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<PPBind),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