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Tests for Plastic Fines in Aggregates Related to Stripping in Asphalt Paving Mixtures

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  • 8/9/2019 Tests for Plastic Fines in Aggregates Related to Stripping in Asphalt Paving Mixtures

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    TESTSFORPLASTICFINESINAGGREGATESRELATEDTOSTRIPPINGINASPHALTPAVINGMIXTURES

    By

    PrithviS.Kandal

    CynthiaY.LynnFrazierParker

    PublishedintheJournaloftheAssociationofAsphaltPavingTechnologists,AsphaltPavingTechnology,Volume67,1998

    277TechnologyParkway Auburn,AL36830

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    TESTSFORPLASTICFINESINAGGREGATESRELATEDTOSTRIPPINGINASPHALTPAVINGMIXTURES

    By

    PrithviS.Kandhal

    AssociateDirectorNationalCenterforAsphaltTechnology

    AuburnUniversity,Alabama

    CynthiaY.Lynn

    GraduateStudentNationalCenterforAsphaltTechnology

    AuburnUniversity,Alabama

    FrazierParkerDirector

    HighwayResearchCenterAuburnUniversity,Alabama

    PublishedintheJournaloftheAssociationofAsphaltPavingTechnologists,AsphaltPavingTechnology,

    Volume67,1998

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    DISCLAIMER

    Thecontentsofthisreportreflecttheviewsoftheauthorswhoaresolelyresponsibleforthefactsandtheaccuracyofthedatapresentedherein.ThecontentsdonotnecessarilyreflecttheofficialviewsandpoliciesoftheNationalCenterforAsphaltTechnologyofAuburnUniversity.Thisreportdoesnotconstituteastandard,specification,orregulation.

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    ABSTRACT

    Thisstudywasundertakenfordeterminingthebestaggregatetestmethodthatindicatesthe

    presenceofdetrimentalplasticfinesinthefineaggregate,whichmayinducestrippinginhotmixasphalt(HMA)mixtures.

    Tenfineaggregatesrepresentingawiderangeofmineralogicalcompositionsandplasticity

    characteristicswereused.Theirplasticitycharacteristicswereevaluatedbythreetestmethods:(a)sandequivalentvalue,(b)plasticityindex,and(c)methylenebluevalue.TenHMAmixturesweremadeusingacommonlimestonecoarseaggregatebutthesedifferentfineaggregates.Superpavevolumetricmixdesignwasusedtoestablishtheoptimumasphaltcontents.Twomixvalidationtests:(a)AASHTOT283and(b)theHamburgwheel-trackingdevicewereusedtoevaluatethestrippingpotentialofthetenHMAmixtures.

    Statisticalanalysisoftheaggregatetestdataandthemixvalidationtestdatashowsthatthe

    methylenebluetestisbestrelatedtostrippinginasphaltpavingmixtures.

    KEYWORDS:Hotmixasphalt,stripping,moisturedamage,plasticfines,fineaggregate,sandequivalent,plasticityindex,methyleneblue

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    SampleNumber

    PF-1

    PF-2

    PF-3

    PF-4

    PF-5

    PF-6

    PF-7

    PF-8

    PF-9

    PF-10

    Table1.FineAggregateTypesandLocation

    Description

    PitRunNaturalSand

    HighCalciumLimestone

    Dolomite

    Granite

    BlastFurnaceSlag

    Limerock

    Granitewith4%HighPlasticityClay

    Limerockwith3.4%HighPlasticityClay

    Granitewith2.6%HighPlasticityClay

    Limerockwith1%HighPlasticityClay

    Location

    Alabama

    Alabama

    Alabama

    Georgia

    Alabama

    Florida

    Georgia

    Florida

    Georgia

    Florida

    AggregateTestsandResults Thefollowingtestprocedureswereusedtotestthefineaggregates: AASHTOT176 PlasticFinesinGradedAggregatesandSoilsbyuseoftheSand

    (ASTM2419) EquivalentTest AASHTOT90 DeterminingthePlasticLimitandPlasticityIndexofSoils

