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CHARACTERIZATION OF ASPHALT BINDER EXTRACTED FROM RECLAIMED ASPHALT SHINGLES By J. Richard Willis, Ph.D. Pamela Turner January 2016
Transcript
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CHARACTERIZATIONOFASPHALTBINDEREXTRACTEDFROMRECLAIMEDASPHALT

SHINGLES

ByJ.RichardWillis,Ph.D.

PamelaTurner

January2016

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CHARACTERIZATIONOFASPHALTBINDEREXTRACTEDFROMRECLAIMEDASPHALTSHINGLES

By

J.RichardWillis,Ph.D.PamelaTurner

NationalCenterforAsphaltTechnologyAuburnUniversity,Auburn,Alabama

January2016

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DISCLAIMER

Thecontentsof this reportreflect theviewsof theauthorswhoareresponsible for the factsandaccuracyofthedatapresentedherein.Thecontentsdonotnecessarilyreflecttheofficialviews or policies of the sponsored agency, the National Center for Asphalt Technology, orAuburn University. This report does not constitute a standard, specification, or regulation.Commentscontainedinthisreportrelatedtospecifictestingequipmentandmaterialsshouldnotbeconsideredanendorsementofanycommercialproductorservice;nosuchendorsementisintendedorimplied.

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1. Report No. NCAT Report 16-01

2. Government Accession No.

3. Recipient's Catalog No.

4. Title and Subtitle CHARACTERIZATION OF ASPHALT BINDER EXTRACTED FROM RECLAIMED ASPHALT SHINGLES

5. Report Date January 2016

6. Performing Organization Code

7. Author(s) J. Richard Willis, Ph.D. and Pamela Turner

8. Performing Organization Report No.

9. Performing Organization Name and Address National Center for Asphalt Technology 277 Technology Parkway Auburn, AL 36849

10. Work Unit No. (TRAIS) 11. Contract or Grant No. G00007328

12. Sponsoring Agency Name and Address Federal Highway Administration 1200 New Jersey Avenue, SE Washington, DC 20590

13. Type of Report and Period Covered Final Report 2013-2015

14. Sponsoring Agency Code

15. Supplementary Notes FHWA Contracting Officer’s Representation: Christopher Wagner

16. Abstract An 80% increase in the amount of RAS used in asphalt mixtures was reported from 2009 to 2012. Despite this increase, there is still little guidance given on the characterization of RAS binder in AASHTO MP 023 and PP 078. In addition to the lack of direction, many contractors and owner agencies do not have equipment capable of determining the actual high and low temperature performance grades of the RAS binder; therefore, work needs to be completed which can aid owner agencies and contractors in determining the true PG grades of RAS binder. While a common virgin binder is PG 64 – 22, RAS binders are much stiffer with critical high temperature grades between 140 and 180°C and critical low temperature grades between 0 and 40°C. If this stiffer binder is not considered in design, it can negatively influence fatigue and thermal cracking performance. The objective of this research is to investigate methods of characterizing RAS asphalt binder for both the critical high and low temperatures. Binder was extracted from RAS and tested to determine the true (or measured) PG grade of the binder. In addition to direct measurement, extrapolation methods were assessed to determine appropriateness in case equipment was not available for direct measurement. Finally, within sample and between sample testing variability was quantified for RAS binders using conventional testing methodology. These tests were completed on RAS samples from across the U.S. and included both post-consumer (PC) and manufacturers’ waste (MW) RAS. Ultimately, it was determined that one could extrapolate the critical high temperature grade of RAS binders ensuring that variability and outliers were considered in the analysis; however, less repeatable and reliable results were discovered when assessing critical low temperatures.

17. Key Words SHINGLE, BINDER, VARAIBILITY, PERFORMANCE GRADE

18. Distribution Statement No restriction. This document is available at www.ncat.us.

19. Security Classif. (of this report) Unclassified

20. Security Classif. (of this page) Unclassified

21. No. of Pages 39

22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized

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TABLEOFCONTENTSTABLE OF CONTENTS ................................................................................................................ 51 Introduction ................................................................................................................................. 6

1.1 Background ....................................................................................................................... 61.2 Objectives and Scope ........................................................................................................ 7

2 Literature Review ........................................................................................................................ 82.1 RAS Asphalt Binder ....................................................................................................... 10

3 Materials and Test Methods ...................................................................................................... 123.1 Materials ......................................................................................................................... 123.2 Test Methods ................................................................................................................... 12

4 Test Results ............................................................................................................................... 184.1 RAS Binder Critical High Temperature Grade ............................................................... 184.2 RAS Binder Critical Low Temperature Grade ............................................................... 26

5 Conclusions and Recommendations ......................................................................................... 326 References ................................................................................................................................. 33Appendix A High temperature test results ............................................................................... 35Appendix B High temperature Extrapolations ......................................................................... 38

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1 INTRODUCTION 1.1 BackgroundEngineersbeganusingreclaimedasphaltshingles(RAS)inpavementmixturesasanalternateasphaltsourceinthe1980sand1990s(1).WhenpolymermodificationofasphaltbindersbecamemorecommonintheSuperpavePerformanceGrading(PG)specifications,practitionersbegantosearchforwaystoreduceasphaltbindercostwhilestillreceivingthedesiredlevelofperformance.Thisencouragedtheasphaltpavementindustrytouserecycledproductssuchasreclaimedasphaltpavement(RAP),groundtirerubber(GTR),andRASintheirmixtures.WhileproductslikeGTRserveasanasphaltmodifierbyeasingtheindustry’sdependenceonthesupplyofpolymers(suchasstyrene-butadiene-styrene),RAPallowscontractorstoreplacebothaggregateandasphaltbinderwhileRASallowscontractorstoreplaceasphalt(primarily).Agency,industry,andacademiahaveworkeddiligentlyandsuccessfullytosuccessfullyincreaseRAPpercentagesonanationalbasis.SuccessfulRASutilizationisstilldevelopingandistheprimaryreasonforthisreport.Nearly11milliontonsofwasteshinglesareproducedeachyear,resultinginapproximately22millioncubicyardsofwastematerialneedingtobelandfilled(2).Environmentalstandardshaveevolvedsincethe1980s,forcingdisposalsitestoeithercloseorlimittheamountofasphaltshinglestheycanaccept.Between1980and1997,morethan11,000RASdisposalsitesclosed,causingtippingfeestoescalatetonear$100perton(1,3,4).Asphaltshinglesaccountforapproximately8to10percentoftheannualbuilding-relatedwasteandconstructiondebrisproducedintheU.S.annuallyandisthethirdlargestbuildingwastematerialintheworld(5).Inadditiontoreducingthebuildingwaste,usingjustonetonofRAStoreplaceaggregateandasphaltinanewmixturecanreducethecarbonfootprintoftheasphaltpavingindustryby55tonsofcarbon(6)Thus,usingRASinasphaltmixtures,ineffect,reducesboththefiscalandenvironmentalcostsofasphaltpavementbeingproduced.RAShasalsobeenshowntoimprovetheperformanceofasphaltmixturesintermsofrutresistance,stability,andhightemperaturesusceptibility(7);however,theimproperuseofRAS(i.e.eitherusingtoomuch,toocoarseagrind(sizeofshingle),ornotusingsoftPGasphalt)hasbeenshowntocauseprematurefailuresinsomepavements.An80%increaseintheamountofRASusedinasphaltmixtureswasreportedfrom2009to2012(8).Despitethisincrease,thereisstilllittleguidancegivenonthecharacterizationofRASbinderinAASHTOMP023andPP078.Inadditiontothelackofdirection,manycontractorsandowneragenciesdonothaveequipmentcapableofdeterminingtheactualhighandlowtemperatureperformancegradesoftheRASbinder;therefore,workneedstobecompletedwhichcanaidowneragenciesandcontractorsindeterminingthetruePGgradesofRASbinder.WhileacommonvirginbinderisPG64–22,RASbindersaremuchstifferwithcriticalhightemperaturegradesbetween140and180°Candcriticallowtemperaturegradesbetween0

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and40°C.Ifthisstifferbinderisnotconsideredindesign,itcannegativelyinfluencefatigueandthermalcrackingperformance. 1.2 ObjectivesandScopeTheobjectiveofthisresearchistoinvestigatemethodsofcharacterizingRASasphaltbinderforboththecriticalhighandlowtemperatures.BinderwasextractedfromRASandtestedtodeterminethetrue(ormeasured)PGgradeofthebinder.Inadditiontodirectmeasurement,extrapolationmethodswereassessedtodetermineappropriatenessincaseequipmentwasnotavailablefordirectmeasurement.Finally,withinsampleandbetweensampletestingvariabilitywasquantifiedforRASbindersusingconventionaltestingmethodology.ThesetestswerecompletedonRASsamplesfromacrosstheU.S.andincludedbothpost-consumer(PC)andmanufacturers’waste(MW)RAS.

