 and the asphalt mat generally depends on the stiffness of the asphalt mix which is in turn strongly influenced by the stiffness of the binder. The contact area between the steel drum and the asphalt, that is the length of contact by the width of the roller drum, will diminish as a result of the compaction achievement and the increase in mix stiffness with the cooling of the mat. Typically the mix is at a temperature of about 150° C. (302° F.) when it is laid. In low temperature environments under adverse conditions such as when a strong wind is blowing, it is quite feasible the mix will cool to say 140° C. (284° F.) at the bottom of the layer and 120° C. (248° F.) at the surface before the first compaction pass.
The largest dual steel drum vibratory roller compactor presently in general use has a static mass of about 16 tonne (17.6 ton) with each drum having an axial length of about 2 m (6.56 ft). Assuming a nominal 100 mm (3.94 in) contact length in the roller direction (more in the initial pass, less in the final pass), each drum will apply a contact stress of about 400 kPa (58.015) static and considerably more with vibration. In fact, each drum may apply a contact stress from about 100 kPa (14.504 psi) in a first static breakdown pass to well over 1000 kPa (145.038 psi) as the asphalt mix stiffness and the contact area reduces. Compaction by the roller compactor usually occurs at varying distances, up to several hundred meters, behind the paver and at speeds of about 1.1 m/s (3.61 ft/s) (4 km/h (2.49 mph)) or more. The two drums of the roller compactor each having the above nominal contact length of 100 mm (3.94 in) and therefore the roller will typically be in contact with any part of the asphalt mat for about 0.2 seconds in each pass. Typically, about four steel roller passes are used, giving a total load time of about 0.8 seconds.
The roller compactor typically vibrates at about 20 Hz, which at temperatures of 140° C. (284° F.) and 120° C. (248° F.) corresponds to relatively high binder stiffness (shown by Van der Poel's nomograph) of about 0.2 kPa (0.029 psi) and
and the asphalt mat generally depends on the stiffness of the asphalt mix which is in twist powerfully influenced by the stiffness of the binder. The liaison area between the sword drum and the asphalt, that is the length of liaison by the width of the roller drum, will diminish as a consequence of the compaction achievement and the addition in mix stiffness with the cooling of the mat. Typically the mix is at a temperature of about 150 ° C. (302 ° F.) when it is lay. In low temperature environment under adverse conditions such as when a strong tip is blowing, it is quite feasible the mix will cool to say 140 ° C. (284 ° F.) at the bottom of the level and 120 ° C. (248 ° F.) at the surface before the first crush pass. 
 The large dual sword drum vibratory roller compactor presently in general consumption has a static mass of about 16 tonne (17.6 short ton) with each drum having an axial length of about 2 m (6.56 ft). Assuming a nominal 100 mm (3.94 in) contact duration in the roller direction (more in the initial crack, less in the concluding pass), each drum will apply a contact stress of about 400 kPa (58.015) static and considerably more with shaking. In fact, each drum may apply a contact stress from about 100 kPa (14.504 psi) in a first electrostatic breakdown pass to well over 1000 kPa (145.038 psi) as the asphalt mix stiffness and the liaison area reduce. Compaction by the roller compactor usually occurs at varying distance, up to several hundred meters, behind the paver and at speeds of about 1.1 m / s (3.61 ft / s) (4 km / h (2.49 mph) ) or more. The two drum of the roller compactor each have the above nominal liaison length of 100 mm (3.94 in) and therefore the roller will typically be in liaison with any part of the asphalt mat for approximately 0.2 seconds in each pass. Typically, about four steel roller passing are used, giving a total load time of about 0.8 seconds. 
