AsphaltExpertTaskGroupUpdateandEmergingTopics

MatthewCorrigan,P.E.U.S.DOT|FederalHighwayAdministration

Preconstruction,Construction,andPavementsOctober2017

• ForumforGovernment,Industry,andAcademia

• Discussionofongoingasphaltbinderandmixturetechnology

• Providetechnicalinputforcurrentandfutureresearch,development,andspecifications.

AsphaltExpertTaskGroups

• AsphaltMixture&ConstructionETG• LastmeetinginBozemanonSept20-21,2017

• POC– MatthewCorrigan

• AsphaltBinderETG• LastmeetinginBozemanonSept19-20,2017

• POC– MatthewCorrigan

• SustainablePavementsTWG• POC– GinaAhlstrom

AsphaltExpertTaskGroups

OpenMeetingsAllareWelcome!

www.AsphaltETGs.org

UpcomingETGMeetingsToBeAnnounced(Nexttentative- weekofApril23,2018)

PastETGMeetingsSeptember2017— Bozeman,MTMay2017— Ames,IASeptember2016— FallRiver,MAApril2016— SaltLakeCity,UTSeptember2015— OklahomaCity,OKApril2015—FallRiver,MASeptember2014—BatonRouge,LA

• AsphaltMixturePerformanceTester(AMPT)• PerformanceTestsforCracking/Fatigue• RAP&RASAsphaltBinderReplacement

• PerformanceRelated/BasedSpecifications• ΔTc andrelatedrheologicalparameters• ProvidetechnicalinputtoAASHTOCommitteeon

Materials&Pavements(COMP)&assistimprovement,revision,andupdateofstandardsandspecifications

CurrentAsphaltETG- Activities

• BalancedMixDesign• MSCRBinderGrading• GroundTireRubber

• ResultsusedforMEDesignandPRS/PBSinputs

• AdoptedAASHTOStandards(2017):– R83-17forpreparationofAMPTtestspecimens

– T378-17forDynamicModulus|E*|andFlowNumber(Fn)

– R84-17fordeveloping|E*|mastercurves

– TP107-14(2016)forCyclicFatigue(cracking)

– anddraftTPXXforStressSweepRutting

AsphaltMixPerformanceTester(AMPT)www.fhwa.dot.gov/pavement/asphalt/tester.cfm

AlreadyinvestedinAMPTequipmentforPavementME …theAMPTcandomuchmorethanjust|E*|testing!!

1. Heritageand“pedigree”ofthetheory–aerospaceindustryapplicationforsolidrocketpropellant

2. Needforaperformancetestthatwouldbedefensible,not empiricalcorrelations

3. AASHTOTP107-14(2016)DeterminingtheDamageCharacteristicCurveofAsphaltMixturefromDirectTensionCyclicFatigueTests

4. Connectmixdesign,construction,andacceptancebymeansofdistressandperformanceprediction- notjustapass/failtest

WhyAMPTCyclicFatigueTest?

*RefertoETGPresentationatpreviousNEAUPGforsignificantlymoredetails

*

5. Thetesttellsyoualotaboutyourmix!!!– Responseundermultiplestrains:

STRUCTURE/TRAFFIC– Responseundermultipleloadrates:TRAFFIC– Responseundermultipletemperatures:SEASONAL– Moreinformationgainedfromthistestprotocoland

analysisthanfromothersingletestsatasinglerate/temperature

6. Connectmixdesign,construction,andacceptancebymeansofdistressandperformanceprediction- notjustapass/failtest

WhyAMPTCyclicFatigueTest?

RAP/RASTaskForcewithinETG:• AASHTOPP78-17DesignConsiderationsforRAS• ImprovementstoM323Superpave Design

– Table2vsTable3requirementsandlimits– Definitions(PbRAP),references(MSCR&LTPPBind),appendices,editorial,andorganization

– RAPbinderratio(RAPBR)emphasiswithbindergradeadjustmentguidelines

– EvaluateblendedbinderpropertiestoalignwithPP78recommendations

– FuturegoaltoincorporatebothcombinedRAP&RASmaterialstogetheringuidance

ReclaimedAsphaltPavement(RAP)ReclaimedAsphaltShingles(RAS)

ETGRAP/RASTaskForce

Focusonthebrittlenessoftheblended binder:• EstimatebrittlenessoftheblendedbinderwiththeBendingBeamRheometer(BBR)

ΔTc =Stiffnesscriticaltemp(S)– theRelaxationcriticaltemp(m-value)

• PreviousworkbyM.Anderson,T.Bennert,G.ReinkeindicatesthatwhenΔTc < -5°Cthereisasignificantlossofcrackingresistance.

