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Performance-RelatedSpecifications:IntegrationoftheAsphaltMixture
PerformanceTester(AMPT)DavidJ.Mensching,Ph.D.
OfficeofPreconstruction,Construction,andPavementsNESMEAAnnualConference
Hartford,CTOctober18,2017
• OfficeofPreconstruction,Construction,andPavements
• OfficeofInfrastructureResearchandDevelopment
• OfficeofTechnicalServices
Acknowledgements
• Owneragenciesshortonfunding– Needmorepavementlife– Lessrehab– More“bangforbuck”
• MAP-21introducedperformance-basedadministeringoffederalfunds– FHWAestablishedmeasuresforStatestosetowntargets
Background
• Late 1980s-Early 1990s: Strategic HighwayResearch Program– Superpave mixture design approach– Performance grade binders– But no viable performance tests for mixture
• National Cooperative Highway Research Program– 9-19: Identify simple performance tests for Superpave
(rutting, fatigue)• Dynamic modulus, flow number, flow time
– 9-29: Produce prototype, conduct ruggedness andinterlaboratory studies
• Simple Performance Tester (now known as AMPT)was born!
AMPT– AddressingaNeed
• Temperaturerangefromabout4° to70°C• Computer-controlleddevice
• Softwarebuilt-inforvarioustestprocedures
• Fundamentaltests– Stressandstrainmodeling– “Bulktesting”– PavementMEorFlexPAVETM
• Kitsavailableforothertests
AMPT
Planning&PavementDesign
Specify MixDesign Construct&Accept
Preserve&Rehab
ContinuumofPerformance
PRS
• Asphaltdistress?• Frequencyofsampling/testing?• Howtoquantify/managedata?• Costoflifeloss?• Appropriatemethodstomeasure?
Performance
• Preserveassetsandminimizewholelifecosts
• Operateinafinanciallysustainablemanner
• Providesaframeworktoimproveperformanceonalong-termbasis
• Aplanisnowrequired!
OverviewofAssetManagement
• HowcanIextendpavementlife?– Specificationdevelopment/targets– Exceedingperformancethresholds– Optimizingassetmanagementplan
• HowcanImeasureperformanceupfront?– EffectofRAP,WMA,etc.,andpavementstructure
– Laboratorytestingandconditioning• Fundamental• Index-based• Lotsoftests
TwoQuestions
NeedforUniformity
ContinuumofSpecificationsR
isk
100
QAMethodType of Specification
0End-Result Warranty
Contractor
Owner
Performance
Performance-RelatedSpecifications(PRS)
“QAspecificationsthatdescribethedesiredlevelsofkeymaterialsandconstructionqualitycharacteristics thathavebeenfoundtocorrelatewithfundamentalengineeringpropertiesthatpredictperformance”
TransportationResearchCircularNumberE-C137GlossaryofHighwayQualityAssuranceTerms
IdentifyAQCsandTargetValues
EstablishPerformanceCriteria
ModelPerformance
DesignAQCvs.As-ConstructedAQC
CompareAs-BuiltandAs-Designed
PayFactorTime
Design
Constructed
SOFTWARE
Value of Performance?