    (ASTMD4318) OhioDOT MethyleneBlueValueofClays,MineralFillers,andFines

    SandEquivalentTest

    Thesandequivalenttestisusedtodeterminetherelativeproportionsofplasticfinesorclay-like

    materialinfineaggregates.Fineaggregatepassingthe4.75mm(No.4)sieveisplacedinagraduated,transparentcylinderwhichisfilledwithamixtureofwaterandaflocculatingagent.Afteragitationand20minutesofsettling,thesandseparatesfromtheclay-likefines,andtheheightsofsandandsandplusclayaremeasured.Thesandequivalentistheratiooftheheightofthesandtotheheightofsandplusclaytimes100.Highersandequivalentwillbeobtainedincaseofacleanerfineaggregate.MinimumspecifiedsandequivalentvaluesforfineaggregateinHMArangefrom26to60(5).Theminimumrequirementof45ismostcommon.TherequirementisalsobasedonthetypeofHMAcoursesuchasbaseandsurfacecourse.Thistesthastheadvantagesthatitisquicktoperform,requiresverysimpleequipmentwhichcanbeusedwithminimaltrainingorexperience,andhasgivenreasonablygoodresults.

    PlasticityIndex

    PlasticityIndexisbeingusedbyseveralagenciestomeasurethedegreeofplasticityoffines.

    PlasticityIndex(PI)isthedifferencebetweentheliquidlimitandtheplasticlimitofthematerialpassing425:m(No.40)sieve.ASTMD1073(StandardspecificationforFineAggregateinBituminousPavingMixtures)andD242(StandardSpecificationforMineralFillerforBituminousPavingMixtures)limitthePIofthisfractionpassingthe425 :m(No.40)sieve(includingthemineralfiller)toavalueof4orless.SomestatesspecifyamaximumPIfortheP200material.AreviewofliteratureindicatesnoreportedcorrelationbetweenthePIandthefieldperformanceofHMA.Precisiondatahavenotbeenestablishedforliquidlimitandplasticlimittestswhicharebasedonsubjectivejudgementandexperienceofthetester.

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    MethyleneBlueTest

    ThisFrenchtestmethodisrecommendedbytheInternationalSlurrySealAssociation(ISSA)to

    quantifytheamountofharmfulclaysofthesmectite(montmorillinite)group,organicmatterand

    ironhydroxidespresentinfineaggregate.Thetestmethodtitled"DeterminationofMethyleneBlueAdsorptionValue(MBV)ofMineralAggregateFillersandFines,"iscontainedinTechnicalBulletin145ofISSA(9).Theprincipleofthetestistoaddquantitiesofastandardaqueoussolutionofthedye(methyleneblue)toasampleuntiladsorptionofthedyeceases.

    ArepresentativesampleofdryfineaggregateisscreenedthroughtheNo.200sieve.Theportion

    ofthesamplepassingtheNo.200sieveistestedformethylenebluevalue(MBV).Tengramsofthesamplearedispersedin30gramsofdistilledwaterinabeaker.Onegramofmethyleneblue(MB)isdissolvedinenoughdistilledwater,toproduce200mlofsolution,sothat1mlofsolutioncontains5mgofmethyleneblue.ThisMBsolutionistitratedstepwisein0.5mlaliquotesfromtheburretteintothecontinuallystirredfineaggregatesuspension.AftereachadditionofMBsolutionandstirringforoneminute,asmalldropoftheaggregatesuspensionis

    removedwithaglassrodandplacedonafilterpaper.SuccessiveadditionsofMBsolutionarerepeateduntiltheendpointisreached.Initially,awell-definedcircleofMB-staineddustisformedandissurroundedwithanouterringorcoronaofclearwater.Theendpointisreachedwhenapermanentlightbluecolorationor"halo"isobservedinthisringofclearwater.TheMBvalueofaspecificfineaggregatefractionisreportedasmilligramsofmethylenebluepergramofspecificfineaggregatefractionsuchas:MBV=5.3mg/g,0/#200.TheMBVexpressesthequantityofMBrequiredtocoverthetotalsurfaceoftheclayfractionofthesamplewithamono-molecularlayeroftheMB.Therefore,theMBVisproportionaltotheproductoftheclaycontenttimesthespecificsurfaceoftheclay(10).Themethylenebluetestissimpleandpractical,anditscostisreasonable.AnOhioDOTversionofthetest(givenintheAppendix)wasusedinthisstudy.