BalancedMixDesignTaskForce

• Threemainapproacheswereidentifiedforpotentialuse:

Fordetails,refertothe18Oct2017NEAUPG.pptprovidedbyShaneBuchanan

BalancedMixDesignTaskForce

CurrentActivities• InformationOutreach

• PresentBMDconcepts• HighlightthebenefitofBMDconcepts

• FieldAcceptance• DefinevariousapproachesforacceptanceprotocolswithinaBMDapproach

PerformanceRelatedSpecifications

“QAspecificationsthatdescribethedesiredlevelsofkeymaterialsandconstructionqualitycharacteristics thathavebeenfoundtocorrelatewithfundamentalengineeringpropertiesthatpredictperformance”

TransportationResearchCircularNumberE-C137GlossaryofHighwayQualityAssuranceTerms

IdentifyAQCsandTargetValues

EstablishPerformanceCriteria

ModelPerformance

DesignAQCvs.As-ConstructedAQC

CompareAs-BuiltandAs-Designed

PayFactorTime

Design

Constructed

SOFTWARE

Value of Performance?

HowPRSWorksPlanning

PavementDesign

BenefitsofPRS

• Longtermpavementperformancepredictedfromfundamentalengineeringproperties

• Incentivesanddisincentives justifiedthroughreductionorincreaseinpavementlife

• Allowcontractorsflexibilitytobeinnovative andcompetitive

PRSInitiative

• Useoffundamentalteststocapturevariancebetweenas-designedandas-builtAQCs

• AsphaltMixturePerformanceTester(AMPT)usedinmixturedesign

• Performancevolumetricrelationshipsusedinconstruction

• Structuralresponsemodel(stressesandstrains)

PRSInitiative

• Fundamental– Howmuchdistress?Howmuchlife?– Stressesandstrains– Materialproperties(i.e.,modulus)– Usewithstructuralresponsemodel– Manytemperature/loadingconditionsrepresented

• Index-Based– Go/no-go:correlation-based– Someengineeringproperties,someempirical

• Moretiedtoamaterialdatabase– Notusedwithastructuralresponsemodel(FlexPAVE)– Onlyafewtemperature/loadingconditionsrepresented

FHWAPRS

Cost-efficientwaytoaccountforrelevantdistress!!

FlexMATTM andFlexPAVETM Available

• FlexMATTM – Excelspreadsheet– Analyzescyclicfatigue,|E*|,andSSRdata– Importfilesdirectly– Outputà FlexPAVETM

• FlexPAVETM – performancepredictiontool– PEMDthroughacceptance– Simulateas-designandas-builtperformance

FlexMATTM andFlexPAVETM Available

• FlexMATTM – Excelspreadsheet– Analyzescyclicfatigue,|E*|,andSSRdata– Importfilesdirectly– Outputà FlexPAVETM

• FlexPAVETM – performancepredictiontool– PEMDthroughacceptance– Simulateas-designandas-builtperformance

PredictsPerformance!!

MaterialBehaviorAcrossAllLoadingConditions

• Time-temperaturesuperposition– Majorbenefit– Reducestestingtime– Enablesrobustnessofmodels

• Fundamentalpropertiesrequiredtodescribebehavioracrosswide-rangeofconditions

• Allowsfordirectincorporationofpavementstructureintopredictions

MaterialBehaviorAcrossAllLoadingConditions

• Time-temperaturesuperposition– Majorbenefit– Reducestestingtime– Enablesrobustnessofmodels

• Fundamentalpropertiesrequiredtodescribebehavioracrosswide-rangeofconditions

• Allowsfordirectincorporationofpavementstructureintopredictions

FHWAisworkingwiththeAsphaltInstitutetoassistStatestoeffectivelyunderstandandimplementMSCR.• TechnicalBriefFHWA-HIF-11-038

– www.fhwa.dot.gov/pavement/asphalt/index.cfm

• ResourcespostedonAI’swebsite– www.asphaltinstitute.org/public/engineering/mscr-information.dot

MultipleStressCreepRecovery(MSCR)

• AASHTOT350-14andM332-14• EmphasisondeterminingJnrdiff

– Jnr changewithstressincrease– ImpactofstressselectiononJnr whilestayingwithinthebinder’slinearrange

– Jnr slopedetermination– EgradeJnrdiff waiver

MSCR Jnrdiff TaskForce

• ExtensivedevelopmentworkconductedonrubbermodifiedbinderwithCCgeometry– Revealsthepracticalandrheologicalchallenges– SuitablemeasuringgeometryforPGmeasurementsofgroundtirerubbermodifiedasphaltbinders

– Finalizedtooldimensionsandrequirements• DSR…concentriccylindergeometryalsocalled“Cup&Bob”geometry– “requiredtoenablegoodrheology!”…“Gapsizematters!”