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2 LITERATUREREVIEWAsphaltroofingmaterialsincludecompositionshingles,built-uproofing,andtorchdownroofing(apolymer-modifiedasphaltmembranestrengthenedwithfabricsandcommonlyusedonflatroofs).Themajorcomponentsofasphaltroofingwasteincludeasphalt,mineralfillerandgranules,glassfibermatting,organicpaperfelt,andnails.Thereareanumberofpotentialendusagesforasphaltroofingwaste,includingasphaltmixtures,whichiscurrentlythelargestmarketforRAS(9).Asphaltshinglescontainatleasttwoproductsneededinasphaltmixtureproduction:asphaltbinderandfinecrushedaggregate.Theyalsoproducefibers(10-20%byweight)thatmaybeusefulincertaintypesofasphaltmixtures.RAScontainsapproximately19to36%asphaltbinderbyweight.Inaddition,thegranulesintheshingles(approximately20-38%byweight)areasourceofaggregateusedinasphaltpavementmixtures.Anumberoflaboratoryandfield-scaleresearchstudieshavebeenconductedtoevaluatetheuseofasphaltshinglesinhotmixasphalt(HMA)andstonematrixasphalt(SMA).Someofthesebenefitsincludethefollowing(10):

• Reduceddemandforvirginasphaltbinderandaggregate,• SignificantreductiontopurchasedMFforSMAmixtures,• Improvedresistancetoruttingduetothereinforcementprovidedbyfiberscontainedin

shingles,and• ReducedproductioncostofHMA.

TheasphaltbinderinRASdecreasesthedemandforvirginasphaltcementandprovidesseveralbenefitstoboththeindustryandstateagencies.First,recycledbinderfromRASreducesthecostoftheasphaltbinderneededdependingonthestateand/orsource.Wastefromshinglefactoriescanbeprocessedandimmediatelybeaddedtothehotmixasphaltprocessorrenewedwithrejuvenatingchemicalspriortothemixprocess.Secondly,asphaltmixturesrequirespecificaggregategradationswithspecificdurabilityproperties.ThemineralorceramicaggregateinRASprovidesasourceoffineaggregateandreducesthedemandforvirginaggregate;however,thisreductionofaggregateissmall.Finally,certainpropertiesofasphaltpavementhavebeenshowntoimprovewiththeadditionofrecycledasphaltshingles.Theseincluderuttingresistance(11).Whilethecompositionofshinglesvariesdependingonthemanufacturerandroofingapplication,mostarecomposedoffourbasicmaterials:asphaltcement,feltorfiber,mineralorceramicaggregate,andmineralfiller.Organicorfiberglassfeltbackingsformthebasicstructureforshingles.Theorganicfeltistypicallycomposedofeithercelluloseorwoodfibersandisdesignedtosupporttheasphaltandaggregategranules.Fiberglassbackingsaremanufacturedbymixingfineglasswithwaterintheformofaglasspulpthatisthenformedintoafiberglasssheet(12,13).Thebackingisthensaturatedwithasphaltcement.

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Shingleasphaltsare“airblown,”whichincreasestheirstiffnesswhenusedinasphaltmixturescomparedtoconventionalpavingasphalt.Theyarefurtherstabilizedwithafiller(70%passingthe#200sieve)(10,14).Asecondapplicationof“airblown”asphaltisappliedasacoveringforbothsidesoftheshingle.Thetopsideoftheshingleisthencoveredwithgranulesdesignedtoprotecttheasphaltfromboththesun’sultravioletraysandphysicaldamageduetoabrasiononrooftops.Mostshinglemanufacturersuseacombinationofcrushedrockscoatedwithceramicmetaloxidesasgranules.Additionalheadlapgranulescanbeusedinthisapplication.Bothaggregategranulesareidealforroofingshinglesduetotheiruniformsize,toughness,andangularshapes(13).Insomecases,chemicalsarealsoaddedtotheaggregatetopreventalgaegrowth(14).Shinglesarefinishedwithadustingoffinesandtothebacksurfacetopreventtheagglomerationoftheshinglesthatcouldoccurduringtransportation.AschematicofthefinalproductisshowninFigure1.Table1presentsestimatesofthepercentageofeachmaterialinorganicandfiberglassshingles.

Figure1Schematicofasphaltshinglecomposition(10).Table1CompositionofShingles(14,15,16)Component OrganicFelt FiberglassMatAsphaltCement 30-36% 19-22%Felt(Fiber) 2-15% 2-15%MineralAggregate 20-38% 20-38%MineralFiller 8-40% 8-40%Justastherearedifferencesbetweenorganicandfiberglassshingles,therearealsodifferencesinthematerialcompositionbasedonshinglesource.LossofaggregateparticlesinthePCshinglesgenerallycauseshigherasphaltcontentthantheMWshingles.ExposuretocontaminantsalsocausesPCshinglestocontainmoredeleteriousmaterialsthanMWshinglessuchaspaper,wood,andnails.Whilemanyofthesecontaminantsareremovedduringthegrindingprocess,furtherremovalofdeleteriousmaterialsmaybenecessarybeforeRAScanbeusedinasphaltmixtures(13).

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AnunderstandingofeachcomponentinRASandhowitcancontributetoanasphaltmixtureisessential.PCshinglestockpilestendtoexhibitmorevariabilitythanMWshinglesinsize,aggregategradation,andasphaltcontentaswellasmaterialpropertiessuchasspecificgravity.Shingletype,manufacturer,andagecansignificantlyinfluencethesefactors(17).Currently,PCRASisusedmorefrequentlythanMWRASbecausethereis10timestheamountofPCshinglesavailableforuse.2.1 RASAsphaltBinderThedesiretouseRASinasphaltmixturesstemsfromtheabilitytosubstantiallyreducetheoverallmaterialcostbyreplacingvirginasphaltbinderwithreclaimedasphaltinapavementmixture.Inorderforthistobecost-effective,theasphaltcontentoftheRASformixtureproportioninganditsperformancegrade(PG)mustbequantifiedtoensuremixtureperformance.SinceRASasphalthavebeenairblown,theyareinherentlystifferthanvirginormodifiedasphaltsandhavedifferentrheologicalproperties.Thisstiffnesscausesmanystateagenciestobeconcernedaboutlong-termdurabilityofmixturescontainingRASinrelationshiptocrackingandstripping.(3,18,19).Oneexampleofthiswasseenatthe2012NCATTestTrack,intestsectionsdesignedfortheFloridaDepartmentofTransportation.TwocomparativesectionsweredesignedusingPG76-22basebinders.Thefirstsectionhad20percentRAPwithoutanyRAS,andthesecondsectioncontained20percentRAPwithanadditional5percentRAS.ThesectionwhichincludedRAShadsignificantlymorelowseveritytop-downcrackingthantheRAPonlysection(20).ThemostcommontoolforassessingasphaltbinderstodayisAASHTOM320,StandardSpecificationforPerformanceGradeBinderGrading.ManystatesdonotrequiretheRASbindertobeperformancegradedduetothedifficultyinhandlingandtesting.Inordertousehighershingleorbinderreplacements,AASHTOPP78,DesignConsiderationsWhenUsingReclaimedAsphaltShingles(RAS)inAsphaltMixtures,requiresuserstoknowthePGoftheRASbindertocompleteblendingchartsusedtodeterminethecorrectvirginbindergradetobeusedinthemixdesign.Despitepotentialhandlingandtestingdifficulties,itisimportantthatblendedRASasphaltandvirginbindermeetsthesameperformancecriterionasvirginbinderintermsofbindergrade,strength,anddurability(21).ThePerformanceGradeofRASbindersisdeterminedusingAASHTOM320onmaterialsthathavebeenextractedusingmethodspreviouslymentionedandthenrecoveredusingASTMD5404.Inthecurrentperformancegradingsystem,thestiffnessandelasticitypropertiesoftheasphaltbinderareevaluatedatthreeaginglevels.First,theoriginal,unagedbinderisassessed.Second,theasphaltbinderundergoesasimulatedshort-termagingintherollingthinfilmoven(RTFO)beforebeingassessedagain.Thefinalassessmentoccursafterasimulatedlong-termaginginthepressureagingvessel(PAV).CurrentmixdesignandbindergradingspecificationsdonotrequireRAPbinderstoundergolong-termagingsincetheyhavealreadybeenagedinthefield,buttheydoundergoshort-termaging.

