JTG D50-2017(EN) 公路瀝青路面設計規(guī)范 英文版

JTGIndustryStandardsofthePeople’sRepublicofChinaSpecificationsforDesignofHighwayAsphaltPavementIssuedbyMinistryofTransportofthePeople’sRepublicofChinaIndustryStandardsofthePeople’sRepublicofChinaSpecificationsforDesignofHighwayAsphaltPavementEditingorganizationinchargeofChineseversion:CCCCRoadandBridgeConsultantEditingorganizationinchargeofEnglishversion:ChinaRoadandBridgeCorporaIssuingAuthority:MinistryofTransportofthePeople’sRepublicofChina英文版編譯出版說明協(xié)調、綠色、開放、共享的共同發(fā)展。在絲綢之路經濟帶與21世紀球交通運輸發(fā)展的需求，增進世界連接，促進知識傳播與經驗分享，中華人民共和國交通運輸部組織編譯并發(fā)布了一系列中國公路行業(yè)系范圍涵蓋公路工程從規(guī)劃建設到養(yǎng)護和運營管理全過程所需要的（JTJ01-81）基礎上，開始制訂公路路線、路基、路面、橋梁、涵的經濟發(fā)展存在一定差距，造成交通量差異較大。不同的自然條件、的編譯發(fā)布便是希望將中國的工程經驗和技術成果與各國同行進行交流分享，為其他國家類似地形地質條件的公本英文版的編譯工作由中華人民共和國交通運輸部委托中國路橋工（地址：北京市東城區(qū)安定門外大街丙88號中路大廈，郵政編碼：英文版主編單位：中國路橋工程有限責任公司英文版主編：姚海冬，盧山英文版參編人員：張慧彧，曾峰，張慶紅英文版主審：艾列克斯維瑟教授（南非）ThePeople’sRepublicofChinaMinistryofTransportPublicNoticeNo.10PublicNoticeonIssuingtheDesignSpecificationsforHighwayAsphaltPavementHerebytheSpecificationsforDesignofHighwayAsphaltPavement(JTG/TD50-2017)isissuedasoneoftheIndustryStandardsforHighwayEngineering,andshallbecomeeffectiveonSeptember1,2017.TheformereditionoftheSpecificationsforDesignofHighwayAsphaltPavement(JTGD50-2006)shallbesupersededfromthesamedate.ThiseditionoftheSpecificationforDesignofHighwayAsphaltPavementwasdraftedandcompiledbyCCCCRoadandBridgeConsultantsCo.,Ltd.ThegeneraladminfinalinterpretationoftheStandardshallbelongtoMinistryofTranspointerpretationforapplicationandroutineadministrationofthisStandardshallbeprovidedbytheCCCCRoadandBridgeConsultantsCo.,LRoadandBridgeConsultantsCo.,Ltd.(88DAndinBeijing,PostalCode:100011).ThefeedbackMinistryofTransportofthePeople'sRepublicofChinaGeneralOfficeofMinistryofTransportPrintedonMarch22,2017—7—ForewordStandardsreflecttheachievementofccommunications,andimproveglobalconnectivitMinistryofTransportofthePeople’sRepublicofChinaorganizedtranslationandpublishedaninternationalversionofthetransportation,achieveinterconnecteddevelopmentandpromoteknowledgedispersionJTGisthedesignationreferringtothestandardsandspecificationsofthehightransportationindustry,issuedbytheMinistryofTransportofthePeople’sRepublicofChina.Itcoversthestservicefortheprocessfromhighwayplanningthroughtcriteriaforsafety,environm8———Transportationplaysapioneeringrolandindustrystandardsforhighwayinfrastructurehavecontinuouslyupdatedandimproved.Intheearly1980’s,theEngineering(JTJ01-81)wasformulated,followedbyaseriesoftechnicalspecificationscoveringhighwayplanning,geometry,earthworks,pavementsandstructuralwork.TheSpecificationstheDesignofHighwayFlexiblePavement(JTJ014-86)waspublishedandimplementedin1986,andthenrenamedasSpecificationsforDesignofHighwayAsphaltPavement(JTJ014-97)initsfirstrevisionin1997.Thesecondrevision(JTGD20-2006)wasconductedin2systemforthedesignofhighwayasphaltpavementhasbeenfullyestablishedbasedon40-yearsoftechnicaldevelopment.Thethirdrevision(JTGD20-2017)wasissuedinSeptember2018andTheterritoryofChinaisex4000metersfromtheTibetPlateauinthewesttocoastalplainintheeast.TheecodevelopmentlevelinChina,andthushighwaytrafficvolumes,arealsodiffecountry.Thevarietyinenvironment,typesofvehiclesandvehdifferentpavementdesignandmaterialselection.Becauseofthehighcontributionofpavementcostinroadconstruction,economicconsiderationsarealwaystakenin9——localconditionsandengineeritherapiddevelopmentofhighwaytransportationinfrastructureinChina,bapavementdesigntheorieshavebeenimprovedandfurtherdeveloped.ThesehavebeensummarizedandabsorbedintheseSpecificationsforDesignofHighwayAsphaltPavement(JTGD50-2017).TheEnglishversionofthesespecificationsarethereforeissuedforthepurposeofsharingChineseexperiencewiththeprofessionalsintheworldandprovidereferencesforhighwaypavementdesignforsimilargeography,climateandgeologyofother——TheEnglishtranslationofthesespecificationswasconducCorporationundertheauthorizationoftheMinistryofTransportandapprovedbytheHighwayAdministrationoftheMinistryofTransport.ThecontentoftheEnglishversionareexactlythesameasthoseintheChineseversion.Ineventofanyambiguityordiscrepancies,theChineseversionshouldbereferredtoandaGratitudeisgivenherchargeoftheChineseversion,forthevaluableassistancandapprovaloftheEnglishversion.Comments，suggestionsandinquiriesarewelorganizationinchargeoftheEnAndingmenwaiDajie,Postalconsideredinfuturerevisions.ChinaRoadandBridgeZhangHuiyu,ZengFeng,Zhang———PrefacetoChineseVersionThehighwayinfrastructure,especiallythedesignandconstructionofasphaltpavementhasbeenrapidlydevelopedinlastdecades.Theapplicationofnewpavementmaterialhavewidenedengineeringchoiceandenrichedimplementationpractice.TheseraisedneedsforrevisingandupdatingtheindustrialstandardJTGD50-2006,‘SpecificationsofDesiPavement’,(refertoas‘thepreviousedition’hereinafter).AuthorizedbyMinistryofTransportofChina,themissionwasundertatenandfulfilledbyCCCCRoadandBridgeConsultantSupportedbydomesticandinternationaltechnictheprinciplesofheritanceanddevelopment,thiseditionhasmadeupdandemvironmentalfactors,designparameters,designcriteriaandrelevantperformacemoThiseditionofthespstructuraldesign,requirementsformaterialdesignparameters,calculationandverificationofpavementstructures,designforrehabilitation,designformeredition,majorchangesmadeinthisEditionoftheSpecificationsareasfollow2thetemperatureshiftfactorsandequivalenttemperaturehavebeenintro3thedesignparametersforpavementmatecalibrationandvalidationhavebeen4Newprovisionshavebeenaddedintermsofpermanentdeformationofasphaltbourndlayer,verticalcompressivestrainsatthetopofsubgradeandlowtemperahasbeenmadetothepredictionmodeloffatiguecrackingofasphaltboundlayersandchamecstabilizedlayers.Criteriaofroadsurfacedeflectionforpavementdesignhavebeenabolished.5Chaptersandsectionshavebeenreorstructuraldesign.TermsandsymbolChapter1,2and3ofthiseditionofthespecificationswerewrittenbyLiuBoying,Chapter4Shutao,Chapter5byNiuKaimin,Chapter6andAppendixBbyBaiQiChapter8andAppendicesDandEbydeflectionanalysiswaswrittenbyTangBomin,provisionsonpavmentlow-temporaturethermalcrackingwaswrittenbyFengDecheng,theprovisionsonmechanisticpmaterialsandthefatiguethedraftingforchf———Questionsandcommentsarewelcomeandspecifications,contactperson:LiuBoying(mailaddress:D88AndingmenwaiDajie,BeigjinChina,Ptcode:100011;Tel.8610-82016537;Fax:86;Wechat:goodpave.)FeedbacksshallbeEditingOrganizationinCharge:CCCCRoadandBredAssocitedEditingOrganization:AcadamyofHighwayScienceandTechnologyMoTJiangsuTransportScienceResearchInChongqingJiaotongUSouthChinaUniversiDalianUniversityofTechnolCCCCHighwayConsultantHarbinInstituteofTechnCCCCFirstHighwayConsultanLeadingEditorLiAssociatedEditors:OtherParticipants:WeiReviewEditorOtherReviewers:1GENERALPROVISIONS1.0.1Thesespecificationsareformulatedtocopewiththeneedsfordevelopmentofhighwayindustryandhighwayinfrastructure,toimprovedesignqualityandserviceperformanceofasphaltpavementsoastoensuresafety,durability,economical,andfitnesstopurposesofthehighwayworks.1.0.2Thesespecificationsareapplicabletoasphaltpavementdesignfornewconstructionandrehabilitationofclassifiedhighways.1.0.3Pavementstructures,pavementmaterialsandpavementthicknessesshallbedesignedinaccordancewiththeclassificationofthehighway,therequiredpavementserviceperformanceandthetrafficvolumetobeaccommodated,consideringphysicalfactorssuchasclimate,hydrology,geology,materials,andtakingconstructionandmaintenanceconditions,relevantpracticalexperiencesandenvironmentalprotectionrequirementsintoaccount.Adesignstrategyshallbeselectedthroughtechnicalandeconomicalevaluationonvariousalternatives.1.0.4Highwaysubgradeshallbeincompliancewiththelowestcriteriaforresilientmodulusandshallbemaintainedatasuitablemoisturelevel.Siteinvestigationsshallbecarriedouttoidentifylocalgeotechnicalconditionsandmoisturelevels,basedonwhichanintegrateddesignforbothsubgradesandpavementsshallbeconducted.1.0.5Newlydevelopedtechnologies,structures,materialsandconstructionmethodsareencouragedandshallbeadoptedinaproactivebutprudentwaybaseduponlocalenvironmentsandpracticalexperiences.1.0.6Apavementdesignfortheareasofdesert,expansivesoilorsaltysoilshallnotonlycomplywiththeprovisionsinthesespecifications,butalsoembracespecifictechnicalmeasuresbasedonlocalpracticalexperienceandresearchachievementtoeffectivelysolvethesoilproblemsuniquetotheregion.1.0.7Besidesthesespecifications,asphaltpavementdesignshallcomplywithrelevantprovisionsinprevailingnationalandindustrialstandards.—2—2TermsandSymbols2.1.1asphaltpavementThepavementwithanasphalticsurfacecourse.2.1.2ReliabilityTheprobabilitythatapavementstructurewillperformitsintendedfunctionoveraspecifiedperiodoftimeandundercertainconditions.Targetreliabilityisdefinedasthereliabilityrequiredforadesignedstructuretoachieve.2.1.3ReliabilityindexAnumericalcriteriononthereliabilityofpavementstructures.Atargetreliabilityindexisdefinedastheonespecifiedinthesespecificationstobeusedasbasicdataforpavementstructuraldesigns.2.1.4PavementdesignlifeThepredeterminedlengthoftimeforwhichapavementperformsinnormalconditionsofdesign,construction,operationandmaintenanceuntilstructuralrehabilitationisrequired.2.1.5DesignaxleloadsCalculatingaxleloadadoptedforpavementstructuraldesign2.1.6EquivalentsingleaxleloadsThenumberofdesignaxleloadsthatareequivalentindamagingeffectonapavementtoagivenvehicleoraxleloading2.1.7Cumulativeequivalentsingleaxleloads（CumulativeESAL）Thesumofequivalentsingleaxleloads(ESAL)appliedonthedesignlanefortheperiodofdesignlife.2.1.8sealcoatAfunctionlayerinpavementstructure,whichpreventsdownwardwaterinfiltration.2.1.9TackcoatAfunctionlayerormembraneprovidingbondinapavementstructure.2.1.10primecoatAfunctionlayerormembraneappliedonthesurfaceandpenetratedintoacertaindepthofanon-asphaltmateriallayer,toimproveintegrationofnon-asphltlayerandasphaltboundlayer.2.1.11drainagelayerThefunctionlayerfordrainingawaythewaterinfiltratedintoapavementstructure.2.1.12frostprotectionlayer—3—Thefunctionlayerforpreventingfrostwithinapavementstructure.2.1.13subgradeequilibriummoistureThesubgrademoisturethatreachestostableequilibriumstatewithsurroundingenvironmentalmoisture.2.1.14lowtemperaturethermalcrackingindexTheindicatorthatdescribesthelevelofshrinkagecrackingatlowtemperature.Cl——lowtemperaturethermalcrackingindexE——modulusG*——bindercomplexshearmodulush——Thicknessl——deflectionN——numberofaxleloadsP——axleloadsR——strengthRa——permanentdeformationofasphaltmixtureSt——asphaltstiffnessmoduluss——standarddeviationT——temperatureε——strainσ——stressβ——targetreliabilityindex —4—3DesignCriteria3.0.1ThetargetreliabilityandtargetreliabilityindexofapavementstructureshallnotbelessthanthecriteriaspecifiedinTable3.0.1.Table3.0.1TargetReliabilityandTargetReliabilityIndexβ3.0.2Thedesignlifeofanewasphaltpavementshallbedeterminedinaccordancewiththehighwayclassification,economicsandtrafficloadclassandshallnotbeshorterthanthecriterialistedinTable3.0.2Table3.0.2PavementDesignLife(inyears)HighwayClassificationDesignLifeHighwayClassificationDesignLifeMotorway,Class-1highwayClass-3highwayClass-2highwayClass-4highway83.0.3Pavementdesignshallusea100kNsingleaxle-dualtireloadasthedesignaxleload.CalculationparametersshallbedeterminedinaccordancewithTable3.0.3below.Thecumulativeequivalentsingleaxleload(cumulativeESAL)shallbedeterminedbythepavementdesignlifeinaccordancewithAppendixAoftheseSpecifications.Table3.0.3ParametersofdesignloadsDesignloads(kN)Tirecontactpressure(MPa)Equivalentdiameterofsingletirecontactarea（mm）0.70213.03ThetrafficloadsappliedonpavementstructureshallbeclassifiedasshowninTable3.0.4.Table3.0.4Classificationofdesigntrafficloadvehicle）inthedesignlaneduringdesignlifeNote:BusesandtrucksarethevehiclesClass2toClass11aslistedinTableA.1.2ofAppendixAoftheseSpecifications.3.0.5Asphaltpavementdesignshallprovidecontrolsonfatiguecrackingofasphaltboundmateriallayersor 5———chemicallystabilizedmateriallayers,permanentdeformationinasphaltboundlayers,verticalcompressivestrainonsubgrade,andlowtemperaturethermalcrackinginseasonalfrostregions.3.0.6Thecriteriaforpavementperformancedesignshallcomplywiththefollowingrequirements.1Thefatiguelifeofanasphaltboundlayerorachemicallystabilizedlayer,whichispredictedinaccordancewithAppendicesB.1orB.2,shallnotbelessthanthecumulativeESALduringthedesignlife.2Forasphaltboundmateriallayers,thepermanentdeformationcalculatedinaccordancewithAppendixB.2oftheSpecifications,shallnotgreaterthantheallowableamountofpermanentdeformation.Table3.0.6AllowabletotalpermanentdeformationofasphaltboundlayersAllowabletotalpermanentdeformationofasphaltboundlayersChemicallystabilizedbase,CementconcretasphaltboundbaseonchemicallystabilizedOthertypesofbase3TheverticalcompressivestrainonthesubgradeshallnotbegreaterthantheallowablevaluescalculatedinaccordancewithAppendixB.4.4Lowtemperaturethermalcrackingindices,calculatedinaccordancewithAppendixB.5oftheSpecificationsforseasonalfrostregions,shouldnotbegreaterthanthevalueslistedinTable3.0.6-2.Lowtemperaturethermalc357Note:Lowtemperaturethermalcrackinginduringtaking-overinspection.Atcrackthatdoesnotcrossovertheroadwaybutislongerthanthewidthlengthisshorterthanonelanewidth,thecrac3.0.7Formotorways,class-1highways,andtheclass-2orclass-3highwaysinmountainousorhillyterrains,taking-overinspectionsshallensuretheskidresistanceofpavementincompliancewiththecriteriainTable3.0.7.Table3.0.7CriteriaforskidresistanceCriteriafortaking-overSFC60a —6— —7—4PAVEMENTSTRUCTURALDESIGN4.1.1Thestructuraldesignofapavementshallbebasedonafullunderstandingofthecharacteristicsofvariouspavementstructuresintermsofmechanisticresponses,servicefunctionsandlong-termdeteriorationanddamageprocesses,andshallbeguidedbytheconceptofsystematicapproachforthesubgrade-pavementinteractioninordertoprovideapavementwithsafetyanddurabilityandlife-cyclecosteffectiveness.4.1.2Apavementstructuremaybeacombinationofsurfacecourse,basecourse,subbasecourseandselectedorfunctionallayersasrequired.Wheretheupperasphaltlayerispavedseparatelyinlayersofdifferentmaterials,thesurfacecoursemaybefurtherdividedintowearingcourse,intermediatecourseandbindercourse.4.1.3Withintheperiodofdesignlife,thepavementshallhavenostructuraldamagebyfatigue,forwhichonlytherepairingofsurfacingfunctionsmaybeconducted.4.1.4Atackcoatshallbeappliedbetweenanytwoasphaltboundlayers.Asealcoat,withorwithoutprimecoat,shallbeappliedbetweenanasphaltboundlayerandanyothermateriallayer.NoteofEnglishversion:apenetratingprimecoatwillinhibitstrengthgainofastabilizedlayerandshouldnotbeused.”4.1.5Waterproofingordrainagefacilitiesshallbeinstalledtopreventorreducetheinfiltrationofprecipitationintopavementstructures.4.2.1Apavementstructureshallbeselectedinaccordancewithtrafficloadclassification,subgradeconditionsandotherrelevantfactors,andbytakingthepavementmaterialpropertiesandstructuralcharacteristicsintoaccount.4.2.2Asphaltpavementstructuresmaybeclassifiedintofourtypesintermsofthematerialpropertiesofthepavementbase,thatis,asphaltpavementwithchemicallystabilizedbase,asphaltpavementwithunboundgranularbase,asphaltpavementwithasphaltboundbaseandasphaltpavementwithcementconcretebase.Theselectionofpavementstructuresshouldcomplywiththefollowingcriteria:1Anasphaltpavementwithachemicallystabilizedbaseissuitableforallclassifiedtrafficloads;2Anasphaltpavementwithanunboundgranularmaterialbaseissuitableforheavyorlowerclassifiedtrafficloads3Anasphaltpavementwithanasphaltboundbaseissuitableforallclassifiedtrafficloads.4Anasphaltpavementwithacementconcretebaseissuitablefortheheavy,veryheavyandextra-heavyclassifiedtrafficloads.4.2.4Anunboundmaterialbaseoranadditionalsubgradeimprovementlayerofunboundmaterialshouldbeselectedwherethesubgradeisinwetormoderatelywetstatus.4.2.5Inhighrainfallregions,specialmeasuresshallbearrangedforcontrollingpumpingandtheresultant —8—voidformationandotherwaterinitiateddistressesofpavementswherechemicallystabilizedmaterialsorcementconcreteslabsareusedaspavementbase,4.2.6Ifchemicallystabilizedmaterialsareselectedaspavementbase,oneorseveralofthefollowingmeasuresmaybeselectedforcontrollingshrinkagecrackinginthebasecourseandresultantreflectioncracking:1toselectthechemicallystabilizedmaterialswithhighcrackingresistantpropertiesasbasecourse;2toincreasethethicknessofasphaltboundlayersortoaddalayerofeitherasphalttreatedcrushedstonesorgradedunboundaggregatesontopofthechemicallystabilizedbase;3toplaceanadditionallayerofmodifiedasphaltasastressabsorptionmembraneinterlayer(SAMI)oralayerofgeosyntheticmaterialontopofthechemicallystabilizedbase.4.2.7Afterthepavementstructureisselected,thethicknessofeachstructurallayermaybedeterminedinaccordancewithtrafficloadsclassificationasdescribedinAppendixCoftheseSpecifications.4.3.1Thehighwaysubgradeshallbestable,wellcompactedanduniform,andshallhavesufficientbearingcapacity.4.3.2Forroadsectionsinearthorsoilcuttingsandcuttingswithseverelyweatheredgeologyinhighrainfallareas,specialattentionshallbepaidtothedrainagedesignoftransitionsegmentsbetweencuttingandembankmentfillforthepurposeofimprovingmoistureconditionsofthesubgrade.4.3.3Forrockcuttingsorrockfillsections,alevelinglayerabout200~300mmshallbeplacedbeneaththesubbasecourse.4.3.4Theroadbedofanewhighwayshallbeindryormoderatelywetcondition.Specificmeasuresshallbetakentopreventsubgradefrominfiltrationofeithersurfacewaterorgroundwater.4.4.1Thebaseandsubbaseofapavementshallhavesufficientbearingcapacityandfatigueresistance,aswellassufficientdurabilityandmoistureresistance.Inaddition,theasphaltboundbaseorchemicallystabilizedbaseshallhavesufficientresistancetopermanentdeformation.4.4.2BaseorsubbasematerialsmaybeselectedbyreferringtoTable4.4.2.MaterialSuitableTrafficLoadsandStructuralLayersCement-flyashstabilizeLime-flyashstabilizedgradedaggBaseandsubbaseforallclassesoftLime-flyashstabilizedall-inagSubbaseforallclassesoftCement,limeorlime-flSubbaseforallclassesoftUnboundgranularBaseforheavyorlighSubbaseforallclassesoftAll-inaggregates,naturalgraBaseformediumorligSubbaseforallclassesoft—9—Densegraded,asphalttreatedcrSemi-opengraded,asphalttreatedcrOpen-graded,asphalttreatedcrushBaseforextra,veryheavyBitumenpenetrationBaseforheavyorbelowheavytraffi4.4.3Recycledasphaltboundmaterialsandrecycledchemicallystabilizedmaterialsmaybeusedasbaseorsubbaseforallclassesoftrafficloads.Therecycledasphaltboundmaterialstobeusedasbasecourseforextraheavy,veryheavyorheavyclassoftrafficloadsshouldbeprocessedbyplanthotmixing.4.4.4Alayerofgradedunboundcrushedstoneoralayerofopengradedorsemi-opengradedasphalttreatedcrushedstonemaybeplacedbetweenthechemicallystabilizedlayerandtheasphaltboundlayer.4.4.5ThethicknessofbaseandsubbaseofvariousmaterialsshouldcomplywiththecriterialistedTable4.4.5.NorminalmaximumaggregatesizeDensegraded,asphalttreatedcSemi-opengraded,asphalttreatedOpengraded,asphalttreateBituminouspenetrationm/ChemicallystabilizedAll-inaggregates,naturalsand4.4.6ThecementconcretebaseofanasphaltpavementshallcomplywithrelevantprovisionsofthecurrentJTGD40DesignSpecificationsforHighwayCementConcretePavements.4.5.1Thesurfacecourseshallhavepropertiesofevennessandresistanceagainstrutting,fatigue,lowtemperaturethermalcrackingandwaterdamaging.Theasphaltmixturematerialsofawearingcourseshallhavethepropertiesofskidresistanceandwearingresistance,whileadensegradedasphaltmixtureofwearingcourseshallhavethepropertyoflowpermeability.4.5.2ThetypesofsurfacingmaterialsshouldbeselectedinaccordancewithTable4.5.2. TypeofMaterialSuitableTrafficLoadsandStructuralLayersContinuouslygradedasphaltmixtureSurfacelayer,intermediatelayerorbinderlayerforallclassesofloadsStonematrixasphalt(SMA)mixtureSurfacelayerforextraheavy,veryheavyorheavyclassoftrafficloads,orSurfacelayerforspecialskidresistancerequirementsPlanthotrecycledasphaltmixtureSurfacelayer,intermediatelayerorbinderlayerforallclassesofloadsHotmixonbituminousmacadamSurfacecourseformediumorlightclassoftrafficloadsBituminoussurfacedressingWearingcourserformediumorlightclassoftrafficloads4.5.3Anopengradedbituminousmixturemaybeusedassurfacelayerforspecificrequirementssuchasskidresistance,drainageornoisereduction.Asealcoatlayershallbeplacedundertheporoussurfacelayer,whichmaybemadeofmodifiedbituminousemulsionormodifiedasphaltwithsmallchips.(NOTEforEN)4.5.4ThelayerthicknessofanasphaltmixtureforvariousnominalsizesshallbeincompliancewiththecriteriaspecifiedinTable4.5.4.Thelayerthicknessofeithercontinuouslygradedasphaltmixtureorstonematrixasphalt(SMA)mixtureshouldnotbesmallerthan2.5timesitsnominalmaximumaggregatesize(NMAS).Thelayerthicknessofanopengradedasphaltmixtureshouldnotbelessthan2.0timesitsnominalmaximumaggregatesize(NMAS).TypeofasphaltmixtureMinimumlayerthicknessofasphaltmixturefornominalmaximumaggregatesize(mm)4.759.526.5Continuouslygraded2535405075Stonematrix-30405060-Opengraded-202530--4.5.5Thethicknessshouldbe40～80mmforalayerofbitumenpenetrationmacadamandnotmorethan50mmforalayerofbituminousemulsionpenetrationmacadam.Thethicknessofhotmixasphaltlaidontopofabituminouspenetrationlayershouldnotbelessthan25mm.4.5.6Asphaltsurfacedressingmaybeinone,twoorthreelayers.Thethicknessshouldbe10～15mmforsinglesurfacedressing,15～25mmfordoublesurfacedressing,and25～30mmfortriplesurfacedressing. 4.6.1Inseasonalfrostregions,anadditionallayerforfrostprotectionshallbeplacedifthepavementthicknessdoesnotsatisfythefrostrequirements.Afrostprotectionlayershouldbemadeofcoarsesand,sandgravel,crushedstoneorothergranularmaterials.4.6.2Fortheroadsectionswithahighwatertableandunfavorabledrainageconditionsorfortherocksectionsincuttingwithfracturegroundwater,springsorotheradversehydraulicconditions,anadditionallayerofgranularmaterialsshallbeplacedbetweenbaseorsubbaseandsubgradeifsuchabaseorsubbaseismadeofnon-granularmaterials.Thisunboundgranularlayershallbeextendedtosubgradeedgesorconnectedwiththefiltertrenchesbeneathsidedrains.4.6.3Asealcoatshouldbeplacedbetweenthechemicallystabilizedorcoldrecycledmateriallayerandtheasphaltboundlayer.Asealcoatcanbeasinglesurfacedressingorslurryseal.Asealcoatmaynotbeplacedinthecasewherethereisamodifiedasphaltlayerforstressabsorptioninthepavementstructure.4.6.4Modifiedbituminousemulsion,penetrationgradebitumenormodifiedbitumenshouldbeselectedandusedastackcoatsforextraheavy,veryheavyorheavyclassoftrafficloads;whilebitumenemulsionmaybeusedastackcoatsformediumorlightclassoftrafficloads;modifiedasphaltshouldbeusedasthetackcoatbetweenacementconcreteslabandanasphaltsurfacecourse.4.6.5Modifiedasphalt,penetrationgradebitumenorbituminousemulsionmaybeusedasthebinderforsealcoalsonasinglesurfacedressinglayer.Rubberizedbitumenshouldbeusedinthestressabsorbingmembraneinterlayer(SAMI)beneathamodifiedasphaltpavement.4.6.6Aprimecoatshouldbeprovidedonthesurfaceofeitheragranularbaseorachemicalstabilizedbase.Thebitumenusedforprimecoatingshallhavegoodpenetration,forwhichcutbackbitume