道路施工设备英文材料.docx
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道路施工设备英文材料.docx
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道路施工设备英文材料
PavingEquipment
Stabilizers/Reclaimers
Astabilizer/reclaimerisavehiclewithadualpurpose.Thesemachineshavealargerotorbladewhichmaybeusedtocutandpulverizedamagedoroldpavement,butwhichalsomaybeusedtomixlime,flyash,orcementintothesubbaseinordertostabilizepoorsoils.
MillingMachines
Atoplayerismilledofftheexistingpavementtoprovidearelativelysmoothsurfaceonwhichtopave.Millingisalsocommonlyusedtoremoveadistressedsurfacelayerfromanexistingpavement.MillingmachinesaretheprimarymethodforremovingoldHMApavementsurfacematerialpriortooverlay.Theycanbefittedwithautomaticgradecontroltorestorebothlongitudinalandtransversegradeandcanremovemostexistingpavementdistortions.Millingalsoproducesarough,groovedsurface,whichwillincreasetheexistingpavement’ssurfaceareawhencomparedtoanungroovedsurface.Thesurfaceareaincreaseisdependentonthetype,number,conditionandspacingofcuttingdrumteethbutistypicallyintherangeof20to30percent,whichrequiresacorrespondingincreaseintackcoat(20to30percentmore)whencomparedtoanunmilledsurface.Millingisadvantageousbecauseit:
∙ProvidesRAPforrecyclingoperations.
∙Efficientlyremovesdeterioratedpavementthatisunsuitableforretentionintheoverlaidpavement.
∙Providesahighlyskidresistantsurfacesuitablefortemporaryusebytrafficuntilthefinalsurfacecanbeplaced.
∙AllowscurbandgutterlinestobemaintainedorreestablishedbeforeHMAoverlays.
∙Providesanefficientremovaltechniqueformaterialnearoverheadstructuresinordertomaintainclearancesforbridgestructures,trafficsignalsandoverheadutilities.
Figure1:
Sideviewofmillingmachine.
Figure2:
Cuttingtipsonrotarydrum.
Graders
Gradersmaybeusedinplaceofmillingmachinesifthebasecourseisdirtorgravel.Theyarevehicleswithlargebladesthatcreateawideflatsurfaceforasphalttobeplacedon.
Figure3:
AgraderpreparingthesubgradeonaprojectonSR528inMarysville,WA.
Sweepers
Sweeperscleanthesurfaceoftheroadafterithasbeenmilledorgraded.Thisisnecessarybecauseexcessivedustanddebrisonthegroundcanpreventproperbondingbetweentheasphaltandthebasecourse.Largepiecesofdebriscanalsocausenon-uniformcompactionoftheasphalt.
Figure4:
Sweepingmachine.
BatchPlant
Batchplants,whichproduceHMAinindividualbatches,aretheolderofthetwotypesofHMAproductionfacilities;itwasnotuntilthe1970sthatdrumplantsbecameapopularHMAproductionoption.Typicalbatchquantitiesrangefrom1.5to5tonsofHMAandeachbatchcantake15–45secondstomake.
Figure5:
Batchplant
DrumPlant
Drumplants,whichproduceHMAinacontinuousmanner,generallyofferhigherproductionratesthanbatchplantsforcomparablecost.Typicalproductionratesfordrumplantsvarybetweenabout100tons/hruptoover900tons/hrdependingupondrumdesign.
Figure6:
Acontinuousordrumplant.
DumpTrucks
Dumptrucksmovethehotasphaltfromtheplanttothejobsite.Therearemanykindsofdumptrucks:
∙Enddump:
unloadtheirpayloadbyraisingthefrontendandlettingthepayloadslidedownthebottomofthebedandoutthebackthroughatailgate.Theyarethemostpopulartransportvehicletypebecausetheyareplentiful,maneuverableandversatile.
∙Bottomorbellydump:
Bottomdumptrucksunloadtheirpayloadbyopeninggatesonthebottomofthebed.Internalbedwallsareslopedtodirecttheentirepayloadoutthroughtheopenedgates.Dischargeratescanbecontrolledbythedegreeofgateopeningandthedischargeisusuallyplacedinanelongatedpile,calledawindrow,infrontofthepaverbydrivingthetruckforwardduringdischarge.WindrowsrequireaspecialMTV(materialtransfervehicle)tofeedtheHMAintothepaver.
∙Livebottomorflo-boy:
Livebottomdumptruckshaveaconveyorsystematthebottomoftheirbedtounloadtheirpayload.HMAisdischargedoutthebackofthebedwithoutraisingthebed.Livebottomtrucksaremoreexpensivetouseandmaintainbecauseoftheconveyorsystembuttheyalsocanreducesegregationproblemsandcaneliminatesomedetrimentaltypesoftruckbed–pavercontact(becausethebedisnotraisedduringdischarge).
Figure7:
EnddumptruckplacingWMAintoaskip.
MaterialTransferVehicles
Materialtransfervehicles(MTVs)areusedtoassistthepaverinacceptingHMA.MostpaversareequippedtoreceiveHMAdirectlyfromenddumporlivebottomtrucks,howeverincertainsituationsitcanbenecessaryoradvantageoustouseanMTV.PavingusingbottomdumptrucksandwindrowsrequiresawindrowelevatorMTV,whileotherMTVsareusedtoprovideadditionalsurgevolume,whichisadvantageousbecauseitallowsthepavertooperatecontinuouslywithoutstopping,minimizestruckwaitingtimeatthepavingsiteandmayminimizeaggregatesegregationandtemperaturedifferentials.