DSRConcentricCylinder(CC)TaskForce

Smallcylinderinsideabigcylinderenablestheuseoflargegaps

AbsoluteRelative CC17SPGap≈6.2mmSuitableforneatandRTFOasphaltbinder(highPGtemperatures)

CC10SPGap≈9.5mmSuitableforPAVasphaltbinder(intermediatePGtemperatures)

CourtesyofA

nton

Paar

DraftAASHTOteststandarddevelopment• TPXX-YYDeterminingtheRheologicalPropertiesofAsphaltBinderContainingGroundTireRubberParticulatesUsingConcentricCylinderGeometryintheDynamicShearRheometer(DSR)– PGHightemperaturecharacterization– Proceduretocalibrate/verifytorqueandtemperature

• Future– RTFOagingandBBRtesting

DSRConcentricCylinder(CC)TaskForce

TaskForcewithinETG• Draftwhitepaperfinalized(tobepublished)• Whichrheologicalparameter

– criticaltemperaturechange(ΔTc)– Glover-Rowe(GR)– rheologicalindex(Rvalue)– crossoverfrequency(ωc)

• Alloftheseparameterscanbeinterrelatedfromunderstandingtherelationshipbetweenloadingtime(orfrequency)andtemperature.

Re-refinedEngineOilBottoms(REOB)VacuumTowerAsphaltExtender(VTAE)

Focusonthebrittlenessoftheblended binder:• EstimatebrittlenessoftheblendedbinderwiththeBendingBeamRheometer(BBR)

ΔTc =Stiffnesscriticaltemp(S)– theRelaxationcriticaltemp(m-value)

• PreviousworkbyM.Anderson,T.Bennert,G.ReinkeindicatesthatwhenΔTc < -5°Cthereisasignificantlossofcrackingresistance.

ΔTc andrelatedrheologicalparameters

• Current20hourPAVdoesnotrepresentenoughagingtoidentifycriticalconditionsortomatchfieldagingbypavements

• 40hourPAVcorrelatedwithperformance• Optionsforachievingadditionalagingarebeingexplored– Thinnerasphaltfilms

• PAVorUSAT(UniversalSimpleAgingTest)

– PredictedΔTc fromdifferencebetween:• Rateofchange:originalbindertoRTFOTto20hourPAV

ΔTc andrelatedrheologicalparameters

• Otherparametersthatprovidesimilarinfo?– AgingdecreasesΔTc,increasesR-value,decreasescrossoverfrequency,andincreasescrossovertemperature

• RelationshipbetweenΔTc andTwc– Crossovertemperature(Twc)– measuredat10radians/secwherethephaseangleis45°ortand =1

– Twc iseasytomeasureonRTFOagedbinder

ΔTc andrelatedrheologicalparameters

• Laboratoriesroutinelyconfusebarometricpressurewiththebarometricpressurereportedbythelocalweatherstation– Barometricpressurereportedbylocalweatherstationiscorrected tosealevel

• Uselessforourpurposes!

– Absolutevacuumgageshouldbespecified– Tievacuumleveltoelevation

PAVDegassing

Whenusingavacuumgagetocontrolthedegassingpressure,thegaugereadingsgivenbyEq.4calculatedusingthelaboratoryelevationtothenearest100feetshallbeusedtocontrolandreportthevacuumduringthedegassingcycle.Equation4accountsforchangesinatmosphericpressurewithelevation.Noadditionalcorrectionsforlaboratorybarometricpressure,temperature,humidity,etc.shallbeappliedtothevacuumgagereadingregardlessofinstructionssuppliedbyanyvendors,instrumentsoftware,orothersource.Thevacuumgagereadingshallbereportedandcontrolledtothenearest0.5inHg(0.2kPa).