    Table2summarizesmeasuredaggregateproperties.Eachtestwasrunintriplicateandaverage

    valuesarereported.Specificgravityandwaterabsorptionoffineaggregate(AASHTOT84)weredeterminedformixdesignpurposesonly.

    Table2.FineAggregateTestResults

    Mix# PF-1 PF-2 PF-3 PF-4 PF-5 PF-6 PF-7 PF-8 PF-9 PF-10Test Natural Lime- Dolo- Granite Blast Lime- Granite Limerock Granite Limerock

    Sand stone mite Furnace rock +4% +3.4% +2.6% +1%Slag Clay Clay Clay Clay

    SandEquivalent 24 90 91 58 87 84 39 63 51 74PlasticityIndex NP NP NP NP NP NP NP NP NP NP(Passing#40)PlasticityIndex 29 NP NP NP NP NP 40 40 40 40(Passing#200)

    MethyleneBlue 18.4 1.3 0.3 2.1 2 9.5 80.0 66.0 47.5 26.9ApparentSG. 2.667 2.744 2.869 2.750 2.711 2.678 2.730 2.672 2.823 2.676BulkSG. 2.558 2.665 2.786 2.657 1.623 2.358 2.651 2.363 2.743 2.360Water 2.0 1.1 1.1 1.3 1.2 5.1 - - - -Absorption

    AsshowninTable2,theplasticityindexforalloftheseaggregates,especiallythefractionpassing425:m(No.40)sieve,waszero(nonplastic),therefore,thetwomainaggregateteststhatwereusedforcomparativepurposeswerethesandequivalenttestandthemethylenebluetest.Asmentionedearlier,thesandequivalencemeasurestherelativeamountofclay-sizedparticlesinafineaggregate.Themethylenebluetestdeterminestheamountandnatureof

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    potentiallydetrimentalmaterial,suchasclayandorganicmaterial,thatmaybepresentina

    aggregate.

    MixtureTestsandResults

    ThegradationwasheldconstantforallmixesandisshowninFigure1.Allmixescontainedacommonlimestonecoarseaggregate(33%)butdifferentfineaggregates.Superpavevolumetricmixdesignwasusedtodeterminetheoptimumasphaltcontenttogive4%airvoidsformixwitheachfineaggregate.Themixdesigndatasuchasoptimumasphaltcontent,voidsinthetotalmix(VTM),andvoidsinthemineralaggregate(VMA)aregiveninTable3.

    Figure1.MixGradation

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    Table3.SuperpaveVolumetricMixDesignData

    OptimumAsphaltMixDesignation Content VTM VMA

    PF-1 5.5 4.0 14.2

    PF-2 5.3 4.0 15.8

    PF-3 3.9 4.0 11.9

    PF-4 5.2 4.0 14.4

    PF-5 6.8 4.0 15.2

    PF-6 8.0 4.0 20.6

    PF-7 5.2 4.0 14.4

    PF-8 8.0 4.0 20.6

    PF-9 5.2 4.0 14.4

    PF-10 8.0 4.0 20.6

    ThefollowingtwomixturevalidationtestswereusedtoevaluatethestrippingpotentialofHMAmixtures:

    AASHTOT283ResistanceofcompactedBituminousMixturetoMoistureInducedDamage

    HamburgWheel-TrackingDevice

    Ofallthetestmethodsavailableforevaluatingmoisturesusceptibility,AASHTOT283

    (modifiedLottmantest)ismorewidelyusedanditsreliabilityisconsideredrelativelybetterthannumerousothertestmethods(2).RecentfieldstudiesbyAschenbrener(8)indicatedthat

    AASHTOT283couldreasonablepredictthestrippingpotentialofColoradoaggregates.ThemoisturesusceptibilityoftheHMAmixturesisquantifiedintermsofretainedtensilestrengthafterwaterconditioning.