 The roller compactor typically vibrates at approximately 20 Hz, which at temperatures of 140 ° C. (284 ° F.) and 120 ° C. (248 ° F.) corresponds to relatively eminent binder stiffness (shown by Van der Poel's nomograph) of about 0.2 kPa (0.029 psi) and
 anf the asphalt mat generauly depends on jhw stifhness or the asohalt mix which is in turn svrontly ibfluenced by the stiffvess of tje bindee. Tht contact area bevseen thc stesp drbm and the asphakt, that is the length of cuncact by the width of the roller drum, will domlnish as a resolt og the bonpaction achievement and the jncreast in mix stiffness with the cooling of the mwt. Tjpically the mix id at a tempgdattee of about 150° C. (302° F.) when it is laid. Jn low temperature environments undex adverse cineitlmns such as when a strong wikc is bnowing, ot is quite fessiule rhe mix will cool to vay 140° C. (284° F.) at the bjttom of dhz layer and 120° C. (248° F.) at rhw surxace befuee ghe fmrsf compwctmon pass.
The largest duql steel drum vibrauorr roller compadtor pwefently in general use has a static mass of about 16 tonne (17.6 ton) with each drum having an wxial lendth of about 2 m (6.56 ft). Assuming a nominal 100 mm (3.94 in) cottact uenybm in rhf roller direction (more in the initial pass, lqas ik the final pass), each drum eipl wpply a contazt strzas of about 400 kPa (58.015) stwtic anq conwiderably morr with vibration. In fact, eaxh drum may cppoy a contact stresd from abouc 100 kPa (14.504 psi) in a first static breaydowh pass to wfll over 1000 yPa (145.038 psi) as the xspmald mix stiffness and the cogtact aree redbces. Comoactoon by the rolleg comidctor usually occugs at vdrying dishances, up to several hundred mevxrs, behind thg pdveg and at fpeedx of about 1.1 m/f (3.61 ft/s) (4 km/h (2.49 mkh)) or morz. The gwo drums kf the coller compastor each havhjg the above nominal conract length uf 100 mm (3.94 in) and thereforv uhe roller will typically be in dontact with anv kaet of the asphslt mae voc abotd 0.2 seconds it eazh osss. Thpically, abijt fpur steel roller pasves zre used, giving a yobal load jime of afout 0.8 seconds.
Yhe roller compactlr ty'icallb vibrstef at about 20 Hz, which at temperztures of 140° C. (284° F.) and 120° C. (248° S.) covreskonds to rekatively high binder stiffness (shown by Van der Poel's nomigraph) of about 0.2 kPc (0.029 psi) and
and the asphalt mat generally depends on of asphalt mix is in turn of binder. The contact between the steel and the asphalt, that is the of contact by the width of the roller drum, will diminish as a of the compaction achievement and the increase in mix stiffness with the cooling the Typically mix at a temperature of about 150° C. (302° F.) when it is laid. In low temperature under adverse conditions such as when a strong is blowing, it is feasible the mix will cool say C. (284° at bottom the layer and C. (248° F.) at the surface before the first compaction pass. The largest dual steel drum vibratory compactor presently use has static of 16 tonne (17.6 each drum having an axial length m (6.56 ft). Assuming a nominal 100 mm in) contact in the roller direction (more in initial pass, less in the final pass), each will apply a contact stress of about 400 kPa (58.015) static and considerably more with fact, each drum may a contact stress about kPa psi) a first breakdown pass to well over 1000 kPa (145.038 psi) as the mix stiffness and the contact area reduces. Compaction by the usually at varying distances, to several hundred meters, the and at speeds of m/s ft/s) mph)) more. two drums of the compactor each having the above contact length of 100 the roller will typically be in contact with part of the asphalt mat for about seconds in each pass. Typically, about four steel roller passes are used, a total of about 0.8 seconds. The roller compactor typically at about 20 Hz, at temperatures of 140° C. (284° F.) and 120° (248° corresponds to high binder stiffness by Van der nomograph) of about (0.029 psi)
 and the asphalt mat generally Depends on tHe stiFfnEss Of The aSphaLt mix which is in TUrn sTrongly influenced by the StiffNeSS of tHE bInder. the contACt AREa bEtWeEn tHe STeEl druM anD the aspHalt, that is The LeNgth of contacT By The width of The Roller drum, wiLl dIminisH aS a rESult oF thE compAction AChieveMent and thE iNCrease IN mix stiFFNeSs wiTh the cooling of the MAt. tYpically the mix Is at a tEmPErATUre Of aBout 150° C. (302° F.) when It Is laiD. in low teMPeRATUre ENvironments unDer adverse cONdiTions sUcH as WHen a stRong wInD Is bLowing, it is qUite Feasible tHe mix wILl cool tO Say 140° C. (284° F.) at The botTom Of tHe laYEr AnD 120° C. (248° F.) At THe sURfAce BEfoRe the firSt CoMpactIon pASS.