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WhilethisprovisionisgivenforRAPbinders,nosuchguidanceisprovidedforRASbinders.Itisknownthatairblowingduringshingleproductionincreasesthebinderviscosity.ThebinderofPCshinglesisfurtheragedwhiletheshingleisactingasaroofingmaterial.Still,researchershavepresentedresultsusingboththeRTFOandPAVagingprocedures(21).AgencieshavereporteddifficultyworkingwithrecoveredRASbindersduetotheirextremestiffnessatnormalbinderhandlingtemperaturesandthesmallmoldshapesrequiredforsomebindertesting(21).Additionally,commonDSRmodelsusingwaterbathsfortemperaturecontrolcannotbeusedtodirectlyassessthehightemperaturegradeoftheRASbindersincemanyRASbindershavecriticalhightemperaturesabovetheboilingpointofwater(18).Inmanycases,RASbindersalsoaredifficulttotestforcriticallowtemperatures,asthebindersmustproceedbelow-36°Ctoreachthecriticallowtemperaturestiffnessbuthavem-valuesthatwillonlypassattemperaturesgreaterthan0°C(18).ThisdifferenceinlowtemperaturefailurevaluesindicatesthatrecoveredRASbindersareextremelybrittle,makingthecreationoftestspecimensforlowtemperaturetestingdifficult.AgencieshavereportedusingcheesegraterstoshredRASbindersoitcouldbePGgraded(22).ExampleperformancegradesofshinglebindersarepresentedinTable2toshowthedifficultiesandextremecriticaltemperaturesdeterminedwhenassessingRASbinders.Whilethislistofbindergradesisnotexhaustive,onecommonlyseesthatPCRASbinderismuchstifferthanMWRASbinderwhenreviewinglowPGgradesfortheRAS.Table2RASPGGradesReference Location RASType HighPG LowPG23 Oregon MW 134 NA18 Wisconsin MW 124-154 0>22 Missouri MW 143+ 0>24 Minnesota MW 134-153.9 (-12.7)to(-6.1)24 Minnesota PC 121.2–133.1 (-6.9)to(10.6)NCAT Alabama PC 175.4 41.7NCAT Alabama MW 132.6–137.2 (-18.6)to(-13.0)

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3 MATERIALSANDTESTMETHODS3.1 MaterialsSixRASsampleswereobtainedtoevaluatethehightemperatureperformanceofRASbinder,andfourweresuppliedforlowtemperatureevaluation(Table3).ThesesamplesweresenttoNCATfromcontractorswhovolunteeredtoprovidematerial.Someofthesampleswerenotlargeenoughtoconductthefullsuiteoftesting;therefore,thesampleswereeitherusedforhightemperatureorlowtemperaturetesting.TheresearchteamtriedtoreceivesamplesfromdifferentgeographicregionsofthecountrythatcommonlyuseRASaswellassamplesfrombothPCandWMshingletypes.ThesameofRASfromOregonwasablendofbothPCandMWRASinsteadofjustasingleRASsource.Table3RASSamples

State ShingleType TemperatureTestingMW PC High Low

Michigan ü ü ü ü

Oregon ü ü ü üNewHampshire ü ü ü

Georgia ü ü Texas ü ü ü

Wisconsin ü ü3.2 TestMethods 3.2.1 ExtractionandRecovery AsphaltbinderwasextractedandrecoveredfromeachRASsourceusingthecentrifugeextractionmethod(ASTMD2172-05MethodA)withTrichloroethylene(TCE)asthesolvent.Othersolventsareusedbyotheragencies,andtheAsphaltInstituteiscurrentlyconductingsomeworktocomparetheeffectsofusingdifferentsolventsonRASbindertestingresults.SomestatesdonotuseTCEasasolventbecauseofthelimitedavailabilityandenvironmentalconcernsassociatedwithitsuse.Therotaryevaporatorrecoveryprocedure(ASTMD5404-03)wasusedtoremovethesolventfromtheextractedbinder.DuetothehighviscosityoftherecoveredRASbinder,itwasnecessarytoincreasethedraintimeandtemperatureusedforremovingtherecoveredbinderfromtherecoveryflask.Forthistesting,atotaldraintimeof30minutesatatemperatureofapproximately190°CwasusedwhichmightcauseRASstiffeningatthispointoftesting.Threeextraction/recoveryprocedureswereperformedforeachRASsourcewiththerecoveredbindersfromeachprocedurebeingstoredinseparatecontainersforhightemperaturetesting.Afourthextraction/recoveryprocedurewasperformedforeachRASsourcetoobtainrecoveredbinderforlowtemperaturetesting.

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3.2.2 BinderTestingMethodsTherecoveredRASbindersweretestedinaccordancewiththeproceduresdescribedinAASHTOM320-10,AASHTOR29-08,andAASHTOD7643-10todeterminehighandlowperformancegradesandcontinuousgradingtemperatures.TruegradingtemperaturesasdescribedinASTMD7643-10aredefinedasthetemperatureatwhichatestcriterionismet(forexample,thecontinuousgradingtemperatureforRTFO-agedmaterialtestedintheDSRisthetemperatureatwhichG*/sin(δ)=2.20kPa)andareusuallydeterminedbyinterpolatingbetweenapassingandfailingtestresult.ThereisnoofficialguidancegivenregardingagingofrecoveredbindersexceptforAASHTOM323-13,AppendixX1,StandardSpecificationforSuperpaveVolumetricMixDesign,whichstatesthattherecoveredbinderfromRAPshouldonlybeshort-termagedintheRollingThinFilmOven(RTFO)priortotesting.AnattemptatagingrecoveredRASbinderintheRTFOshowedthattheviscosityoftheRASbinderwastoohighandthatitdidnotmoveinthebottlesduringtheprocedure.Therefore,theRASbindersforthisstudyweretestedintheiras-recoveredstatewithnoadditionalaging.ShorttermandlongtermagingofRASbindersintheRTFOorPAVisconsideredredundantduetothepreviousagingofinservicePCshinglesandtheagingduetotheairblownprocessofallshingles.Thesemanufacturingandin-situagingconditionsaremoreseverethantheRTFOandPAV.ThehightemperaturepropertiesoftheRASbindersweremeasuredasdescribedinAASHTOT315-08usingaTAInstrumentsAR2000EXmodelDynamicShearRheometer(DSR).ThisDSRmodelhasthecapabilityoftestingattemperaturesupto150°Cusingaheatedupperplateassembly.Fortemperatureshigherthan150°C,anenvironmentaltemperaturechamberassemblywithaliquidnitrogenpurgewasused.TheDSRprocedureisperformedusinga25-mmdiameterparallelplategeometrywitha1000micronsamplegap.Asinusoidalshearloadisappliedtothetestspecimenatafrequencyof10rad/secandatargetangularstrainlevelof10%todeterminecomplexshearmodulus(G*)andphaseangle(δ).Forcriteriapurposes,therecoveredRASbinderwastestedasRTFO-agedmaterial,eventhoughnoagingwasperformed.ThetemperaturesnecessarytoachieveafailinghightemperatureresultforrecoveredRASbindertypicallyexceedthetemperaturerangeofmanyDSRmodels.Thisresultsintheneedtoextrapolateby50–60°Cormoretodeterminethecontinuousgradingtemperature.Toaddresstheissueofextrapolationoversuchawidetemperaturerangeanditseffectoncontinuousgradedetermination,twomethodswereusedtocalculatethehighcontinuousgradingtemperatureoftheRASbinders.Onesetofsamplesfromeachindividualextractionwastestedat82,88,and94°C,thehigheststandardtesttemperaturesthatawatercontrolledDSRshouldbeabletomaintain.TheresultingvaluesofG*/sin(δ)wereplottedversustemperatureonalogscaleandextrapolatedtoavalueof2.20kPa.ThesecondsetofsampleswastestedatelevatedtemperaturescorrespondingtopassingandfailingvaluesofG*/sin(δ)andthecontinuousgradingtemperaturecalculatedbyinterpolatingbetweenthetworesultsusingtheequationsprovidedinASTMD7643-10.

