瀝青抽提評(píng)價(jià)舊路材料性能的研究

瀝青抽提評(píng)價(jià)舊路材料性能的研究Chapter1:Introduction

-Backgroundandsignificanceofthestudy

-Researchobjectivesandquestions

-Scopeandlimitationsofthestudy

-Methodologyandresearchapproach

Chapter2:LiteratureReview

-Definitionandexplanationofasphaltextraction

-Previousresearchonevaluatingthepropertiesofreclaimedasphaltpavement(RAP)

-Discussionofasphaltbinderpropertiesandcharacterizationmethods

-Overviewoftheuseofrecycledmaterialsinasphaltmixtures

-ExaminationofthesustainabilityofusingRAPinasphaltmixtures

Chapter3:MaterialsandMethods

-SamplingandpreparationofRAPandvirginasphaltbinder

-Extractionandrecoveryofasphaltbinderusingsolventextractionmethod

-Evaluationofthephysicalandchemicalpropertiesoftheextractedbinders

-CharacterizationoftheRAPandvirginasphaltbinderusingrheologicaltests

Chapter4:ResultsandAnalysis

-ComparisonofphysicalandchemicalpropertiesoftheRAPandvirginasphaltbinder

-Rheologicalcharacterizationofthebinders

-EvaluationoftheeffectofRAPcontentontheperformanceofasphaltmixtures

-DiscussionofthesustainabilityofusingRAPinasphaltmixtures

Chapter5:ConclusionandRecommendations

-Summaryofkeyfindings

-ImplicationsofthestudyfortheuseofRAPinasphaltmixtures

-Limitationsandsuggestionsforfutureresearch

-RecommendationsforthepracticaluseofRAPinasphaltpavingoperations

-Finalthoughtsandconclusion.Chapter1:Introduction

Asphaltpavementisoneofthemostcommonlyusedroadsurfacesworldwide.Theproductionanduseofhotmixasphaltinvolvestheuseofasignificantamountofnaturalresources,makingitimportanttofindmoresustainableapproachestoroadconstruction.Onepotentialsolutionistheuseofreclaimedasphaltpavement(RAP)inasphaltmixtures.

RAPisthematerialthatisremovedduringasphaltpavementrehabilitationorreconstruction.Itistypicallycomposedofagedasphaltbinderandaggregate,withasmallamountofnewasphaltbinderaddedduringtherecyclingprocess.TheuseofRAPinasphaltmixturescanhelpreducetheamountofvirginmaterialsneededforroadconstruction,thusdecreasingtheenvironmentalimpactoftheprocess.

TheprimaryobjectiveofthisresearchistoevaluatethepropertiesofasphaltbinderextractedfromRAPandtodetermineitspotentialforuseinnewasphaltmixtures.Specifically,thisstudywillexaminethephysicalandchemicalpropertiesoftheextractedbinder,andcomparethemwiththoseofvirginasphaltbinder.Inaddition,therheologicalpropertiesofthebinderswillbecharacterized,andtheeffectofRAPcontentontheperformanceofasphaltmixtureswillbeevaluated.

Theresearchquestionsthatwillguidethisstudyare:

1.WhatarethephysicalandchemicalpropertiesoftheasphaltbinderextractedfromRAPcomparedtovirginasphaltbinder?

2.Whataretherheologicalpropertiesoftheextractedbinderandhowdotheycomparetothoseofvirginasphaltbinder?

3.HowdoestheRAPcontentinasphaltmixturesaffecttheirperformance?

4.WhatisthesustainabilityofusingRAPinasphaltmixtures?

ThescopeofthisstudywillbelimitedtotheevaluationofasphaltbinderextractedfromRAPanditspotentialuseinasphaltmixtures.Thestudywillnotconsidertheinfluenceofaggregatepropertiesontheperformanceofasphaltmixtures.TheapproachtakenwillinvolvelaboratorytestingandanalysisofsamplesofRAP,virginasphaltbinderandasphaltmixtures.

ThemethodologyusedinthisstudywillincludethesamplingandpreparationofRAPandvirginasphaltbinder,extractionandrecoveryofasphaltbinderusingsolventextractionmethod,evaluationofthephysicalandchemicalpropertiesoftheextractedbinders,andcharacterizationoftheRAPandvirginasphaltbinderusingrheologicaltests.Theexperimentalworkwillbecomplementedwithanalyticaltools,suchasFouriertransforminfraredspectroscopy(FTIR),toanalyzethechemicalcompositionofthebinder.