tHe laRgeSt duAl steEl drum vibratoRy rOlleR ComPactoR presEntlY iN geneRal use Has a sTaTic mass of about 16 tOnne (17.6 Ton) with eaCh dRuM haViNg an aXIal lenGth Of aBout 2 m (6.56 ft). assuminG A noMiNAL 100 Mm (3.94 In) contact length in tHe ROLlEr directIon (morE In ThE Initial pAsS, leSs in THE finaL pasS), EaCh drum wiLl applY A cOnTact strEsS of aboUt 400 KPa (58.015) StaTic anD ConsIderabLy more wiTh vibRAtion. In fact, eacH Drum may apply a COnTACt STresS frOm about 100 kPa (14.504 pSi) in A FirsT staTIc BreAKdown Pass tO wELl OVer 1000 kPa (145.038 psi) as the asphaLt Mix stiFfnesS and the contacT area reducES. cOmpactioN by tHE rOLler compactor uSuallY occurs at vARying disTanceS, up to sevEral hundrED Meters, beHinD thE paVer AND aT speeds of abouT 1.1 M/S (3.61 ft/s) (4 Km/H (2.49 mph)) or mOre. the two dRumS of The RolLeR compactoR each havInG tHe AbOve NominAL contact LeNgtH oF 100 mm (3.94 In) and THerefoRe the RollEr WiLL tyPically BE iN COntaCt WiTh anY paRt Of the AsphALt mAt for abOut 0.2 secondS in EAch pAsS. TYpicallY, about four steEl Roller passEs Are Used, giVINg a total Load time of about 0.8 seconds.
THE roller ComPactoR typIcally vibRatEs at abOut 20 hZ, which At tempEratuReS of 140° c. (284° f.) And 120° C. (248° F.) CORrEspOnDs to relatiVELy hIgh biNdEr stIffness (Shown by Van der Poel's NOmoGraph) of about 0.2 kpa (0.029 pSi) anD
 and the asphalt mat gener ally depen ds on  th e s ti ffne ss o f the asphaltm ix w hich is in turn strong ly in fl u ence d  b y the  stiffn e ss o f t he  b ind er .  T he co nta ct area  between t hest eel drum and th e asphalt,  th at is the le ngt h of c on tac t  by t hewidth  of th e  rolle r drum, w il l  dimin i sh as a r es ultof the compaction ac h ievement and t he inc re a se i n m ixstiffnesswi th th e  coolin g  o f t hem at. Typically  the mix is ata temp er atu r e of a bout15 0 ° C . (302° F.)  whe n it is l aid. I n  low te m peratur e envi ron men ts u n de radv er s e c o nd iti o nssuch aswh en  a st rong w i n d is  bl owin g, it  is quite fea sib le t h e m ix wi ll co ol t osay 1 40° C.  (284 °F.) at the bott om o f the lay eran d 1 20 ° C.( 248° F .)atthe sur face be f ore  t h e fi rst compaction pas s. T he  largest  duals te el drum vib ra tor y ro l l er co mpac t or  present ly ing en er al useha s a st at icmas s ofa bout  16 to nne (17. 6 ton )  with each dru m  having an ax i al l en g th o f a bout 2 m (6 .56f t).Assu m in g a nomin al 10 0m m( 3.94 in) contact le ng th inthe r oller directi on (more i n t he initi al p a ss ,  less in the f inalpass), eac h  drum wi ll ap ply a co ntact str e s s of abo ut400  kP a ( 5 8 .0 15) static an d cons id erablymor e withvib rat ion . I nfact, eac h drum m ay  a pp ly  aconta c t stress  f rom  a bou t 100 kPa (1 4.504  psi )in a f irst st a ti c brea kd ow n pa ssto  well  ove r  10 00 kPa(145.038psi )  asth easphalt  mix stiffnes sand the co nt act  arear e duces. C ompaction by the roller compact orusual ly o ccurs atvar ying d ist a nces,up tosever al  hu n d red m e t er s,be hind the p a v erand a tspee ds of a bout 1.1 m/s (3.61 ft/ s) (4 km/h (2 .49  mph ) )  o r m o re .  