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LowcontinuousgradingtemperaturesweredeterminedfortherecoveredRASbinderusingtwotestprocedures.TheBendingBeamRheometer(BBR)procedureasdescribedinAASHTOT313-12measureslowtemperaturestiffnessandrelaxationpropertiesusingthinbeamsofasphaltbindertowhicha980mNcreeploadisappliedfor240seconds.Thestiffnessparameter,S(t),iscalculatedbasedonthemeasureddeflectionofthebeamduringtheloadingperiod.Therelaxationparameter,m(t),iscalculatedastheslopeoftheS(t)curveattimet.ContinuousgradingtemperaturesforlowtemperaturetestingaredefinedasthetemperaturesatwhichS(60sec)=300Mpaandm(60sec)=0.300,withthewarmerofthetwotemperatureschosenasthecontinuousgrade.TestingrecoveredRASbinderintheBBRpresentedsomechallengesthatmadeitdifficulttoobtainreliableresults.ThehighviscosityoftherecoveredRASbinderincombinationwiththesmalldimensionsoftheBBRsamplemold(6.35-mmx12.70-mmx127-mm)madepreparingtestspecimensdifficult,asthebinderdidnotflowintothemoldsevenly.TheRASbindertendedtocoolandstiffenbeforereachingthebottomofthemold,leavinggapsinthetestspecimen.Inadditiontothedifficultywithpreparingthetestspecimens,thebehavioroftherecoveredRASbinderatthetesttemperaturestypicallyusedintheBBR(below0°C)prohibitedtestingattemperaturesthatbracketthelowtemperaturepass/failcriteria.Atlowtemperatures,recoveredRASbinderhasverypoorrelaxationpropertiesandtypicallyfailsthem(60sec)criteriaatthewarmesttemperaturethattheBBRbathcanreliablymaintain(+6°C).Thelowtemperaturestiffnessvaluesrequiretestingatmuchcoldertemperaturesthanwhatthem(60sec)requirestoachieveafailingtestresultbasedontheS(60sec)criteria.ThepoorrelaxationpropertiesoftheRASbindersmakethetestspecimensbrittleatcoldertemperaturesandpronetobreakagewhenthetestloadisapplied.Sincethem-valueisthecontrollingcriteriaforRASbinders(itscontinuousgradetemperatureishigherthanthecontinuousgradetemperatureforthestiffnesscriteriaandisusedtodeterminethelowPGgradeofthebinder),testingwasperformedatthetwowarmeststandardtesttemperaturespossible:+6and0°C.ThetestresultswerethenextrapolatedtovaluesofS(60)=300Mpaandm(60)=0.300todeterminethelowcontinuousgradingtemperaturesbasedontheBBRcriteria.ThelowcontinuousgradingtemperaturesoftherecoveredRASbindersweredeterminedusingaproceduredevelopedbyWesternResearchInstitute(WRI).The4-mmplateDSRprocedureprovidesamethodforestimatingBBRS(t)andm(t)valuesthateliminatestheneedtomoldtestspecimensandallowsfortestingatwarmertemperaturesthancanbeachievedintheBBRbath.Theprocedureuses4-mmdiameterDSRtestspecimentodeterminevaluesofstoragemodulus(G’(t))overarangeoffrequenciesfrom0.1–100rad/secat0.1%angularstrain(chosentobewithinthelinearregionforthebindersbeingtested).Thefrequencysweepswereperformedattwotemperatures(4and14°Cforthisresearch)andtheresultingisothermswereshiftedusingtheChristensen-Andersonmodeltocreateamastercurveatachosenreferencetemperature.Oncethemastercurvewascreated,G’(t)andtheslopeofthecurveat60seconds,mg’,werecalculatedbyfittingaquadraticpolynomialfunctiontothemastercurve.Equations1and2(developedbyWRI)werethenusedtoconverttheDSRdatatoBBRresultsatthereferencetemperature(25).

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S(t)=21.380+1.718*G’(t (1)m=-0.115*+0.708*mg’ (2)ThecalculationswererepeatedatmultiplereferencetemperaturesandtheresultingS(60)andm(60)valueswereusedtodeterminethelowcontinuousgradingtemperaturesoftherecoveredRASbinders.3.2.3 TestingVariabilityAnalysis ForeachRASsource,threetypesofvariabilitywereconsidered:

• Withinsample–howrepeatablearetestresultsobtainedfrommultipletestspecimentakenfromthesameextraction/recoveryprocedure,

• Betweensample–howreproduciblearetestresultsobtainedfromtestspecimenofthesameRASbindertakenfromdifferentextraction/recoveryprocedures,and

• Testorcalculationmethod–howdodifferentmethodsofdeterminingthesamecriteriaaffectthetestresults.

Table4showsasampletestingmatrixforoneRASbindersource.Table4SampleTestingMatrix

HighTemperature LowTemperature

Extraction Measured Extrapolated BBR 4-mm1 Test1 Test1 Test1 Test1

Test2 Test2 Test2 Test2Test3 Test3 Test3 Test3

2 Test1 Test1 Test1 Test1

Test2 Test2 Test2 Test2Test3 Test3 Test3 Test3

3 Test1 Test1 Test1 Test1

Test2 Test2 Test2 Test2 Test3 Test3 Test3 Test3

EachcellinTable4representsthreereplicatetestresultstoallowfordeterminationofwithinsamplevariability.StatisticalanalysiswasperformedonthereplicateresultsfromeachtestproceduretodeterminewhetherornottheresultsobtainedfromasinglesampleofRASbinderwererepeatable.Iftheresultswerenotrepeatable,thiscouldimplythateithertheRASbinderitselfwasnotahomogenousmaterialorthatitwassensitivetosomeportionofthehandlingortestingprocedures.

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BetweensamplevariabilityforthehightemperaturetestswasevaluatedbyrepeatingthetestproceduresonthreeseparatesamplesofthesamerecoveredRASbinder.Thiswasdonetoevaluateiftheextraction/recoveryprocedurecouldproducerecoveredRASbinderthathadconsistent,reproducibletestresults.Duetotimeandsamplequantitylimitations,betweensamplevariabilityatcoldtemperatureswasnotevaluated.Statisticalcomparisonswerealsoperformedtodeterminetheeffectofthedifferentmethodsofdetermininghighandlowcontinuousgradetemperatures.Forthehightemperatureresults,acomparisonwasmadebetweenthecontinuousgradetemperaturesdeterminedbyextrapolationandthoseobtainedbytestingatpassingandfailingtemperatures.Forthelowtemperatureresults,acomparisonwasmadebetweentheBBRcontinuousgradingtemperaturesandthoseobtainedfromthe4-mmDSRprocedure.3.2.4 HighTemperaturePredictionThetemperaturesnecessarytoachieveafailinghightemperatureresultforRASbindersfrequentlyexceedthetemperaturerangeofsomeDSRmodels,particularlythosethatuseawaterbathfortemperaturecontrol.Becauseofthis,itisoftennecessarytoextrapolateby50–60°Cormoretodeterminethecontinuousgradingtemperature.TwomethodswereusedtocalculatethehighcontinuousgradingtemperatureoftheRASbinders,andtheresultswerecomparedtodeterminewhateffect,ifany,thedifferenceintestprocedurehadonthecontinuousgradetemperatureresults.

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Figure2ExtrapolatedHighContinuousGradeExtrapolationThesecondsetofsampleswastestedatelevatedtemperaturescorrespondingtopassingandfailingvaluesofG*/sin(δ)andthecontinuousgradingtemperaturecalculatedbyinterpolatingbetweenthetworesults.