    TheHamburgwheel-trackingdevice(HWTD)wasusedforadditionalvalidation.Thisdevice

    hasbeenusedsuccesfullybytheCityofHamburg,Germany,theColoradoDepartmentofTransportation(8),andKochMaterialsCompany'slaboratoryinTerreHaute,Indianaforidentifyingaggregateswhicharesusceptibletomoisture-induceddamage.TheHWTDmeasuresthecombinedeffectsofruttingandmoisturedamagebyrollingasteelwheelbackandforthacrossthesurfaceofaHMAslabthatissubmergedinhotwater.TheHMAslabiscompactedinthelaboratorybyamechanicallyoperatedcompactorcalledalinearkneadingcompactor.Theslabmeasures320mminlength,260mminwidth,and80mmin

    thickness.Theslabweighsabout15kgandiscompactedtoavoidcontentof71percent.TheslabissecuredinareusablesteelcontainerwithplasterofParis.Theslabissubmergedinwaterwhichcanbeheatedfrom250C(770F)to700C(1580F),thestandardtestingtemperaturebeing50(122).

    Twoslabscanbetestedsimultaneouslywithtworeciprocatingsolidsteelwheels(diameter

    203.5mmandwidth47.0mm)loadedto710N.Thelengthoftravelis230mmandtheaveragespeedis1.1km/hourresultingin532passes/minute.

    Thetestingdurationis20,000cyclesanddeformationisrecordedandplottedaftereachcycle.

    Onthecyclesversusdeformationplottwodistinctlinesaregenerallyobserved.Thefirstline(ruttingline)indicatesruttingintheHMAunaffectedbystripping.Thefollowingsecondline

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    (strippingline)withasteeperslopeindicatesruttingduetostripping.Thepoint(numberof

    cycles)wheretheslopeoftheruttinglineandtheslopeofthestrippinglineintersectiscalledtheinflectionpoint.Thisisthepointwherestrippingisassumedtohavebeeninitiated.Inflectionpoint(expressedintermsofnumberofcycles)isthetestparameterofinterestforthisstudy.

    Table4containstheaveragespecimenvoidsinthetotalmix(VTM)andvoidsinthemineralaggregate(VMA)informationfortheslabsusedintheHamburgwheeltrackingtests.

    Table4.VTMandVMAforHamburgWheelTrackingSpecimens

    OptimumAsphaltMixDesignation

    PF-1

    PF-2

    PF-3

    PF-4

    PF-5PF-6

    PF-7

    PF-8

    PF-9

    PF-10

    Content

    5.5

    5.3

    3.9

    5.2

    6.88.0

    5.2

    8.0

    5.2

    8.0

    VTM

    6.0

    5.0

    7.1

    4.6

    5.45.0

    5.0

    5.8

    4.2

    5.0

    VMA

    16.0

    15.7

    14.9

    15.0

    15.621.6

    15.5

    22.2

    14.9

    21.5

    Table5containstheaveragespecimenVTMandVMAinformationforthespecimensusedintheAASHTOT283tests.MixesPF-6,PF-8,andPF-10usedFloridalimerockasthemainfineaggregate.MixesPF-8andPF-10onlydifferfromPF-6inthattheycontainadditionalamountsofclay.ThesethreemixeshaveveryhighVMAandhighoptimumasphaltcontent(Table3).

    Theonlycriteriausedtodeterminetheoptimumasphaltcontentofthesemixeswas4%VTM.Itisverylikelythatthislimerockdegradedexcessivelyinthegyratorycompactor.TheresultingdegradationwillincreasetheVMAofthemixthusrequiringanincreasedasphaltcontentinordertoachievetheproperVTM.Moreover,thelimerockishighlyabsorptiveand,therefore,requiredadditionalasphaltbinder.

