascal Glossary-2 .
in psi surfaced on four sizes slab bolster specific gravity static load square saturated. surface dry total load technical manual table of organization and equipment TRADOC United States Army Training and Doctrine Command ULJ ULS ULSstr ULW uniform load on the joist uniform load on a stud uniform load on the stringer uniform load on wale Glossary-3 .FM 5-428 Glossary MO MOS MSA MSS MWS NCO Nos OC pH ppm psi PV R S4S SB SG SL sq SSD TL TM TOE Missouri military occupational specialty maximum-size aggregate maximum stud spacing maximum wale spacing noncommissioned officer numbers on center denotes hydrogen-ion activity parts per million pounds per square inch partial volume flexural strength.
FM 5-428 Glossary US USAES vol w W/C wt yd United States United States Army Engineer School volume width water to cement weight yard(s) SYMBOLS delta. an angular measurement. degrees < > less than. or equal to perpendicular to || ' " @ % + db parallel to feet inches approximately or at percent plus or minus diameter of bar Glossary-4 . or equal to greater than. change in x degrees : to (ratio) diameter theta.
September 1981. Trailer Mounted: Gasoline Driven. Model 8CM-24/F. FM 5-426. References-1 . TM 5-3895-221-15. 21 February 1966. 27 October 1995. Planning and Design of Roads. TM 5-3895-372-10. Building Codes Requirements for Reinforced Concrete. Route Reconnaissance and Classification.1-81. 5 October 1979. 10 June 1985. 26 August 1994. Volume D-1 Asphalt and Concrete Equipment. TM 5-331D. 3 October 1995. 5 May 1998. Survivability. ACI 306. Organizational. 1996. and Depot Maintenance Manual: Mixer. Maintenance and Repairs of Surface Area. 29 September 1994. Deformed and Plain Billet Steel Bars for Concrete Reinforcement. Carpentry. Army Publications FM 5-103. ASTM A615. 1 April 1960.R-78. FM 5-170. FM 5-430-00-2. TM 5-349. 19 February 1962. General Support. 30 August 1962. FM 5-430-00-1. Guide for using Admixture in concrete. Volume II. Planning and Design of Roads. TM 5-337. 1978. Paving and Surfacing Operations.FM 5-428 References REFERENCES SOURCES USED These are the sources quoted or paraphrased in this publication. Utilization of Engineer Construction Equipment. Cold Weather Concreting. Volume I. 1983. Arctic Construction. Concrete. M919. Direct Support. Operator. Airfields and Heliports in the Theater of Operations Road Design. Operation Instructions for Concrete-Mobile Mixer Body. 16 cubic feet (Chain Belt Model HBG). Airfields and Heliports in the Theater of Operations -Airfield and Heliport Design. Nonmilitary Publication ACI 211. TM 5-624. ACI 318-83.
Department of Army (DA) Form 2028. Lightweight Pieces in Aggregate. 1985. 1997. 1996. Sulfur in Graphite by Combustion-Iodometric Titration Method. Air-Entraining Admixture for Concrete. Portland Cement. Concrete Aggregates. Engineer Data. ASTM C260. ASTM C123.FM 5-428 References ASTM A616. 1992. ASTM C87. Rail Steel Deformed and Plain Bars for Concrete Reinforcement. 1996. Effect of Organic Impurities in Fine Aggregates on Strength of Mortar. ASTM C40. ASTM A617. 1983. Bulk Density "Unit Weight" and Voids in Aggregate. 1995. ASTM C33. ASTM C117. ASTM C29. Recommended changes to Publications and Blank Forms. 1995. Axle-Steel Deformed and Plain Bar for Concrete Reinforcement. ASTM C150. 1997. Material Finer Than 75 (number 200) Sieve in Mineral Aggregate by Washing. DOCUMENTS NEEDED These documents must be available to the intended users of this publication. ASTM C816. References-2 . February 1974. FM 5-34. READINGS RECOMMENDED This reading contain relevant supplemental information. 1997. Organic Impurities in Fine Aggregates for Concrete. 14 September 1987. 1997.
FM 5-428 Authorization Authorization .
FM 5-428 Authorization Authorization-2 .
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