1.0

10.0

100.0

1000.0

60.0 80.0 100.0 120.0 140.0 160.0

G*/sinδ

,kPa

Temperature,°C

4-extrapolated

2.20

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4 TESTRESULTSSevenRASsamplesweredeliveredtoNCATforevaluation.Thischapterdescribestheevaluationofthosesamplesforbothcriticalhighandlowtemperatures.4.1 RASBinderCriticalHighTemperatureGrade 4.1.1 DeterminingCriticalHighTemperatureGradeandVariabilityThecriticalhightemperaturegradeofsixRASsampleswasdeterminedusingthepreviouslydescribedmethodology.ThreeofthesamplestestedwerePCRASwhiletwosampleswerefromMWRASstockpiles.ThefinalsamplewasablendofPCandMWRASusedinOregon.OncetheRASbinderhadbeenextracted,thecriticalhightemperaturegradeofeachRASsamplewasdeterminedonthreereplicatesfromthreeseparateextractionsforeachsample.ThisresultedinnineindividualtestpointsforeachRASsample.Table5providesthemeasuredtestresultsfromeachRASsample.IndividualtestresultsaregivenintheAppendixA.Itshouldbenotedthatthesetestresultsandconclusionsarebasedonlimitedtestresultsusingverychallengingtestingprocedures.Whencomparingthevariabilityofthehightemperaturetestresults,Table5showsthatasexpected,thewithinextractionvariabilitywaslowerthanthevariabilityoftheentiredataset.Eightofthe18extractionshadcoefficientsofvariation(COV)lessthan1%,whilesixhadCOVslessthan2%.WhencomparingthecoefficientsofvariationfortheentiredatasetofasingularRASsource,theCOVsrangedfrom3.2to7.7%.Thestandarddeviationsweresimilar.Tenoftheextractionshadstandarddeviationsoftriplicatemeasurementslessthan2°C.Sixextractionshadstandarddeviationsgreaterthan4°C.Thesinglelargeststandarddeviationforasingleextractionwas11.7°C.However,whencomparingthestandarddeviationsofthreereplicatesforthreeextractions,thedataweremorevariable.Standarddeviationsrangedfrom4.6to12°C. ThestatisticsshowthatMWRASwascommonlylessvariablethanPCRAS;however,theonesamplewiththeleastvariabilitybetweenextractionswastheMW/PCRASblendfromOregon.Whentryingtoestablish95%confidenceintervalsforthestandarddeviationsofthewithinextractionandbetweenextractiondatasets,Figures3and4showthatwhilethebetweendatasetisnormalbytheAnderson-DarlingNormalityTest(p=0.328),thewithinextractionstandarddeviationsarenotnormal.Whentransposedonalogscale(Figure5),however,thedatabecomesnormal,andonecanascertaina95percentconfidenceinterval.Therefore,usingthesetwo95percentconfidenceintervals,onemightexpectthestandarddeviationforthetestingofRASbinderbetweentwodifferentsamplestobe4.4and10.3°C.TheexpectedrangefortestingthehightemperaturegradeofRASbinderwithinsingleextractionswouldbe0.9to2.4°C.

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Table5HighTemperatureTestResults

State Michigan Texas Oregon MichiganNew

Hampshire Georgia

Source MW MWMW/PCBlend PC PC PC

Extract1

Average 135.4 126.6 143.8 160 159.8 148.2StandardDeviation 2 0.2 1.2 1.7 3.7 2.8CoefficientofVariation 1.5 0.2 0.9 1 2.3 1.9

Extract2

Average 133.1 137.4 146 161.7 163.8 151.1StandardDeviation 2.1 3.1 1 0.4 2.2 0.8CoefficientofVariation 1.6 2.3 0.7 0.2 1.3 0.6

Extract3

Average 144.7 131.7 151.9 144.4 145.4 170.3StandardDeviation 0.5 1.8 5.6 0.8 0.6 11.7CoefficientofVariation 0.4 1.4 3.7 0.6 0.4 6.8

Setof9Tests

Average 137.7 131.9 147.2 155.4 156.3 156.5StandardDeviation 5.5 5 4.6 8.3 8.7 12CoefficientofVariation 4 3.8 3.2 5.4 5.6 7.7

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Figure3BetweenExtractionStandardDeviationNormalityTestResults

Figure4WithinExtractionStandardDeviationNormalityResults

1stQuartile 4.9000Median 6.90003rdQuartile 9.5250Maximum 12.0000

4.3502 10.3498

4.7429 10.8214

1.7843 7.0108

A-Squared 0.35P-Value 0.328

Mean 7.3500StDev 2.8585Variance 8.1710Skewness 0.818897Kurtosis -0.262603N 6

Minimum 4.6000

Anderson-Darling NormalityTest

95% ConfidenceIntervalforMean

95% ConfidenceIntervalforMedian

95% ConfidenceIntervalforStDev

121086

Median

Mean

10864

95%ConfidenceIntervals

SummaryReportforBetween

1stQuartile 0.7500Median 1.75003rdQuartile 2.8750Maximum 11.7000

0.9994 3.6895

0.8000 2.4892

2.0296 4.0548

A-Squared 1.79P-Value < 0.005

Mean 2.3444StDev 2.7047Variance 7.3156Skewness 2.72845Kurtosis 8.68264N 18

Minimum 0.2000

Anderson-Darling NormalityTest

95% ConfidenceIntervalforMean

95% ConfidenceIntervalforMedian

95% ConfidenceIntervalforStDev

121086420

Median

Mean

4.03.53.02.52.01.51.0

95%ConfidenceIntervals

SummaryReportforWithin

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Figure5Log(within)StandardDeviationNormalityTests4.1.2 ExtrapolatingCriticalHighTemperatureGradeAsshownintheprevioustables,allsixRASsourceshadcriticalhightemperaturegradesgreaterthan100°C.DSRsusingwater-controlledtemperaturebathscannotachievereliabletemperaturesfortestinggreaterthanapproximately94°Cbeforeproblemssuchaswaterboilingbegintooccur.Therefore,inorderforagenciesandcontractorsusingwater-controlledtemperaturebathstodeterminecriticalhightemperaturegradesofRASbinder,anextrapolationmethodologyneedstobedetermined.ThesimplestmethodofextrapolatingthesedatawouldbetousealinearmodeltoplotG*/sinδat82,88,and94°C,andthencalculatethetemperaturewherethedatameetthecriticalhightemperaturecriterion.Thismethodologyisdescribedpreviouslyinmoredetail.Table6providestheextrapolatedhightemperatureresultsforallthreereplicatetestsofeachextraction.AppendixBshowstheindividualtestresults.

1stQuartile -0.12814Median 0.242863rdQuartile 0.45821Maximum 1.06819

-0.04664 0.38442

-0.09691 0.39291

0.32523 0.64975

A-Squared 0.14P-Value 0.972

Mean 0.16889StDev 0.43341Variance 0.18785Skewness 0.008242Kurtosis 0.103291N 18

Minimum -0.69897

Anderson-Darling NormalityTest

95% ConfidenceIntervalforMean

95% ConfidenceIntervalforMedian

95% ConfidenceIntervalforStDev

0.80.4-0.0-0.4

Median

Mean

0.40.30.20.10.0-0.1

95%ConfidenceIntervals

SummaryReportforLog (within)

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Table6HighTemperatureExtrapolations

State Michigan Texas Oregon MichiganNew

Hampshire Georgia

Source MW MWMW/PCBlend PC PC PC

Extract1

Average 136.3 137.2 145.5 150.9 141.3 137.2StandardDeviation 6.2 0.9 6.5 23.5 25.4 0.9CoefficientofVariation 4.55 0.6 4.5 15.6 17.9 0.6

Extract2

Average 131.1 137.5 139.3 192.0 146.1 137.5StandardDeviation 2.8 1.8 0.6 43.1 1.7 1.8CoefficientofVariation 2.15 1.3 0.5 22.4 1.2 1.3

Extract3

Average 131.1 198.5 148.1 160.5 147.2 198.5StandardDeviation 2.2 53.1 1.1 23.8 4.0 53.1CoefficientofVariation 1.50 26.8 0.7 14.9 2.7 26.8

Setof9Tests

Average 132.9 157.7 144.3 167.8 144.9 157.7StandardDeviation 4.4 40.5 5.1 33 13.1 40.5CoefficientofVariation 3.29 25.68 3.56 19.68 9.08 25.68

ItisnoteworthythatwhenconsideringwithinextractionCOV,fiveoftheRASsampleshadCOVsfortwoextractionsatlessthan3percent,whilethethirdRASextractionhadasignificantlylargerCOV.InmostcaseswheretheCOVwassignificantlylarger,onlyonetestresultcausedtheskewinthedata.TheonlyRASsamplethathadwithinextractionCOVsconsistentlygreaterthan14percentwastheMichiganPCRASwheretherewereconsistentdifferencesbetweenallthreeextrapolations.Whileoneshouldconsidervariabilityintheextrapolations,oneultimatelyneedstoknowiftheextrapolationsareaccuratecomparedtogivenmeasureddata.Tostatisticallyassessthesedata,pairedt-tests(α=0.05)wereusedvalidatethenullhypothesisofnodifferencebetweenthemeasuredandextrapolatedcriticalhightemperatures.ThistestwasconductedontheninetestresultsforeachRASsampleaswellastheentirepopulationoftests.P-valesarepresentedinTable7andshownostatisticaldifferencesbetweenthemeasuredandextrapolateddataforanyofthesixsamplesaswellastheentirepopulation.ThesepreliminaryresultswerebasedononlysixdifferentRASsamples.AdditionaltestingistakingplaceaspartofNationalCooperativeHighwayResearchProject9-55todetermineifthesetrendscontinuebeforemoredefinitiveconclusionsaredrawn.