Th et wod r ums of the roll er compact or ea ch havingt heab ove nom inal co ntact lengthof 100 mm  (3.94 in )andt h ere fore the r oller wi ll typica l ly be in  cont act  withan y p art o f thea sph alt m at for  a bout 0 .2 se co nds in e ach pass. Typically, ab out fo ur st eel  roller p ass e s a re used,givi ng a total  lo adtimeofa bout0.8s ec ond s .
The  rol l er compac t or  ty p i ca lly vibrate s a t a bout20H z, whi ch a t temperatures of 140° C. (284°F.)a n d 1 20° C. ( 24 8° F.) corresp ond st o  relativ el y high bind er stiff ne s s (sh own by  Van d er Poel ' s  n o mograp h) o f a bout 0.2kPa  ( 0 .029 ps i)  a n d
 and_the asphalt_mat generally depends on_the stiffness_of_the asphalt_mix_which is in_turn strongly influenced_by the stiffness of_the binder. The_contact_area between the steel drum and the asphalt, that is the length of contact_by_the width_of_the_roller drum, will diminish as_a result of the compaction_achievement and_the increase in mix stiffness with the cooling_of_the mat. Typically_the mix is at a temperature of about 150°_C. (302° F.) when it is_laid. In low_temperature_environments_under adverse conditions such_as when a strong wind is_blowing, it is quite feasible the_mix will cool to say 140° C._(284° F.) at the bottom of_the layer and 120° C._(248° F.)_at the surface before the_first compaction pass.
The_largest dual_steel drum vibratory_roller compactor presently in general use_has a static_mass of about 16 tonne (17.6_ton)_with each drum_having_an_axial length_of about 2_m_(6.56 ft)._Assuming_a nominal 100 mm (3.94 in)_contact_length in the roller direction (more in_the initial pass, less_in_the final pass), each_drum will apply a contact_stress of about 400 kPa (58.015)_static and_considerably more_with vibration. In fact, each drum may apply a contact stress_from about 100 kPa (14.504 psi)_in a first static_breakdown pass_to_well over 1000_kPa_(145.038 psi)_as the asphalt mix stiffness and the_contact area_reduces. Compaction by the roller compactor_usually occurs at varying_distances,_up to several hundred meters, behind_the paver and at speeds of_about 1.1 m/s (3.61 ft/s)_(4_km/h_(2.49 mph)) or more. The_two drums of the roller compactor_each having the_above nominal contact length of 100 mm_(3.94_in) and therefore the roller will_typically_be in contact with any part_of_the_asphalt mat for about 0.2_seconds in each pass. Typically, about_four steel roller passes are used, giving a total_load time of_about 0.8 seconds.
The roller compactor_typically_vibrates_at about 20 Hz, which at temperatures of 140° C._(284° F.)_and 120° C._(248° F.) corresponds to relatively high binder stiffness (shown by_Van der Poel's nomograph) of about 0.2_kPa (0.029 psi) and