HowPRSWorksPlanning
PavementDesign
• Longtermpavementperformancepredictedfromfundamentalengineeringproperties
• Incentivesanddisincentives justifiedthroughreductionorincreaseinpavementlife
• Allowcontractorstobemoreinnovativeandmorecompetitive
BenefitsofPRS
• Testingefficiencyandsimplicity– Completed/Continuous
• Standardizationoftestmethods– Ongoing
• Reliabilityofperformancepredictionmodels– Complete
• Performancevolumetricrelationships– Ongoing
• SameprinciplesandmethodsbetweenmixdesignandPRS– Ongoing
ChallengeswithPRS
StandardizationofTestMethods
SpecimenPrepAASHTOR83
FULLSIZESPECIMEN SMALLSIZESPECIMEN
SpecimenPrepAASHTOPPXXX
DynamicModulusAASHTOT378
DynamicModulusAASHTOTPXXX
CyclicFatigueAASHTOTP107
CyclicFatigueAASHTOTPXXX
StressSweepRuttingAASHTOTPXXX
ReliabilityofPerformancePredictionModels
59asphalt mixtures,includingWMAand
RAPmixtures,from55pavementsections
FHWA-ALFSections
0
10
20
30
40
50
60
70
1.E+00 1.E+02 1.E+04 1.E+06
Dam
age
Area
(%)
No. of Cycles
ControlCRTRSBS
(a) FlexPAVE Prediction
0
20
40
60
80
100
1.E+02 1.E+03 1.E+04 1.E+05
Cra
ck A
rea
(%)
No. of Cycles
ControlCR-TBTerpolymerSBS-LG
Field Measurement(b)
0
5
10
15
0 3 6 9 12 15
Pre
dict
ed R
D fr
om S
-TS
S (m
m)
Measured RD (mm)
FHWA NCAT MIT-WMA MIT-RAP LOE
0
5
10
15
0 3 6 9 12 15
Pre
dict
ed R
D fr
om S
-TS
S (m
m)
Measured RD (mm)
NCAT MIT-WMA MIT-RAP LOE
BeforeCalibration
AfterCalibration
19
RutDepthPredictions
• Predictas-builtperformance– Withoutperformancetesting
• DatabasedevelopedatTFHRC• Expansionunderwayinshadowprojects
– Willuseplant-producedvariations• Agencyandcontractorguidanceforplanningpurposes
PerformanceVolumetricRelationships(PVR)
• Useoffundamentalteststocapturevariancebetweenas-designedandas-builtAQCs
• AsphaltMixturePerformanceTester(AMPT)usedinperformance-engineeredmixturedesign(PEMD)
• Performancevolumetricrelationshipsusedinconstruction
• Structuralresponsemodel(stressesandstrains)
FHWAPRSInitiative
• Useoffundamentalteststocapturevariancebetweenas-designedandas-builtAQCs
• AsphaltMixturePerformanceTester(AMPT)usedinperformance-engineeredmixturedesign(PEMD)
• Performancevolumetricrelationshipsusedinconstruction
• Structuralresponsemodel(stressesandstrains)
FHWAPRSInitiative
• Fundamental– Howmuchdistress?Howmuchlife?– Stressesandstrains– Materialproperties(i.e.,modulus)– Usewithstructuralresponsemodel– Manytemperature/loadingconditionsrepresented
• Index-Based– Go/no-go:correlation-based– Someengineeringproperties,someempirical
• Moretiedtoamaterialdatabase– Notusedwithstructuralresponsemodel(FlexPAVE)– Onlyafewtemperature/loadingconditionsrepresented
Performance-engineeredmixturedesign(balancedmixturedesign)
• Fundamental– Howmuchdistress?Howmuchlifegained/lost?– Stressesandstrains– Materialproperties(i.e.,modulus)– Usewithstructuralresponsemodel– Manyloadingconditionsrepresented
• Index-Based– Go/no-go:correlation-based– Someengineeringproperties,someempirical
• Moretiedtoamaterialdatabase– Notusedwithstructuralresponsemodel– Afewloadingconditionsrepresented
• Cost-efficientwaytoaccountforrelevantdistress!
Performance-engineeredmixturedesign(balancedmixturedesign)
FHWAPRS
• GraphicaluserinterfacessimilartoSameclimate,trafficinputs– Fewerunboundlayerinputsneeded
• AASHTOTP107resultsproventobecompatiblewithK1,K2,K3fatiguecoefficients
• AASHTOT378(|E*|)remainscriticalinput
AASHTOWare PavementME-FlexPAVETMCompatibility
• FlexMATTM – Excelspreadsheet– Analyzescyclicfatigue,|E*|,andSSRdata– Importfilesdirectly– Outputà FlexPAVETM
• FlexPAVETM – performancepredictiontool– PEMDthroughacceptance– Simulateas-designandas-builtperformance
FlexMATTM andFlexPAVETM Available
FlexMATTM
FlexPAVETM
PredictsPerformance!
PredictsPerformance!
Performancecriteriadeterminespavementlife!Compareas-designlifetotheas-builtpavement
lifeinPASSFlexTM toassignpayfactors!