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Table7StatisticalAnalysisofExtrapolatedtoMeasuredCriticalHighTemperaturesSample Michigan

MWMichiganPC

OregonBlend

NewHampshirePC

GeorgiaPC

TexasMW

Population

p-value 0.078 0.194 0.178 0.077 0.906 0.095 0.766Despitethelackofevidenceshowingstatisticaldifferences,scatterplotscomparingthemeasuredtoextrapolatedhightemperaturesshowdisagreementbetweenthemeasuredandextrapolateddata(Figure6).Furtherevidenceisgivenbythehistogramofthedifferencesbetweenthemeasuredandextrapolateddata(Figure7).Thoughmanyoftheresultsarewithinafewdegreesofeachother,numerousresultsstillshowerrorsintheextrapolationofmorethan15°Conapointtopointbasisshowingthatsinglereplicateextrapolationcanleadtoerrorincriticalhightemperatureexpectations.

Figure6DifferencesbetweenMeasuredandExtrapolatedData

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Figure7HistogramofMeasuredMinusExtrapolatedCriticalHighTemperatureBetteragreementisfoundwhencomparingtheaveragesoftriplicatetestingonasingleextraction.Thescatterplot(Figure8)showsthatmuchofthevariabilityseenfromindividualtestingisremoved,andthemajorityofthetestresultsaremorecomparablebetweenthedatasets.However,whenassessingthehistogramofthedifferences(Figure9),sixoftheeighteendatacomparisonshavedifferencesgreaterthan10°C,showingthatfurthertestingmayberequiredtoremovevariabilityfromtheanalysis.Someofthistestingiscurrentlyunderway.Thestatisticalanalysesmaybeslightlyskewedbythelimitedtestresults.

75604530150-15-30

25

20

15

10

5

0

Measured- Extrapolated,C

Freq

uenc

yH istogramofDifferences

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Figure8ComparisonofMeasuredandExtrapolatedDataofTriplicateTesting

Figure9HistogramofDifferencesbetweenMeasuredandExtrapolatedCriticalHighTemperatureAverageofTriplicateTestingfromSingleExtraction

20100-10-20-30

6

5

4

3

2

1

0

Measured- ExtrapolatedAveragefromTriplicateTesting,C

Freq

uenc

y

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Similarresultsareseenwhencomparingtheaveragesoftriplicatedatafromthreeseparateextractions.Approximately1/3ofthevarianceshavedifferencesgreaterthan10°C.Therefore,usingtheresultsofthisstudy,oneshouldextrapolatedatainordertoascertainacriticalhightemperaturegradeforRASbinder,runningtriplicatetestsfromasingleextractionandremovingobviousoutlierswouldbethemostappropriatemethod.Theslighterrorsfromtheextrapolatedresultswouldhavelittleeffectonchoosingavirginbinder.TheRASbindershaveacriticalhightemparound120Cto180°C.Thisismuchhotterthanapavementwillseeinitslife.Thecriticaltemperatureisimportantbecauseitwillaffectthefinalblendedbindercriticalhighandlowtemps. 4.2 RASBinderCriticalLowTemperatureGrade ThetwolowtemperaturetestingmethodsdescribedinthemethodologywereusedtodeterminecriticallowtemperaturesforfourRASsources(TexasMW,WisconsinMW,OregonBlend,andNewHampshirePC).ThepurposeofthisportionofthetestingwastodetermineiftheDSRmethodcouldgivecriticallowtemperaturescomparabletothoseobtainedfromtheBBRmethod.Asecondaryreasonforthetestingwastodetermineifonemethodcouldprovidebetterrepeatabilitythantheother.OnlyoneextractionprocedurewasperformedforeachRASsourceduetomaterialandtimelimitations.Usingtherecoveredbinder,threereplicatetestswereperformedforboththeBBRtestandthe4-mmdiameterDSRtest.TheresultsfromeachofthesetestswereusedtocalculatecriticallowtemperaturesbasedontheS(60)andm(60)criteria.ThisresultedinadatasetoftwelvecriticallowtemperaturesforeachRASsource(threepertest/criteriacombination).Itshouldbenotedthatthesetestresultsandconclusionsarebasedonlimitedtestresultsusingverychallengingtestingprocedures. 4.2.1 DeterminingCriticalLowTemperatureGradeUsingBendingBeamRheometerTables8and9showtheBBRS(60)andm(60)criticallowtemperaturesforeachRASsource.Ascanbeseenfromthetables,theresultsbasedontheBBRtestfollowtypicalcriticallowtemperaturetrendsfortheMWRASsourceswiththevaluescalculatedusingtheBBRm(60)criteriabeingwarmerthanthevaluescalculatedusingtheBBRS(60)criteria.TheOregonBlendedRASalsofollowedthistrendfortwoofthethreereplicates,whilethePCRASonlyfolloweditforoneofthethreereplicates.

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Table8CriticalLowTemperaturesBasedonBBRS(60)CriteriaReplicate TXMW WIMW ORBlend NHPC1 -67.7 -31.5 -36.7 -42.62 -39.4 -26.0 -33.0 -72.23 -35.1 -32.8 -25.7 -26.0Average -47.4 -30.1 -31.8 -46.9StandardDeviation 17.7 3.6 5.6 23.4COV,% 37.3 12.1 17.6 49.9Table9CriticalLowTemperaturesBasedonBBRm(60)CriteriaReplicate TXMW WIMW ORBlend NHPC1 -3.3 2.5 -28.9 -118.02 -9.3 -3.5 -44.5 -64.03 -9.1 -2.3 21.3 14.3Average -7.2 -1.1 -17.3 -55.9StandardDeviation 3.4 3.2 34.4 66.5COV,% 46.7 293.4 198.3 119.0BothsetsofBBRcriticallowtemperatureshadhighvariabilitywithCOVvaluesrangingfrom12.1-293%.AlthoughtheCOVvaluesfortheBBRS(60)resultsappearedtobelowerthantheCOVvaluesfortheBBRm(60)results,apairedt-testanalysis(α=0.05)showedthattherewasnostatisticaldifferencebetweenthevariabilityforthetwocriteria(p=0.087).Inthisanalysisthem(60)andS(60)criteriawerepairedfromasingularRASsource.Standarddeviationsrangedfrom3.6-23.4°CfortheBBRS(60)criticallowtemperaturesand3.2-66.5°CfortheBBRm(60)criticallowtemperatures.Apairedt-testanalysis(α=0.05)showedthattherewasnostatisticaldifferencebetweenthestandarddeviationsforthetwosetsofdata(p=0.401).ThisanalysiswascompletedsimilarlytothepreviouslymentionedCOVanalyses.4.2.1 DeterminingCriticalLowTemperatureGradeUsingDynamicShearRheometerTables10and11showtheS(60)andm(60)criticallowtemperaturescalculatedusingthetestresultsfromthe4-mmdiameterplateDSRprocedure.TheDSRcriticallowtemperaturesalsofollowedtypicaltrendswiththeDSRm(60)criteriahavingwarmercriticaltemperaturesthanthosecalculatedusingtheDSRS(60)criteriaforallfourRASsources.COVvaluesfortheDSRcriticallowtemperaturesrangedfrom40-163.7%fortheDSRS(60)resultsandfrom32.7-147.7%fortheDSRm(60)results.Standarddeviationsforbothcriteriawerehigh,rangingfrom25.1°C-70.4°CfortheDSRS(60)criticallowtemperaturesandfrom10.5°C-35.8°CfortheDSRm(60)criticallowtemperatures.Pairedt-testanalysis(α=0.05)showednostatisticaldifference