Figure8:
Materialtransfervehicle,orshuttlebuggy.
AsphaltPavers
Theasphaltpaverisaself-propelledformlesslaydownmachinewithafloatingscreed.HMAisloadedinthefront,carriedtotherearbyasetofflightfeeders(conveyorbelts),spreadoutbyasetofaugers,thenleveledandcompactedbyascreed.Thissetoffunctionscanbedividedintotwomainsystems:
∙Tractor:
Thetractorcontainsthematerialfeedsystem,whichacceptstheHMAatthefrontofthepaver,movesittotherearandspreadsitouttothedesiredwidthinpreparationforscreedlevelingandcompaction.
∙Screed:
Themostcriticalfeatureofthepaveristheself-levelingscreedunit,whichdeterminestheprofileoftheHMAbeingplaced(Robertsetal.,1996[1]).ThescreedtakestheheadofHMAfromthematerialdeliverysystem,strikesitoffatthecorrectthicknessandprovidesinitialmatcompaction.Figure5showsscreedcomponentsandthesixbasicforcesthatactuponthescreedtodetermineitsheightand,thus,pavementthickness.
Thescreedhelpscontroltheamountofmaterialextrudedontothebasecourse,flatteningtheasphaltontheground.Italsoassistsinofferingalevelsurfaceforcompactionregardlessoftheconditionofthebasecourse.However,thebasecourseneedstobereasonablylevelinordertopreventfuturecracking.
Figure9:
Atypicalasphaltpavingmachine.
Compactors/Rollers
TherearethreebasicpiecesofequipmentavailableforHMAcompaction:
(1)thepaverscreed,
(2)thesteelwheeledrollerand(3)thepneumatictireroller.EachpieceofequipmentcompactstheHMAbytwoprincipalmeans:
1.ByapplyingitsweighttotheHMAsurfaceandcompressingthematerialunderneaththegroundcontactarea.Sincethiscompressionwillbegreaterforlongerperiodsofcontact,lowerequipmentspeedswillproducemorecompression.Obviously,higherequipmentweightwillalsoincreasecompression.
2.Bycreatingashearstressbetweenthecompressedmaterialunderneaththegroundcontactareaandtheadjacentuncompressedmaterial.Whencombinedwithequipmentspeed,thisproducesashearrate.Loweringequipmentspeedcandecreasetheshearrate,whichincreasestheshearingstress.Highershearingstressesaremorecapableofrearrangingaggregateintomoredenseconfigurations.
ThesetwomeansareofcompactingHMAareoftenreferredtocollectivelyas“compactiveeffort”.
PaverScreed
Approximately75to85percentoftheoreticalmaximumdensity,orRicedensity,willbeobtainedwhenthemixpassesoutfromunderthescreed.
SteelWheelRollers
Steelwheelrollersareself-propelledcompactiondevicesthatusesteeldrumstocompresstheunderlyingHMA.Theycanhaveone,twooreventhreedrums,althoughtandem(2drum)rollersaremostoftenused.Thedrumscanbeeitherstaticorvibratoryandusuallyrangefrom35to85inchesinwidthand20to60inchesindiameter.Rollerweightistypicallybetween1and20tons.
Somesteelwheelrollersareequippedwithvibratorydrums.Drumvibrationaddsadynamicloadtothestaticrollerweighttocreateagreatertotalcompactiveeffort.Drumvibrationalsoreducesfrictionandaggregateinterlockduringcompaction,whichallowsaggregateparticlestomoveintofinalpositionsthatproducegreaterfrictionandinterlockthancouldbeachievedwithoutvibration.Asageneralrule-of-thumb,acombinationofspeedandfrequencythatresultsin10–12impactsperfootisgood.At3000vibrations/minutethisresultsinaspeedof2.8–3.4mph.
Figure10:
Asteelwheelroller
PneumaticTireRollers
Pneumatictirerollersareself-propelledcompactiondevicesthatusespneumatictirestocompacttheunderlyingHMA.Pneumatictirerollersemployasetofsmooth(notread)tiresoneachaxle;typicallyfourorfiveononeaxleandfiveorsixontheother.Thetiresonthefrontaxlearealignedwiththegapsbetweentiresontherearaxeltogivecompleteanduniformcompactioncoverageoverthewidthoftheroller.Compactiveeffortiscontrolledbyvaryingtirepressure,whichistypicallysetbetween60and120psi.Inadditiontoastaticcompressiveforce,pneumatictirerollersalsodevelopakneadingactionbetweenthetiresthattendstorealignaggregatewithintheHMA.Becauseasphaltbindertendstostickmoretocoldtiresthanhottires,thetireareaisofteninsulatedwithrubbermattingorplywoodtomaintainthetiresnearmattemperaturewhilerolling.
Figure11:
Apneumatictirerollercompactingchipseal.
References
∙WashingtonAsphaltPavementGuide,WashingtonAsphaltPavementAssociation,Inc.,2002
Footnotes (↵returnstotext)
1.Roberts,F.L.,Kandhal,P.S.,Brown,E.R.,Lee,D.Y.,andKennedy,T.W. (1996). HotMixAsphaltMaterials,MixtureDesign,an
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