Theresultsofthisstudywillprovideinsightsintothephysical,chemical,andrheologicalpropertiesofasphaltbinderextractedfromRAP,anditspotentialforuseinasphaltmixtures.Additionally,thisresearchwillcontributetotheexistingknowledgeontheuseofrecycledmaterialsinasphaltpavingandthesustainabilityofroadconstruction.Chapter2:LiteratureReview

2.1HistoryofRAP

Thereuseofmaterialsinasphaltpavementsdatesbacktotheearly1900s,wherereclaimedasphaltwasaddedtonewasphaltmixturesfortheconstructionofroads.TheuseofRAPsawasignificantincreaseinthe1970sduetotheworldwideoilcrisis,whichmadeasphaltbindermoreexpensive.Therecyclingofasphaltmaterialsprovidedaneconomicalsolutionforroadconstructionwhilereducingtheenvironmentalimpactofasphaltproduction.

2.2RAPProductionandComposition

RAPisgeneratedduringtherehabilitationorreconstructionofasphaltpavements.TheamountofRAPproducedvariesdependingontheageandconditionoftheexistingpavement,aswellastheextentandtypeofrehabilitationworkrequired.RAPtypicallyconsistsofabout95%asphaltbinderand5%aggregate,withtheexactcompositionvaryingaccordingtothesourceandageofthepavement.

ThepresenceofagedasphaltbinderinRAPcanaffecttherheologyandperformanceofnewasphaltmixtures.TheagedbinderinRAPistypicallyharderandlessviscousthanvirginasphaltbinder,anditschemicalcompositioncanbealteredduetoexposuretosunlight,waterandotherenvironmentalfactors.

2.3PropertiesofRAP

ThepropertiesofRAPcanvarydependingonthesourceandageofthepavement.RAPtypicallyhasalowerviscosityandhigherpenetrationcomparedtovirginasphaltbinder.ThesofteningpointofRAPisalsolower,andtheductilityofRAPcanbereducedduetotheagingofthebinder.ThepropertiesoftheRAPbindercanalsobeimpactedbythepresenceofcontaminantsorotherforeignmaterials.

2.4RheologicalPropertiesofBinder

Therheologicalpropertiesofasphaltbinderareimportantfordeterminingtheperformanceofasphaltmixtures.Therheologicalpropertiesofthebindercanbemeasuredusingvarioustests,includingdynamicshearrheometer(DSR)andbendingbeamrheometer(BBR).Theresultsofthesetestsprovideinformationonthestiffness,ductility,andfatigueresistanceofthebinder,whichareimportantfactorsforevaluatingtheperformanceofasphaltmixtures.

2.5EffectsofRAPonAsphaltMixturePerformance

TheuseofRAPinasphaltmixturescanaffecttheirperformance.TheadditionofRAPcanreducetheamountofnewasphaltbinderneeded,whichcanleadtocostsavingsandreducetheenvironmentalimpactofasphaltproduction.However,theuseofRAPcanalsoimpacttherheologicalpropertiesoftheasphaltmixture,leadingtoareductioninperformance.

TheinclusionofRAPcanalsoaffectthepropertiesoftheasphaltmixture,includingitsstiffness,strength,anddurability.TheproportionofRAPintheasphaltmixturecanaffecttheseproperties,withhigherproportionsofRAPresultinginareductioninperformance.

2.6SustainabilityofRAPinAsphaltPavements

TheuseofRAPinasphaltpavementscanprovidesignificantsustainabilitybenefits.Theuseofrecycledmaterialsreducestheneedforvirginmaterials,whichcanhelptoconservenaturalresourcesandreducetheenvironmentalimpactofasphaltproduction.TheuseofRAPcanalsohelptoreducewasteandlandfill,aswellasreduceenergyconsumptionduringtheproductionofnewmaterials.

However,thesustainabilityofRAPusecanbeimpactedbyfactorssuchasthequalityoftheRAP,theamountofvirginasphaltbinderrequired,andthetransportdistanceoftheRAP.ItisimportanttocarefullyevaluatethesustainabilityofusingRAPinasphaltpavementstoensurethatitprovidesanetenvironmentalbenefit.

Overall,theliteraturesuggeststhattheuseofRAPinasphaltmixturescanoffersignificantsustainabilityadvantages,whilealsoreducingcostsandprovidingimprovedperformance.However,carefulconsiderationmustbegiventothepropertiesoftheRAPandtheproportionusedintheasphaltmixturetoensurethatitdoesnotnegativelyimpacttheperformanceorsustainabilityofthepavement.Chapter3:ExperimentalMethods

Inordertoevaluatetheperformanceofasphaltmixturescontainingreclaimedasphaltpavement(RAP),variousexperimentalmethodscanbeemployed.ThischapterwilldiscusssomeofthekeymethodsusedtoevaluatethepropertiesandperformanceofasphaltmixturescontainingRAP.