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ineitherCOVorstandarddeviationbetweenthetwocriteria(COVp-value=0.927,Standarddeviationp-value=0.133).Table10CriticalLowTemperaturesBasedonDSRS(60)CriteriaReplicate TXMW WIMW ORBlend NHPC1 -58.9 -12.0 -61.5 -74.72 -87.4 -11.6 -102.3 -26.83 -132.7 -55.3 34.8 -18.8Average -93.0 -26.3 -43.0 -40.1StandardDeviation 37.2 25.1 70.4 30.2COV,% 40.0 95.5 163.7 75.4Table11CriticalLowTemperaturesBasedonDSRm(60)CriteriaReplicate TXMW WIMW ORBlend NHPC1 -25.8 -14.0 -32.9 -50.02 -31.0 5.0 -68.6 -7.93 -47.6 -12.4 2.9 -12.3Average -34.8 -7.1 -32.9 -23.4StandardDeviation 11.4 10.5 35.8 23.1COV,% 32.7 147.7 108.8 98.94.2.3ComparisonofBBRandDSRCriticalLowTemperatureResultsTostatisticallycomparethecriticallowtemperaturesresultsobtainedfromtheBBRtothoseobtainedusingtheDSR,pairedt-tests(α=0.05)wereusedwiththenullhypothesisofnodifferencebetweenthecriticallowtemperaturevalues.SeparateanalysesweredonecomparingtheS(60)andm(60)criticallowtemperaturesforeachRASsample.Acomparisonforeachcriterionwasalsocompletedusingtheentirepopulationoftests.P-valesarepresentedinTables12and13.Table12StatisticalAnalysisofBBRS(60)toDSRS(60)CriticalLowTemperaturesSample TexasMW WisconsinMW OregonBlend NewHampshirePC Populationp-value 0.128 0.820 0.809 0.774 0.425Table13StatisticalAnalysisofBBRm(60)toDSRm(60)CriticalLowTemperaturesSample TexasMW WisconsinMW OregonBlend NewHampshirePC Populationp-value 0.016 0.396 0.617 0.469 0.752TheresultsshownostatisticaldifferencescouldbefoundbetweenthemeasuredandextrapolatedresultsforalmostalltheRASsamplesaswellastheentirepopulation.Theonlyexceptionwasthem(60)criticallowtemperaturesfortheTexasMWRASsource.

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Despitethelackofevidenceshowingstatisticaldifferences,scatterplotscomparingtheBBRtoDSRcriticallowtemperaturesshowalackofcorrelationbetweenthetwomethodsforeithercriteria(Figures10-13).Furtherevidenceofthislackofagreementisgivenbythehistogramofthedifferencesbetweentheresults.Thoughsomeresultsarewithinafewdegreesofeachother,mostresultsshowdifferencesbetweenthetestmethodsofmorethan25°Conapointtopointbasiswhichwouldmakethesedifferencesbeconsideredpracticalinnature.ThisindicatesthatthereisnotgoodagreementbetweentheDSRandBBRmethodsfortheseRASsamples.DuetothecomplexnatureRASbinders,itisdifficulttodeterminewhichtestresultprovidesthemostaccuratetestresult.

Figure 10 Comparison of BBR S(60) and DSR S(60)

y=0.4679x-32.333R²=0.02432

-160.0

-120.0

-80.0

-40.0

0.0

40.0

80.0

-160.0 -120.0 -80.0 -40.0 0.0 40.0 80.0

DSRS(60)Low

Cric

calTem

perature,°C

BBRS(60)LowCriccalTemperature,°C

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1007550250-25-50

3.0

2.5

2.0

1.5

1.0

0.5

0.0

BBR S(60) - DSR S(60)

Freq

uenc

yHistogram of S(60) Differences

Figure11HistogramofS(60)Differences

Figure12ComparisonofBBRm(60)andDSRm(60)

y=0.3033x-18.366R²=0.27715

-160.0

-120.0

-80.0

-40.0

0.0

40.0

80.0

-160.0 -120.0 -80.0 -40.0 0.0 40.0 80.0DSRm(60)Low

Cric

calTem

perature,°C

BBRm(60)LowCriccalTemperature,°C

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50250-25-50-75

6

5

4

3

2

1

0

BBR m(60) - DSR m(60)

Freq

uenc

yHistogram of m(60) Differences

Figure13ComparisonofBBRm(60)andDSRm(60)Pairedt-testanalyses(α=0.05)wereusedtoevaluatetheCOVvaluesandthestandarddeviationbetweenthetwotestmethods.TheDSRandBBRtestmethodswerefoundtohavestatisticallythesameCOVvalues(p=0.971)andstandarddeviations(p=0.315).Basedontheseresults,itwouldappearthatthe4-mmDSRtest,whilesimplertorunmaynotprovidecriticallowtemperaturesthatareequivalenttothoseobtainedfromtheBBRprocedureforthissetofRASsamples.TheDSRprocedurealsodoesnotappeartoprovidemorerepeatableresultsthantheBBRprocedure.

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5 CONCLUSIONSANDRECOMMENDATIONS BasedonthelimitedstudywhichevaluatedvarioustestingandextrapolationmethodsfordeterminingRASbinderproperties,thefollowingconclusionsweredrawn:

• WithinsamplecriticalhightemperaturegradeswerelessvariablethanbetweensamplecriticalhightemperaturegradesforagivenRASsource.Onewouldexpecttheresultsofthreecriticalhightemperaturestovarybetween0.9and2.4°CforagivenRASsource.Thestandarddeviationsforbetweensampletestsrangedfrom4.6to12°C.

• Linearlyextrapolatedcriticalbinderhightemperaturegradeswerestatisticallythesameastestedresults;however,scatterplotsshowedpracticaldifferenceswereevidentwithinthedataset.Usingaveragesoftriplicatetestresultsreducedvariabilityanddisagreement.

• BothDSRandBBRlowtemperaturetestingprovidedvariableandinconsistentcriticallowtemperaturesforRASbinder.

Basedontheseconclusions,thefollowingrecommendationscanbemade:

• OnecanextrapolatecriticalhightemperaturesofRASbinder;however,careshouldbetakentoreducevariability.Removeoutliersandtakeatleastanaverageoftriplicateresultstoensuremorepreciseandaccurateresults.

• BoththeBBRandDSRarevariableandprovideresultswhichmaynotbeaccurateforascertainingthecriticallowtemperaturegradeofRASbinder.Additionalworkneedstobecompletedonthissubject.AnewtestingmethodmaybeneededfordeterminingthelowtemperaturepropertiesofRASbinder.

• OthermethodsshouldbeconsideredforextrapolationofcriticalhighandlowtemperaturegradesforRASbinders.Currently,theAsphaltInstituteisworkingondevelopingandquantifyingthevariabilityofotherextrapolation/blendingmethodsusingthesamematerialsusedinthisstudy.

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6 REFERENCES

1. Davis, J. “Roofing the Road – Using Asphalt Shingles as Binder.” Asphalt Magazine,http://www.asphaltmagazine.com–October2009,AccessedMarch13,2012.

2. Flynn,L.“RoofintMaterialsHoldPromiseforPavements,”RoadsandBridges,1993.3. Krivit,D.“RASinHMA:UnderstandingofValueGrows,”http://www.cdworldmag.com,

March2010,AccessedMarch12,2012.4. Bauman,A.“AsphaltShingleRecyclinginMassachusetts,”greenGoatFactSheet,2005.5. BioCycle.“AnalyzingWhat’sRecyclableinC&DDebris,”p.53,2003.6. Caulfield, M. “Asphalt Shingles in Paving,” SolidWaste Association of North America

Meeting,2010.7. C&DRecyclingProgram.“AsphaltRoofingShinglesinAsphaltPavement,”2005.8. Hansen, K. and A. Copeland. Annual Asphalt Pavement Industry Survey on Recycled

Materials and Warm-Mix Asphalt Usage: 2009-2013. National Asphalt PavementAssociation,InformationSeries138,2014.

9. VanDam,T.,J.Harvey,S.Muench,K.Smith,M.Snyder,I.Al-Qadi,H.Ozer,J.Meijer,P.Ram,J.Roesler,andA.Kendall.TowardSustainablePavements:AReferenceDocument.FHWA-HIF-15-002.FederalHighwayAdministration,2015.

10. Townsend, T., J. Powell, and C. Xu. “Environmental Issues Associated with AsphaltShingleRecycling,”ConstructionMaterialsRecyclingAssociation,October2007.

11. Zhang, F. “Framework for BuildingDesign Recyclability,”Masters Thesis,University ofKansas,2011.

12. Blachford, S.L. and T. Gale. “Shingle: How Products are Made,”http://science.enotes.com,2002.

13. Grodinsky,C.,N.Plunkett,andJ.Surwilo.PerformanceofRecycledAsphaltShinglesforRoadApplications,FinalReport,2002.

14. 3MCorporation.ScotchguardAlgaeResistantRoofingSystem.http://solutions.3m.com,2007.