    Table5.VTMandVMAforAASHTOT283Specimens

    MixDesignation ConditionedSpecimens UnconditionedSpecimens

    VTM VMA VTM VMA

    PF-1 6.9 16.8 6.9 16.8

    PF-2 7.2 17.7 7.4 17.9

    PF-3 7.0 14.7 7.0 14.8PF-4 7.0 17.1 7.0 17.1

    PF-5 7.3 17.3 7.2 17.2

    PF-6 7.4 23.6 7.3 23.5

    PF-7 7.4 17.6 7.3 17.6

    PF-8 7.1 23.3 7.1 23.2

    PF-9 8.0 18.3 8.4 18.6

    PF-10 6.5 23.0 6.5 22.8

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    Table6containsthemixturevalidationtestresults.

    Table6.MixtureValidationTestResults

    MixDesignation

    PF-1

    PF-2

    PF-3

    PF-4

    PF-5

    PF-6

    PF-7

    PF-8

    PF-9

    PF-10

    AsphaltContentat4%Voids

    5.5

    5.3

    3.9

    5.2

    6.8

    8.0

    5.2

    8.0

    5.2

    8.0

    TSRResults,%

    49.3

    85.0

    79.1

    61.3

    47.5

    62.0

    44.2

    48.4

    30.8

    49.0

    HamburgWheelTest(InflectionPoint)

    5000

    17000

    17500

    6800

    17000

    3800

    5500

    5200

    4300

    2400

    STATISTICALANALYSISOFTESTDATASinglevariablecorrelationanalysisandmultipleregressionanalysesweremadeusingaggregatetestvaluesasindependentvariablesandmixvalidationtestvaluesasdependentvariables.CorrelationmatricesweredevelopedusingtheSAScomputerprogramsothattherelationshipsbetweenaggregatetestsandHMAperformanceparameter(strippinginthiscase)couldbeexaminedinatabularform.Correlationcoefficients,thatis,Rvalueswereusedinthe

    correlationmatricestablesbecausetheirsign(+or-_indicatesthenatureoftherelationshipbetweenthevariables.Whenlinearequations(y=a+bx)areshown,coefficientsofdetermination,thatis,R2valueswereusedsincethesignofthe"b"coefficientwillindicatethenatureoftherelationshipbetweentheindependent(x)andthedependent(y)variables.

    TheforwardselectionmultiplevariablesproceduregivenintheSASprogramwasusedtoselect

    theaggregatetest(s)whichis(are)relatedtoHMAstripping.Theforwardselectionprocedurebeginsbyfindingthevariablethatproducestheoptimumone-variablesubset,thatis,thevariablewiththelargestcoefficientofdeterminationorR2.Inthesecondstep,theprocedurefindsthatvariablewhich,whenaddedtothealreadychosenvariable,resultsinthelargestincreaseinR2andsoon.TheprocesscontinuesuntilnovariableconsideredforadditiontothemodelprovidesanincreaseinR2consideredstatisticallysignificantatthespecificlevel(P=0.05forthisstudy).

    Table7containsacorrelationbetweentheaggregatetestsandmixvalidationtests.Inadditionto

    thecomparisontosandequivalent(SE)andmethyleneblue(MB),themixvalidationtestswerealsocomparedtovariationsoftheresultsofthesetwoaggregatetests,intheeventthattherelationshipsmaynotbelinear.Thevariationsusedinthecomparisonwerethelogofeachtestresult,thesquareofeachresult,andtheinverseofthesquareoftheresults.

    TheTSRisbestrelatedtologmethyleneblue(R=-0.79,P=0.006).Itscorrelationwiththesquare

    ofsandequivalenthasaR=0.67,.P=0.03.Inflectionpointisalsobestrelatedtologmethyleneblue(R=-0.82,P=0.03).ItscorrelationwiththesquareofsandequivalenthasR=0.69,P=0.03.

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    Table7.CorrelationBetweenAggregatePropertiesandMixPropertiesa

    AggregateTest

    SandEquivalentMethyleneBlue

    (SandEquivalent)2

    (MethyleneBlue)2

    Log(SandEquivalent)

    Log(MethyleneBlue)1/(SandEquivalent)2

    1/(MethyleneBlue)2

    TSR

    0.6150.06

    -0.6390.05

    0.6730.03

    -0.5020.14

    0.5250.12

    -0.7940.006

    -0.3160.37

    0.5380.11

    InflectionPoint

    0.6180.06

    -0.5520.098

    0.6860.03

    -0.3900.27

    0.5280.12

    -0.8250.003

    -0.3400.34

    0.5590.09

    aTopvaluesarecorrelationcoefficientsRandbottomvaluesaresignificancelevelsPineachcell.

