Charactrization Tests for Mineral Fillers Related to Performance of Asphalt Paving Mixtures

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    CHARACTERIZATIONTESTSFORMINERALFILLERSRELATEDTOPERFORMANCEOFASPHALTPAVINGMIXTURES

    By

    PrithviS.Kandal

    CynthiaY.LynnFrazierParker

    PaperpublishedinTransportationResearchBoard,TransportationResearchRecord1638,1998

    277TechnologyParkway Auburn,AL36830

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    CHARACTERIZATIONTESTSFORMINERALFILLERSRELATEDTO PERFORMANCEOFASPHALTPAVINGMIXTURES

    By

    PrithviS.Kandhal

    AssociateDirectorNationalCenterforAsphaltTechnology

    AuburnUniversity,Alabama

    CynthiaY.Lynn

    GraduateStudentNationalCenterforAsphaltTechnology

    AuburnUniversity,Alabama

    FrazierParkerDirector

    HighwayResearchCenterAuburnUniversity,Alabama

    PaperpublishedinTransportationResearchBoard,TransportationResearchRecord1638,1998

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    DISCLAIMER

    Thecontentsofthisreportreflecttheviewsoftheauthorswhoaresolelyresponsibleforthefactsandtheaccuracyofthedatapresentedherein.ThecontentsdonotnecessarilyreflecttheofficialviewsandpoliciesoftheNationalCenterforAsphaltTechnologyofAuburnUniversity.Thisreportdoesnotconstituteastandard,specification,orregulation.

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    ABSTRACT

    Variousstudieshaveshownthatthepropertiesofmineralfillerespeciallythematerial

    passing0.075mm(No.200)sieve(generallycalledP200material)haveasignificanteffectontheperformanceofasphaltpavingmixturesintermsofpermanentdeformation,fatiguecracking,andmoisturesusceptibility.However,researchershaveemployeddifferentcharacterizationtestsforevaluatingtheP200materials.

    ThisstudywasundertakentodeterminewhichP200characterizationtestsaremostrelatedtothe

    performanceofasphaltpavingmixtures.SixP200materialsrepresentingawiderangeofmineralogicalcompositionandparticlesizeswereused.TheseP200materialswerecharacterizedbysixtestsincludingRigdenvoids,particlesizeanalysis,andmethylenebluetest.Mixeswerepreparedwithtwofines/asphaltratios(0.8and1.5)byweight.MixvalidationtestsincludedtheSuperpavesheartestforevaluatingpermanentdeformationandfatiguecracking,andtheHamburgwheeltrackingtestandAASHTOT283forevaluatingmoisturesusceptibilityofthe12mixturescontainingdifferentP200materialsandfines/asphaltratios.

    Theparticlesizesinmicronscorrespondingto60and10percentpassingandthemethylenebluetestweredeterminedtoberelatedtotheperformanceofasphaltpavingmixtures.

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    Kandhal,Lynn,&Parker

    CHARACTERIZATIONTESTSFORMINERALFILLERSRELATEDTO

    PERFORMANCEOFASPHALTPAVINGMIXTURESPrithviS.Kandhal,CynthiaY.Lynn,andFrazierParkerJr.

    INTRODUCTION

    Accordingtovariousstudiesthepropertiesofmineralfillerespeciallythematerialpassing0.075mm(No.200)sieve(generallycalledP200material)haveasignificanteffectontheperformanceofasphaltpavingmixturesintermsofpermanentdeformation,fatiguecracking,andmoisturesusceptibility.However,researchershaveemployeddifferentcharacterizationtestsforevaluatingtheP200materials.ThisstudywasundertakentodeterminewhichP200characterizationtestsaremostrelatedtotheperformanceofasphaltpavingmixtures.

    REVIEWOFLITERATURE

    Numerousstudieshaveshownthatthepropertiesofmineralfiller(especiallythematerialpassingNo.200sieve)haveasignificanteffectonthepropertiesoftheHMAmixtures.Theintroductionofenvironmentalregulationsandthesubsequentadoptionofdustcollectionsystem(baghouse)hasencouragedthereturnofmostofthefinestotheHMAmixture.Amaximumfiller/asphaltratioof1@2to1@5,basedonweight,isusedbymanyagenciestolimittheamountoftheminus200material.However,thefinesvaryingradation,particleshape,surfacearea,voidcontent,mineralcomposition,andphysico-chemicalpropertiesand,therefore,theirinfluenceonthepropertiesofHMAmixturesalsovaries(1).Therefore,themaximumallowableamountshouldbedifferentfordifferentfines.

    FinescaninfluencetheperformanceofHMAmixturesasfollows.

    1.Dependingontheparticlesize,finescanactasafillerorasanextenderofasphaltcementbinder(2,3,4).Inthelattercaseanover-richHMAmixcanresultleadingto

    flushingand/orrutting.Inmanycases,theamountofasphaltcementusedmustbereducedtopreventalossofstabilityorableedingpavement(5).2.Somefineshaveaconsiderableeffectontheasphaltcementmakingitactasamuch

    stiffergradeofasphaltcementcomparedtotheneatasphaltcementgrade(1,3,6,7),andtherebyaffecttheHMApavementperformanceincludingitsfracturebehavior(8,9).

    3.SomefinesmaketheHMAmixturessusceptibletomoisture-induceddamage(1).Water-sensitivityofonesourceofslagbaghousefineshasbeenreportedintheUnitedStates(5),andthewater-sensitivityofotherstonedustshasbeenreportedinGermany(10).StrippingofHMAmixturesasrelatedtothepropertiesoffiller/asphaltcombinations(fillerswereobtainedfromoperatingHMAplants)hasbeenreportedinJapan(11).