15. Lee.R.“RecycledShinglesinHMA,”Presentedatthe2009SEAUPGConference,HiltonHeadIsland,SouthCarolina,2009.

16. NAHB.“FromRoofstoRoads:RecyclingAsphaltRoofingShinglesintoPavingMaterials.”http://www.epa.gov,1998.

17. Foo, K.Y., D.L. Hanson, and T.A. Lynn. “Evaluation of Roofing Shingles in Hot MixAsphalt,”JournalofMaterialsinCivilEngineering,Vol.11,No.1,pp.15-20,1999.

18. Bonaquist, R. Effect of Recovered Binders from Recycled Shingles and Increased RAPPercentagesonResultantBinderPG,SPR#0092-10-06,December2011.

19. Cascione, A., R.C. Williams, S. Gillen, D.S. Haugen. “Utilization of Post ConsumerRecycled Asphalt Shingles and Fractionated Recycled Asphalt Pavement in Hot MixAsphalt,” Proceedings of the 2010 Mid-Continent Transportation Research Forum,Madison,Wisconsin,August2010.

20. Willis,J.R.,A.Taylor,andT.Nash.“LaboratoryandFieldEvaluationofFloridaMixturesat the 2012 NCAT Test Track,” 95th Annual Meeting of the Transportation ResearchBoardCompendiumofPapers,2016.

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21. Newcomb, D., M. Stroup-Gardiner, B. Weikle, and A. Drescher. Influence of RoofingShinglesonAsphaltConcreteMixtureProperties.FinalReport,MN/RC-93/09,MinnesotaDepartmentofTransportation,St.Paul,MN,June1993.

22. Schroer, J. “Missouri’s Use of Recycled Asphalt Shingles (RAS) in Hot Mix Asphalt,”Proceedingsofthe2009Mid-ContinentTransportationResearchSymposium,2009.

23. Scholz,T.V.“Preliminary InvestigationofRAPandRAS inHMAC,”FinalReportSR500-291,OregonDepartmentofTransportation,February2010.

24. McGraw,J.“IncorporationofRecycledAsphaltShinglesinHot-MixedAsphaltPavementMixtures,” Final Report #2010-08, Minnesota Department of Transportation, March2010.

25. Sui,C.,M.J.Farrar,P.M.Harnsberger,andW.H.Tuminello,“ANewLow-TemperaturePerformanceGradingMethod:using4mmParallel-platesonaDynamicShearRheometer,”TransportationResearchRecord2207,TransportationResearchBoard,NationalResearchCouncil,Washington,D.C.,2011.

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APPENDIXA HIGHTEMPERATURETESTRESULTSTableA-1MichiganMWRASMeasuredCriticalHighTemperatureGradeReplicate MeasuredCriticalHighTemperature,°C

Extraction1 Extraction2 Extraction31 137.6 130.7 144.32 133.8 133.8 144.53 134.7 134.7 145.3Average 135.4 133.1 144.7StandardDeviation 2.0 2.1 0.5COV,% 1.5 1.6 0.4AverageofNineTests 137.7StandardDeviationofNineTests 5.5COVofNineTests,% 4.0TableA-2MichiganPCRASMeasuredCriticalHighTemperatureGradeReplicate MeasuredCriticalHighTemperature,°C

Extraction1 Extraction2 Extraction31 161.6 161.8 144.12 158.3 162.0 145.33 160.2 161.3 143.7Average 160.0 161.7 144.4StandardDeviation 1.7 0.4 0.8COV,% 1.0 0.2 0.6AverageofNineTests 155.4StandardDeviationofNineTests 8.3COVofNineTests,% 5.4TableA-3OregonRASBlendMeasuredCriticalHighTemperatureGradeReplicate MeasuredCriticalHighTemperature,°C

Extraction1 Extraction2 Extraction31 142.4 144.9 145.62 144.3 146.2 156.43 144.7 146.9 153.6Average 143.8 146.0 151.9StandardDeviation 1.2 1.0 5.6COV,% 0.9 0.7 3.7AverageofNineTests 147.2StandardDeviationofNineTests 4.6COVofNineTests,% 3.2

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TableA-4NewHampshirePCRASMeasuredCriticalHighTemperatureGradeReplicate MeasuredCriticalHighTemperature,°C

Extraction1 Extraction2 Extraction31 164.1 166.1 145.62 158.1 161.9 144.73 157.3 163.4 145.8Average 159.8 163.8 145.4StandardDeviation 3.7 2.2 0.6COV,% 2.3 1.3 0.4AverageofNineTests 156.3StandardDeviationofNineTests 8.7COVofNineTests,% 5.6TableA-5GeorgiaPCRASMeasuredCriticalHighTemperatureGradeReplicate MeasuredCriticalHighTemperature,°C

Extraction1 Extraction2 Extraction31 151.5 152.0 161.92 146.6 150.3 165.43 146.6 150.9 183.7Average 148.2 151.1 170.3StandardDeviation 2.8 0.8 11.7COV,% 1.9 0.6 6.8AverageofNineTests 156.5StandardDeviationofNineTests 12.0COVofNineTests,% 7.7

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TableA-6TexasMWRASMeasuredCriticalHighTemperatureGradeReplicate MeasuredCriticalHighTemperature,°C

Extraction1 Extraction2 Extraction31 126.7 133.9 133.82 126.4 138.4 131.03 126.8 139.9 130.4Average 126.6 137.4 131.7StandardDeviation 0.2 3.1 1.8COV,% 0.2 2.3 1.4AverageofNineTests 131.9StandardDeviationofNineTests 5.0COVofNineTests,% 3.8

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APPENDIXB HIGHTEMPERATUREEXTRAPOLATIONSTableB1MichiganMWRASExtrapolatedCriticalHighTemperatureGradeReplicate MeasuredCriticalHighTemperature,°C

Extraction1 Extraction2 Extraction31 142.7 128.9 130.12 136.0 130.2 130.33 130.3 134.3 131.3Average 136.3 131.1 131.1StandardDeviation 6.2 2.8 2.2COV,% 4.55 2.15 1.50AverageofNineTests 132.9StandardDeviationofNineTests 4.4COVofNineTests,% 3.29TableB2MichiganPCRASExtrapolatedCriticalHighTemperatureGradeReplicate MeasuredCriticalHighTemperature,°C

Extraction1 Extraction2 Extraction31 150.3 162.4 136.62 127.7 241.4 160.83 174.8 172.1 184.3Average 150.9 192.0 160.5StandardDeviation 23.5 43.1 23.8COV,% 15.6 22.4 14.9AverageofNineTests 167.8StandardDeviationofNineTests 33.0COVofNineTests,% 19.68TableB3OregonBlendedRASExtrapolatedCriticalHighTemperatureGradeReplicate MeasuredCriticalHighTemperature,°C

Extraction1 Extraction2 Extraction31 152.8 140.0 147.12 140.2 138.8 147.93 143.6 139.0 149.2Average 145.5 139.3 148.1StandardDeviation 6.5 0.6 1.1COV,% 4.5 0.5 0.7AverageofNineTests 144.3StandardDeviationofNineTests 5.1COVofNineTests,% 3.56

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TableB4NewHampshirePCRASExtrapolatedCriticalHighTemperatureGradeReplicate MeasuredCriticalHighTemperature,°C

Extraction1 Extraction2 Extraction31 126.6 147.0 144.52 170.6 144.1 145.43 126.7 147.1 151.8Average 141.3 146.1 147.2StandardDeviation 25.4 1.7 4.0COV,% 17.9 1.2 2.7AverageofNineTests 144.9StandardDeviationofNineTests 13.1COVofNineTests,% 9.08TableB5GeorgiaPCRASExtrapolatedCriticalHighTemperatureGradeReplicate MeasuredCriticalHighTemperature,°C

Extraction1 Extraction2 Extraction31 138.3 136.9 150.52 136.6 136.0 189.43 136.8 139.5 255.6Average 137.2 137.5 198.5StandardDeviation 0.9 1.8 53.1COV,% 0.6 1.3 26.8AverageofNineTests 157.7StandardDeviationofNineTests 40.5COVofNineTests,% 25.68TableB6TexasMWRASExtrapolatedCriticalHighTemperatureGradeReplicate MeasuredCriticalHighTemperature,°C

Extraction1 Extraction2 Extraction31 138.3 136.9 150.52 136.6 136.0 189.43 136.8 139.5 255.6Average 137.2 137.5 198.5StandardDeviation 0.9 1.8 53.1COV,% 0.6 1.3 26.8AverageofNineTests 157.7StandardDeviationofNineTests 40.5COVofNineTests,% 25.68


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