    TheforwardselectionprocedureinSAScomputerprogramwasusedtodetermineifcombinationsofvariablescontainingmethyleneblueandsandequivalentvaluescouldimprovepredictionofTSRandinflectionpoint.Nocombinationwasfoundthatimprovedthe

    predictabilityoftherelationshipswithlogMBshowninTable8.TheforwardselectionproceduredidnotproceedbeyondSteponeafterselectingthemethylenebluetest.

    Figures2and3showtheplotsoflogmethyleneblueversusTSRandinflectionpoint,

    respectively.

    Table8.ResultsofForwardSelectionProcedure

    StepDependent Independent Model R2 PVariable Variable

    1 TSR Log TSR=70.277-6.84(LogMethylene 0.63 0.006

    Methylene Blue)Blue

    1 Inflection Log InflectionPoint=14104.2-2644.4(Log 0.68 0.003Point Methylene MethyleneBlue)

    Blue

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    Figure2.MethyleneBluevs.TSR

    Figure3.MethyleneBluevs.InflectionPoint

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    CONCLUSIONS

    BothTSRandinflectionpointtestdataindicatethatmethyleneblueisthefineaggregatetestwhichisbestrelatedtostrippingofHMA.Therefore,themethylenebluetestisrecommendedto

    indicatethepresenceofdetrimentalplasticfineswhichmayinducestrippinginHMAmixtures.REFERENCES1.

    2.

    3.4.5.

    6.

    7.

    8.

    9.

    10.

    Stuart,KD,"EvaluationofProceduresUsedtoPredictMoistureDamageinAsphaltMixtures,"FHWA,ReportFHWA/RD-86/091,1986.Kandhal,P.S.,"MoistureSusceptibilityofHMAMixes:IdentificationofProblemandRecommendedSolutions,"NationalAsphaltPavementAssociation,QualityImprovementPublication119,December1992.Balghunaim,F.,"ImprovingtheAdhesionCharacteristicsofBituminousMixesbyWashingDustContaminatedCoarseAggregates,"paperpresentedtotheTransportationResearchBoard,1990.Hveem,F.N.,:"SandEquivalentTestforControlofMaterialsDuringConstruction,"Proceedings,HighwayResearchBoard,Vol.32,1953.O'Hara,W.G.,"EvaluationoftheCaliforniaSand-EquivalentTest,"Proceedings,.HighwayResearchBoard,Vol.34,1955.Clough,R.H.,andMartinez,J.E.,"ResearchonBituminousPavementsUsingtheSandEquivalentTest,"HighwayResearchBoard,Bulleting300,1961.Kandhal,P.S.,"EvaluationofBaghouseFinesinBituminousPavingMixtures,"JournaloftheAssociationofAsphaltPavingTechnologists,Vol.50,1981.Aschenbrener,T.,"ComparisonofColoradoComponentHotMixAsphaltMaterialswithSomeEuropeanSpecifications,"ColoradoDepartmentofTransportation,ReportNo.CDOT-DTD-R-92-14,December1992.InternationalSlurrySealAssociation,"TestMethodforDeterminationofMethylene

    BlueAbsorptionValue(MBV)ofMineralAggregateFillersandFines,"ISSABulleting145,1989.Hosking,R.,"RoadAggregatesandSkidding,"TransportationResearchLaboratory,State-of-the-ArtReview4,HMSO,London,1992.

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    AppendixA

    StandardMethodofTestforMethyleneBlueValueofClays,MineralFillers,andFines

    1.Scope

    1.1Thisstandardprovidesproceduresfordeterminingtheamountofpotentiallyharmfulfinematerial(includingclayandorganicmaterial)presentinanaggregate.

    1.2ThevaluesstatedinS1unitsaretoberegardedasthestandard.