    ItisveryimportanttocharacterizethefinessothattheperformanceparametersofHMApavements(resistancetopermanentdeformation,stripping,andfatiguecracking)arenotcompromised.

    MATERIALS,TESTS,ANDTESTDATA

    P200MaterialsandTests

    Sixaggregatesources(Table1)werechosentorepresentawiderangeofmineralogicalcompositionandparticlesizes.Thesematerialswereobtainedbydrysievingfineaggregateparentrockovera75:m(No.200)sieve.

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    Table1.P200AggregateTestsResults

    P-200TypeTest

    P200-1 P200-2 P200-3 P200-4 P200-5 P200-6Natural Lime- Dolomite Granite Blast LimerockSand stone Furnace

    Slag

    SpecificGravity 2.558 2.760 2.955 2.872 3.043 2.798

    RigdenVoid(British 39.3 35.4 32.3 41.4 40.6 34.3Standard),%

    RigdenVoid 53.8 38.0 38.9 45.5 49.8 38.5(PennStateModified),%

    FinenessModulus 3.67 2.46 4.99 4.50 4.47 2.81

    D10(micron) 1.54 1.26 4.18 3.30 2.41 1.38D30(micron) 6.45 3.27 22.58 15.64 12.67 4.23

    D60(micron) 26.92 9.98 51.95 40.89 43.41 14.60

    SpecificSurfaceArea 12900 17968 6207 7206 8752 15603(cm2/ml)

    MethyleneBlue 18.7 1.3 0.3 2.1 2.0 9.5

    PlasticityIndex 29 NP NP NP NP NP

    GermanFillerTest 35 70 80 60 55 75

    ThefollowingtestswereusedtocharacterizetheP200materials.RigdenVoids(BritishStandard)-BS812RigdenVoids(PennStateModified)-Reference13ParticleSizeAnalysisMethyleneBlueTest-OhioDOTProcedurePlasticityIndex-AASHTOT90GermanFillerTest-KochMaterialsCompanyProcedure

    Voidcontentinfines(generallycalledRigdenvoids)compactedtomaximumdensityhasbeenusedbyresearchersforcharacterizingthefines.Voidcontentisregulatedbyfourbasicpropertiesoffinesparticleshape,particlesize,particle-sizedistribution,andparticlesurfacestructure(1).Asampleofvacuum-ovendrysampleoffinesiseithervibratedinagraduatecylinder(1)orcompactedinasmallmoldbyacompactionhammer(12,13)tomaximum

    packing.Mass(g)ofthecompactedfinesisdividedbythecompactedvolume(cm3)tocalculatebulkspecificgravity(GfB)ofcompactedfines.Apparentspecificgravity(GfS)ofthefinesolidsisdeterminedbyAASHTOT133usingkerosene.Voidcontent(V)inthefinescompactedtomaximumdensityisthencalculatedasfollows:BothBritishStandardBS812(12)andPennStatemodifiedequipment(13)wereusedtodetermineRigdenVoids.Theyarebasedonthesameconceptbutuseadifferentcompactive

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    effort.

    ParticlesizeanalysiswasconductedwithaCoulterLF200Particlesizeanalyzer.Fromthis

    analysis,severalparametersweredetermined.Therelativefinenessofanaggregatecanbe

    determinedbythecalculatedfinenessmodulus(FM).FinenessmodulusoftheP200materialwascalculatedbydividingby100thesumofthepercentagesofP200materialcoarserthan75,50,30,20,10,5,3,and1microns.Thefinertheaggregate,thesmallerthefinenessmodulus.ParametersD10,D30,andD60werealsodeterminedfromparticlesizeanalysis.Theseparametersaretheparticlesizesthatcorrespond,respectively,to10,30,and60%ofthematerialpassing.Thespecificsurfacearea(cm2/ml)orSAwasthefinalparameterobtainedfromthisanalysis.

    Themethyleneblue(MB)testisusedbytheInternationalSlurrySealAssociation(ISSA)to

    quantifytheamountofharmfulclaysofthesmectite(montmorillinite)group,organicmatterandironhydroxidespresentinfineaggregate(14).Theprincipleofthetestistoaddquantitiesofastandardaqueoussolutionofthedye(methyleneblue)toasampleuntiladsorptionofthedye

    ceases.TheGermanfillertestisameasureoftheamountofmineralfillerrequiredtoabsorb15grams

    ofhydraulicoil.Thehydraulicoilisputinasmallbowl,then45gramsofmineralfillerisaddedandmixed.Anattemptismadetoformaballwiththemixture.Ifaballisformedandholdstogether,moremineralfiller,in5-gincrements,isadded.Thisprocessiscontinueduntilthemixturelosescohesion.Atthispoint,allofthehydraulicoilisfixedinthevoidsoftheP200materialandthereisnoexcesstoholdtheparticlestogether.ThetotalamountofP200addedtothehydraulicoilisreportedasthetestvalue.

    Table1containstheresultsoftheP200characterizationtests.Eachvalueistheaverageofthree

    replicates.

    Table2containsthecorrelationmatrixbetweenaggregateproperties.Thecorrelationcoefficients(Rvalues)arethefirstnumberineachcell.Thesecondnumberineachcellisthestatisticalsignificancelevel(P)correspondingtothecorrelationcoefficient.

    Rigdenvoids,BritishmethodandRigdenvoids,PennStatemodifiedhaveagoodcorrelation

    (R=0.78,P=0.06)witheachotherbecausebothmeasurethevoidsinthecompactedP200materialalthoughwithdifferentcompactiveefforts.Rigdenvoids,PennStatemodified,hasanexcellentcorrelationwiththeGe