3.1BinderCharacterization

ThepropertiesoftheasphaltbinderinRAPcanbecharacterizedusinganumberofdifferenttests,includingtherotationalviscometer,dynamicshearrheometer(DSR),andbendingbeamrheometer(BBR).Therotationalviscometerisusedtomeasuretheviscosityoftheasphaltbinder,whiletheDSRandBBRareusedtomeasurethestiffnessandductilityofthebinder,respectively.ThesetestscanprovideimportantinformationontherheologicalpropertiesofthebinderandhowtheymaychangewiththeadditionofRAP.

3.2MixtureDesign

ThemixturedesignprocessforasphaltmixturescontainingRAPmusttakeintoconsiderationthepropertiesofboththenewandagedbinder.TheSuperpavemixdesignmethodiscommonlyusedforthispurpose,andinvolvesevaluatingthepropertiesofthevirginbinderandRAPbinderseparatelyandthendesigningthemixturewiththeappropriateamountofeachbinder.Additionally,theaggregategradationandproportionmustbecarefullyconsideredtoensurethatthemixturemeetsperformancerequirements.

3.3PerformanceTesting

VariousperformancetestscanbeconductedtoevaluatetheperformanceofasphaltmixturescontainingRAP.Somecommontestsincludethedynamicmodulustest,indirecttensilestrengthtest,andfatiguecrackingtest.Thesetestsprovideinformationonthestiffness,strength,anddurabilityoftheasphaltmixtureunderdifferentloadingandenvironmentalconditions.

3.4ImagingTechniques

ImagingtechniquessuchasX-raycomputedtomography(CT)andscanningelectronmicroscopy(SEM)canbeusedtoexaminethemicrostructureoftheasphaltmixturecontainingRAP.ThesetechniquescanprovidevaluableinsightsintohowtheadditionofRAPisaffectingthemicrostructureofthemixtureanditspotentialimpactonitsperformance.

3.5FieldPerformanceMonitoring

Finally,fieldperformancemonitoringcanbeusedtoevaluatethelong-termperformanceofasphaltpavementscontainingRAP.Thiscaninvolvevarioustechniquessuchaspavementroughnessmeasurements,rutdepthmeasurements,andvisualinspections.Thesemeasurementscanprovideinformationonhowthepavementisperformingintermsofridequality,durability,andsafety.

Overall,acombinationoftheseexperimentalmethodscanbeusedtoevaluatetheperformanceofasphaltmixturescontainingRAP.ItisimportanttocarefullyselecttheappropriatemethodsbasedonthespecificresearchgoalsandthepropertiesoftheRAPandasphaltmixturebeingstudied.Chapter4:FindingsandDiscussion

Inthischapter,wewilldiscussthefindingsofvariousstudiesontheperformanceofasphaltmixturescontainingreclaimedasphaltpavement(RAP).ThestudiesconsideredinthischapterutilizetheexperimentalmethodsdiscussedinChapter3andhavecontributedvaluableinformationtothefieldofasphaltpavementengineering.

4.1BinderCharacterization

SeveralstudieshaveinvestigatedtherheologicalpropertiesofasphaltbinderscontainingRAP.OnestudyfoundthattheadditionofRAPcanleadtoanincreaseinstiffnessandadecreaseinductilityofthebinder,whichcanaffecttheoverallperformanceoftheasphaltmixture(Al-Qadietal.,2006).AnotherstudyfoundthattheviscosityofthebindercandecreasewiththeadditionofRAP,leadingtoimprovedworkabilityandcompactionofthemixture(Khalidetal.,2017).ThesefindingssuggestthatcarefulconsiderationofthepropertiesofboththevirginandRAPbinderiscriticalforthesuccessfuldesignandperformanceofasphaltmixturescontainingRAP.

4.2MixtureDesign

TheSuperpavemixdesignmethodhasbeenwidelyusedfordesigningasphaltmixturescontainingRAP.SeveralstudieshaveinvestigatedtheimpactofRAPontheoptimalbindercontentandaggregategradationofthemixture.OnestudyfoundthatincreasingtheRAPcontentcanleadtoadecreaseinoptimalbindercontentandashiftintheaggregategradationtowardsfineraggregatesizes(YuandWang,2018).AnotherstudyfoundthattheRAPcontentcansignificantlyaffecttheoptimumasphaltcontentandthevolumetricpropertiesofthemixture(Sohrabietal.,2013).ThesefindingssuggestthatacarefulconsiderationofboththepropertiesofthebinderandtheaggregategradationiscriticalindesigningasphaltmixturescontainingRAP.

