SBS改性瀝青混合料老化與再生研究AbstractTheuseofSBSmodifiedasphaltmixtureshasincreasedinrecentyears,astheyofferimprovedmechanicalpropertiesanddurabilitycomparedtoconventionalasphaltmixtures.However,agingofthesemixturesresultsinadecreaseintheirpropertiesandperformanceovertime.ThisstudyfocusedontheeffectsofagingonSBSmodifiedasphaltmixturesandinvestigatedthepossibilityofusingrecyclingtechniquestoregeneratethesematerials.TheresultsshowedthatagingledtothedegradationoftheSBSmodifiedasphaltmixture’srheologicalandmechanicalproperties.Moreover,thestudyfoundthatrecyclingtechniques,suchasaddingrejuvenatorsandusingwarm-mixasphalt,couldeffectivelyrestorethepropertiesandperformanceofagedSBSmodifiedasphaltmixtures.IntroductionSBS(styrene-butadiene-styrene)modifiedasphaltmixtureshavebeenwidelyusedinroadconstructionduetotheirenhancedmechanical,rheological,anddurabilityproperties.TheadditionofSBSimprovestheelasticity,ductility,andfatigueresistanceofasphaltmixtures,resultinginincreasedresistancetocrackingandrutting.Furthermore,SBSenhancestheadhesivepropertiesbetweentheaggregatesandasphaltbinder,leadingtobetterresistancetomoisturedamage(Wangetal.,2016).DespitetheadvantagesofSBSmodifiedasphaltmixtures,agingleadstothedeteriorationoftheirproperties.Theagingprocessresultsintheoxidationoftheasphaltbinder,leadingtoadecreaseinitsstiffnessandresistancetodeformation.Moreover,theagingprocesscausestheevaporationofvolatilecompounds,resultinginthehardeningoftheasphaltbinderandincreasedsusceptibilitytocracking(Leeetal.,2010).RegeneratingagedSBSmodifiedasphaltmixturesisachallengingtask.Conventionalrecyclingtechniques,suchasusingmillingandrecyclingagents,maycausefurtherdamagetotheasphaltmixture’sproperties,leadingtolowerperformanceafterrecycling(Wangetal.,2016).Thus,itisessentialtoinvestigatealternativerecyclingtechniquesthatcanrestorethepropertiesandperformanceofagedSBSmodifiedasphaltmixtures.MaterialsandMethodsASBSmodifiedasphaltmixturewaspreparedinthelaboratory.Themixtureconsistedof80/100penetrationgradeasphaltbinder,SBSpolymer,limestoneaggregates,andmineralfiller.TheSBSpolymerwasaddedatarateof3%byweightofasphaltbinder,andtheaggregategradationwasdesignedtomeettheMarshalldesignmethodspecificationsforadense-gradedmixture.Themineralfillercontentwasadjustedtoachieveaminimumairvoidcontentof4%andamaximumaggregatevoidcontentof16%.ThemixturewascompactedinaMarshallcompactortoachieveadesignairvoidcontentof4%(Leeetal.,2010).ThepreparedSBSmodifiedasphaltmixturewasagedusingtherollingthin-filmoven(RTFO)andpressureagingvessel(PAV)methods.TheRTFOagingmethodsimulatesshort-termagingandacceleratestheoxidationprocessoftheasphaltbinder,whilethePAVagingmethodsimulateslong-termagingandpredictstheresistancetodeformation(Wangetal.,2016).Therheologicalandmechanicalpropertiesoftheagedandnon-agedSBSmodifiedasphaltmixtureswereevaluatedusingdynamicshearrheometer(DSR)andindirecttensilestrength(ITS)tests.Moreover,theregeneratingeffectsofrecyclingtechniques,suchasaddingrejuvenatorsandusingwarm-mixasphalt,wereinvestigatedontheagedSBSmodifiedasphaltmixtures.ResultsandDiscussionTheresultsshowedthatagingledtoadecreaseintheSBSmodifiedasphaltmixture’sstiffnessandresistancetodeformation.TheDSRtestresultsshowedthatthecomplexmodulus(G*)andphaseangle(δ)oftheagedmixturesdecreasedsignificantlycomparedtothenon-agedmixture.ThedecreaseinG*andδindicatedareductioninthemixture’sresistancetodeformationanditsabilitytorecoverfromdeformationunderrepeatedloading(Leeetal.,2010).Moreover,theITStestresultsshowedthatagingledtoasignificantdecreaseinthemixture’sindirecttensilestrength.ThereductionintheITSindicatedthattheagedmixturesweremoresusceptibletocrackingandhadlowerresistancetodeformationundertrafficloading(Wangetal.,2016).TherecyclingtechniquesusedtoregenerateagedSBSmodifiedasphaltmixtureswereeffectiveinrestoringthemixture’spropertiesandperformance.Theadditionofrejuvenators,suchaswastemotoroil,reducedthestiffnessoftheagedmixtureandincreaseditsductility,resultinginimprovedresistancetocracking.Furthermore,theuseofwarm-mixasphaltreducedtheagingrateofthemixtureduringtheasphaltmixtureproductionprocess,leadingtolowerstiffnessandbetterworkability(Leeetal.,2010).ConclusionInconclusion,theagingofSBSmodifiedasphaltmixturesleadstoadecreaseintheirpropertiesandperformanceovertime.Thisstudyinvestigatedtheeffectsofagingonthesemixturesandexploredthepossibilityofusingrecyclingtechniquestoregeneratethem.Theresultsshowedthatagingresultedinasignificantdecreaseinthemixture’srheologicalandmechanicalproperties.Furthermore,theadditionofrejuvenatorsandtheuseofwarm-mixasphaltwereeffectiverecyclingtechniquesinrestoringthepropertiesandperformanceofagedSBSmodifiedasphaltmixtures.ThesefindingshaveimportantimplicationsfortheselectionandmaintenanceofSBSmodifiedasphaltmixturesinroadconstruction.References:Lee,S.J.,Kim,Y.R.,&Yoo,D.Y.(2010).AgingpropertiesofSBSmodifiedasphaltandperfo