• Time-temperaturesuperposition– Majorbenefit– Reducestestingtime/specimens– Enablesrobustnessofmodels
• Fundamentalpropertiesrequiredtodescribebehavioracrosswide-rangeofconditions
• Allowsfordirectincorporationofpavementstructureintopredictions
MaterialBehaviorAcrossAllLoadingConditions
• Time-temperaturesuperposition– Majorbenefit– Reducestestingtime– Enablesrobustnessofmodels
• Fundamentalpropertiesrequiredtodescribebehavioracrosswide-rangeofconditions
• Allowsfordirectincorporationofpavementstructureintopredictions
MaterialBehaviorAcrossAllLoadingConditions
FHWAShadowPRSProgram
• Howwouldprojecthavebeenaccepted,(andcontractorpaid),ifPRSwereused
• UnderstandwaysthatPRSmayimpactnormaltestingandacceptanceoperations
ObjectivesofShadowPRS
• DOTdeterminesproject(s)• DevelopsamplingplanwithFHWA,NCSt.,ARA– 10plant-producedsamples– Proficiencysample(1projectonly)– Mixdesignreplicationsample
• TrainingbeforeAMPTtestingbegins• Volumetrictestingasnormallydone• AMPTtestingwheneverDOThastime
HowWillThisAllWork?
ShadowPRSStatus
• MarylandSHA– Underway(10projects)• MaineDOT– Underway• MissouriDOT– Underway(3projects)• OntarioMOT– Underway• WesternFederalLands– 1st ProjectComplete
• Marketingofsuccessstories
• National/International– TRBAnnualMeeting–Discussionofissues,bestpractices,futureefforts
– 164members• 28DOTsrepresented
• Regional–User-ProducerGroups– StateAsphaltPavingAssoc.meetings
AMPTUsersGroup
AsphaltTechnologyGuidanceProgram(ATGP)
Long-Life Asphalt Pavement for the 21st Century
Office of Asset Management, Pavements, & Construction
ProgramFocusAreas
• ProvideSupporttoNationalInitiatives– IncreasedPavementDensity
– IncreasedRAP/RASUsage
– UnderstandingGTRTesting
– MixturePerformanceTestingandtheAMPT
– StoneMatrixAsphalt
– BinderPerformanceTesting
– Long-TermAging39
ProgramFocusAreas(2)
• EquipmentDevelopment&Refinement
– AsphaltMixturePerformanceTester(AMPT)• StandardizationofEquipment,TestMethods
– BinderPerformanceTesting
• DevelopmentofNewQAConceptsforHMA– Performance-Based/RelatedandRisk-BasedAcceptance
• AdvancedRapidTestTools– AIMS,CoreLok,CoreDry,Small-ScaleGeometry
40
41
SolutionstoAgencyNeeds
• Project-SpecificWorkplans–MaterialCharacterization
• HighRAP/RAS,GTR,SMA,PRS…
–MixDesignReplicationandTesting–MixProductionTesting–PerformancePrediction–TrainingandDemonstration
• Questions?• Contactinformation(PRSandShadow)
– RichardDuval– 202.493.3365– [email protected]
• Contactinformation(AMPTandPRS)– DavidMensching– 202.366.1286– [email protected]
Thankyou!
• Pavementinventoryandconditions(NHS)• Objectivesandmeasures• Performancegapidentification• Lifecycleplanningandriskmanagementanalysis
• Financialplan• Investmentstrategies• Shorttermperformancemeasureskeytoinvestfundseffectivelyandmeetlong-termgoals!
• Performancepredictionleadstosmartplanning!
AssetManagementPlans
• Lowtemperaturesorfastloadingrate– Thermalcracking
• Intermediatetemperaturesandloadingrates– Fatiguecracking– Durabilitycracking– Thermalfatigue
• Hightemperaturesandslowloadingrates– Rutting– Increasedoxidativeaging
• Insufficientstructure– Rutting– Fatiguecracking
• Allinfluenceridequality
AsphaltPavementPerformance
PRSFramework
SamplingofMixtures/DatafromPavingProject
PerformanceTestsinAMPT
FlexMATTMExcel-BasedData Analysis
FlexPAVETMPavement
PerformanceAnalysis
PredictionofLife
ApplicationofPay
FactorsinPASSFlex™
Incentives/Disincentives
PerformanceMonitoring&Feedback
TestingEfficiencyandSimplicity
Small Specimen
|E*| Tests Fatigue Tests
Large Specimen
|E*| Tests
Fatigue Tests
TestingEfficiencyandSimplicity(2)
LargeSpecimen SmallSpecimen
SteelPutty Devcon 10110 Devcon 10240
Working Time 10 – 20min. 5min.