4.3PerformanceTesting

AnumberofstudieshaveinvestigatedtheperformanceofasphaltmixturescontainingRAPusingvariousperformancetests.OnestudyfoundthattheadditionofRAPcanincreasethestiffnessandfatigueresistanceofthemixture,whileanotherstudyfoundthatRAPcanleadtoareductioninthedynamicmodulusandindirecttensilestrengthofthemixture(Lietal.,2018;WangandLi,2016).ThesefindingssuggestthattheperformanceofasphaltmixturescontainingRAPcanvarydependingonthespecificmixturedesignandthetestingconditions.

4.4ImagingTechniques

ImagingtechniquessuchasX-raycomputedtomography(CT)andscanningelectronmicroscopy(SEM)havebeenusedtoexaminethemicrostructureofasphaltmixturescontainingRAP.OnestudyfoundthattheadditionofRAPcanleadtoamoreheterogeneousmicrostructurewithincreasedporosityandreducedinterfacialbondingbetweentheRAPandvirginaggregates(Wilderetal.,2019).AnotherstudyfoundthattheRAPparticlescanactasnucleationsitesforasphaltaging,leadingtotheformationofmorebrittlebinderwithinthemixture(Jenkinsetal.,2017).ThesefindingssuggestthatimagingtechniquescanprovidevaluableinsightsintothemicrostructuralchangesthatoccurwhenRAPisaddedtothemixture.

4.5FieldPerformanceMonitoring

Severalstudieshaveinvestigatedthelong-termperformanceofasphaltpavementscontainingRAPusingfieldperformancemonitoringtechniques.OnestudyfoundthatasphaltmixturescontainingRAPcanperformsimilarlytothosecontainingonlyvirginaggregatesintermsofruttingandcrackingperformance(Maupinetal.,2018).AnotherstudyfoundthattheuseofRAPcanleadtoimprovedpavementperformanceandextendedpavementlifecomparedtovirginasphaltmixtures(Dongetal.,2017).Thesefindingssuggestthatwithpropermixturedesignandconstructionpractices,asphaltmixturescontainingRAPcanperformwellinthefield.

Overall,thestudiesreviewedinthischapterprovidevaluableinsightsintothepropertiesandperformanceofasphaltmixturescontainingRAP.WhiletheuseofRAPcanleadtosomechallengesinmixturedesignandperformancetesting,properconsiderationofthepropertiesofboththevirginandRAPbinder,aggregategradation,andconstructionpracticescanleadtosuccessfuloutcomes.MoreresearchmaybeneededtoexploretheuseofRAPindifferentpavementapplicationsandtofurtherrefinemixturedesignandperformancetestingmethodsforasphaltmixturescontainingRAP.Chapter5:ConclusionandFutureResearch

Theuseofreclaimedasphaltpavement(RAP)inasphaltmixtureshasbecomeincreasinglyprevalentinthepastfewdecadesduetoitsenvironmentalandeconomicbenefits.However,theadditionofRAPtothemixturecanalsoleadtosomechallengesinmixturedesignandperformancetesting.ThestudiesreviewedinthispaperhaveprovidedvaluableinsightsintothepropertiesandperformanceofasphaltmixturescontainingRAP,aswellasthepotentialsolutionstoovercomethesechallenges.

Intermsofbindercharacterization,theadditionofRAPcanleadtoanincreaseinstiffnessandadecreaseinductilityofthebinder,whichcanaffecttheoverallperformanceoftheasphaltmixture.TheviscosityofthebindercanalsodecreasewiththeadditionofRAP,leadingtoimprovedworkabilityandcompactionofthemixture.ThesefindingssuggestthatacarefulconsiderationofthepropertiesofboththevirginandRAPbinderiscriticalforthesuccessfuldesignandperformanceofasphaltmixturescontainingRAP.

TheSuperpavemixdesignmethodhasbeenwidelyusedfordesigningasphaltmixturescontainingRAP.SeveralstudieshaveinvestigatedtheimpactofRAPontheoptimalbindercontentandaggregategradationofthemixture.IncreasingtheRAPcontentcanleadtoadecreaseinoptimalbindercontentandashiftintheaggregategradationtowardsfineraggregatesizes.TheRAPcontentcansignificantlyaffecttheoptimumasphaltcontentandthevolumetricpropertiesofthemixture.AcarefulconsiderationofboththepropertiesofthebinderandtheaggregategradationiscriticalindesigningasphaltmixturescontainingRAP.