    1.3Thisstandardmayinvolvehazardousmaterials,operations,andequipment.This

    standarddoesnotpurporttoaddressallofthesafetyproblemsassociatedwithitsuse.Itistheresponsibilityoftheuserofthisproceduretoestablishappropriatesafetyand

    healthpracticesandtodeterminetheapplicabilityofregulatorylimitationspriortouse.

    2.SummaryofTest

    2.1MethyleneBluesolutionistitratedintodistilledwatercontainingthesamplematerial

    (passing75mmsieve)inincrements.AsmallamountofwatercontainingthesamplematerialandtitratedMethyleneBlueisremovedviaaglassrodanddroppedontofilterpaper.WhenthesampleaggregatecannolongerabsorbmoreMethyleneBlue,ablueringisformedonthefilterpaper.

    3.SignificanceandUse

    3.1TheMethyleneBlueValuedeterminedbythisstandardcanbeusedtoestimatetheamountofharmfulclaysandorganicmatterpresentinanaggregate.AlargevalueforMethyleneBlueValueindicatesalargeamountofclayororganicmaterialpresentinthesample.

    4.Apparatus

    4.1Ambercoloredburetteofatleast50mlcapacity4.2MagneticMixerwithstirbar

    4.3Balancesensitiveto0.01g

    4.4Glassrodofapproximately250mmlengthandapproximately8mmdiameter

    4.5Timerorstopwatch

    4.6Sieve(75mm)andpan

    4.7VolumetricFlaskof1000mlcapacity

    4.8WhatmanNo.2filterpaper

    4.9Glassbeakers

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    4.10 MethyleneBlue,reagentgrade-datedandstoredfornomorethanfourmonthsin

    abrownbottlewrappedwithfoilinadarkcabinetatlabtemperature.

    4.11 Distilledwateratlabtemperature

    5.Sampling

    5.1Arepresentativesampleofthefineaggregatetobetestedisdriedtoconstantweightandscreenedthroughthe75mm(No.200)sieve.Theportionpassingthroughthesieve(P200material)isretainedfortesting;therestisdiscarded.

    6.Procedure

    6.1Weightout10.0g(+/-0.05g)oftheP200materialthathasbeendriedtoconstant

    weightandplaceinbeaker.

    6.2Add30gofdistilledwaterandstirwiththemixeruntiltheP200materialisuniformly

    dispersed.

    6.3OnegramofMethyleneBlueisdissolvedinenoughdistilledwatertoproduce200ml

    ofsolution,witheach1mlofsolutioncontain5mgofMethyleneBlue.

    6.4Withtheslurrystillmixing,filltheburettewiththeMethyleneBluesolution,add0.5

    mlofthesolutiontotheslurry,andstirforoneminute.

    6.5Removeadropoftheslurry,usingtheglassstirringrod,andplaceonthefilerpaper.

    6.6Observetheappearanceofthedroponthefilterpaper.Theendpointisindicatedby

    theformationofalightbluehaloaroundthedrop.ContinueaddingtheMethylene

    Bluesolutiontotheslurryin0.5mlincrementswith1minutestirringaftereachaddition,thentesting,untiltheendpointisreached.

    6.7Aftertheendpointisreached,continuestirringfor5minutesandretest.

    Note:Withexperience,thepersonperformingthetestcanreachtheendpointmorequicklybyskippingearlyincrements.

    7.Calculation

    7.1MBV=CV/W

    where:

    MBV=MethyleneBlueValueinmgofsolutionpergoftheP200material

    C=mgofMethyleneBlue/mlofsolutionV=mlofMethyleneBluesolutionrequiredfortitrationW=gramsofdrymaterial

    7.2ThecalculationsmaybesimplifiedbyinsertingthemgofMethyleneBluepermlof

    solutionandthegramsofdrymaterial.

    MBV=(5xV)/10

    MBV=0.5V

    12

  • 8/9/2019 Tests for Plastic Fines in Aggregates Related to Stripping in Asphalt Paving Mixtures

    17/17

    Kandhal,Lynn,&Parker

    8.PrecisionandBias

    8.1Precision-Noprecisionhasbeenestablishedforthistest.

    8.2Bias-Nobiascanbeestablishedbecausenoreferencematerialisavailableforthistest.

    13


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