PAVDegassing- Proposal

• TheabsolutepressurecalculatedinaccordancewithEq.4shallbe5.0±0.50inchesofmercury(17± 1.7kPa).

• Asaminimumthegageshallbereadandreportedtothenearest0.5inchesHg(2kPa)

PAVDegassing- Proposal

1.Howcanwemeasurepanflatness?a. Currenttechniquesarenotsatisfactory

2.Howdoweobtaindirectmeasureofflatness?a. Profileisneeded

3.Howdotypicalpanflatnesserrorsaffecttestresults?a. Ifflatnessandpropertyvs.thicknessdata

areavailable,itcanbeestimatedb. Determinedexperimentallybyusing

warpedpans

PAVPanWarping

4. Howcanwemeasurepanflatnessinspecificationscenario?

5. Whatarerealisticlimitsforspecifyingpanflatness?

PPAVPanWarping

MeasuringjigandphotoprovidedbyDr.DavidAnderson

• Pandividedinto28segments• Profilemeasuredatcentroidofeachprofile

• Propertiesforeachsegmentcanbeweightedaslongaseffectofthicknessonpropertiesisknown

• Canalsoestimateeffectofpanandvessellevelness

ProfilingandCalculatedEffect

ProfilingandCalculatedEffect

CourtesyofDr.DavidAnderson

• A1%increaseinfielddensity(1%lessairvoids)canincreaseasphaltpavementservice-life10+%!(conservatively)

• Today’scompactiontargetistypically92%ofmaximum(Gmm )(8%airvoids),withvaryingrequirementsfortheareanearthelongitudinaljoint

EnhancedDurabilitythroughIncreasedIn-PlacePavementDensity

IncreasedDensityPavementstargeta1-2%increaseacrosstheentirepavement!

– Just1%more…makesahugedifference!

CA

AZ

CO

NM

TX

OK AR

LA

MO KY

AL GA

FL

VA

OH

MI

AK

MT

NV

MEWA

OR

UT

KS

ID

WY

ND

SD

MN

NE

WI

IA

IL IN

MS

TNSC

NC

WV

PA

NY

CTNJDEMD

DCHI

Key:

PR

Demonstration projects (10)

EnhancedDurabilityofAsphaltPavementsthroughIncreasedIn-Place

PavementDensity

Workshop Only (18)

Mobile AsphaltTesting Trailer (2)

EasternFederalLands

• Fieldexperiment– Phase1– 10statesselected– Projectscompletedin2016

• Extendfieldexperiment– Phase2– 9statesselected– Projectsunderconstructionin2017andearly2018

• Potentialadditionalfieldprojectsin2018?• FHWA’sbestpracticescommunication

– Summarydocument– TechBrief– Additionalworkshops(fundingdependent)

NextSteps

CA

AZ

CO

NM

TX

OK AR

LA

MO KY

AL GA

FL

VA

OH

MI

AK

MT

NV

MEWA

OR

UT

KS

ID

WY

ND

SD

MN

NE

WI

IA

IL IN

MS

TNSC

NC

WV

PA

NY

CTNJDEMD

DCHI

Key:

PR

Demonstration projects (10)

EnhancedDurabilityofAsphaltPavementsthroughIncreasedIn-Place

PavementDensity

Workshop Only (18)

Mobile AsphaltTesting Trailer (2)

EasternFederalLands

Ph. 2 Demonstration (9)

SummaryDocument

http://eng.auburn.edu/research/centers/ncat/files/technical-reports/rep17-05.pdf

NCATReport17-05

“DemonstrationProjectforEnhancedDurabilityofAsphaltPavementsthroughIncreasedIn-placePavementDensity”- July2017

Testsectionshadincreased%TMD:• 8of10statesachieved>1.0%increase• 7of10statesachieved>94.0%Gmm

• 6of10statesachieved>95.0%Gmm

Willtherebechanges?• 7of10statesarechangingspecifications

Canweachieveincreaseddensity?

• MobileAsphaltPavementMaterialsLab– SiteVisits– FieldData/Testing/Evaluation– Use/DemoEmergingTestDevices– POC:MatthewCorriganand

DavidMensching

FHWAFieldSupportMobileAsphaltTestingTrailer(MATT)

You!!Thank Discussion/Comments/Questions

FHWA’sMobileAsphaltTestingTrailerOfficeofAssetManagement,Pavement,andConstruction

www.fhwa.dot.gov/pavement/asphalt