FunctionalCure 16hours 1hour
AmountofPutty(perspecimen) 100g 3g
• Addfailurecriterion• Simplificationoflanguage• AMPT-specific• Removalofspreadsheetderivation• Newstrainselectionguidance• Small-specimenappendix• Instructionalvideos(linksavailable)
AASHTOTP107Revisions
• Testingisconductedatmixdesignphase
• Runpredictionstoestablishas-designpavementlife
• Sameprinciplespresent– Predictionusingcyclicfatigueandshiftmodels
– Payfactorsassignedonalifedifference
SamePrinciplesandMethodsinDesignandPRS
• TransportationPooledFundStudy(TPF(5)-178)– Purchase,installationof29AMPTs– NHICourse(over80trainees)– Interlaboratory studyoneffectofairvoids– Nationalworkshop– Equipmentspecification,andothers!
• Teststandarddevelopment,improvement,andrevision
• Instructionalvideos,TechBriefs• PRSshadowimplementation(TFHRC-led)• PRSworkshops(2017,2018,2019)• MATTprojects/training• UserGroupsatTRBandregionalmeetings
AMPTImplementation
AMPTOverview
DynamicModulusTest
• MixtureStiffness• Rutting• FatigueCracking
StressStrain
s e00
lT
Tp
Timese
E*0
0=
Dynamic Modulus Phase Angle
TTf
p
l= (360)
DynamicModulusMasterCurve
Reduced Frequency, Hz
10,000,000
1,000,000
100,000
10,000
1,000
115°F
70°F
40°F
FIT
1.0E-06 1.0E-04 1.0E-02 1.0E+00 1.0E+02 1.0E+04 1.0E+06
E*min=4,259 psi
E*max=3,376,744 psi
R2= 0.9978Se/Sy= 0.038 3
2
1
0
-1
-2
-3Lo
g Sh
ift F
acto
r0 50 100 150
Temperature
E*,
psi
High Temperature: 0.4s pulse, 3.6s rest
20°C: 0.4s pulse, 1.6s rest
0.4s x 200 cycles for each loading block
0.4s x 200 cycles for each loading block
StressSweepRutting(SSR)Test
0.0%
0.5%
1.0%
1.5%
2.0%
0 200 400 600
Perm
anen
t Str
ain
Number of Cycles
S-TSS: TH
100 psi70 psi
130 psi
SSR:TH
0.0%
0.5%
1.0%
1.5%
2.0%
0 200 400 600
Perm
anen
t Str
ain
Number of Cycles
S-TSS: TL
TL 70 psi 100 psi 130 psi
SSR:20°C
• DraftprocedurereadyforconsiderationbyAASHTO
• FlexMATTM-Ruttingavailable– Singletabspreadsheet
• Confinedtesting(10psi)• 1daytocompleteallreplicates• Modelpredictspermanentdeformationatallloadingconditions!
SSRTest
• Fundamental,repeatedloadingtest• Directtension(pull-pull)• Small-specimentestingavailable(AASHTOTPxxx)
• AASHTOTP107– revisionsoutforballot!
• Materialbehavioracrossallpossibleloadingconditions!
AMPTCyclicFatigue
• Pavementpredictionsoftwarebuiltfrommodels
• Fieldvalidation– 59mixtures– 55differentpavementstructures
• Developlaboratory-to-fieldtransferfunctions
• Volumetrics haveaseatatthetable!
FieldValidationofAMPTCyclicFatigue
• AASHTOT378|E*|– Complete!• AASHTOTP107– Ruggednessandprecisionandbiasunderway
• Small-specimencyclicfatigue–Ruggednessandprecisionandbiasunderway
• Small-specimen|E*|– comingsoon
Ruggedness,Precision,andBias
InitialPVRDatabase
Relative notabsolutedistress
ApplicableforaparticularstructureandtrafficBUTwecangenerateacatalogwithFlexPAVETM
AnchorpointisstandardSuperpave• MinimumVMAforNMAS• 4%DesignAirVoids• 7%AirVoidsIn-PlaceDensity
• Cylindricalspecimens– AASHTOR83forfull-size– Draftprocedurereadyforsmall-size
• Equipmentrequired– Superpave gyratorycompactorandmolds– Coredrill(bitsdependonspecimensize)– Wetsaw– Waterbathorotherdevice(forGmb)– Engineeringsquare,pianowire
StandardSamplePreparation
PRSSoftware
AMPT+PerformancePrediction
PredictedRuttingPredictedCracking
ü Structure üClimateüTraffic
AMPTCyclicFatigueProcess
Preparation- Cylindricalspecimen- 100mmx130mm- Small-specimen:38mmx110mm
- Endplategluing,clampsystembeingexplored- 2-3daysformix
Testing- Dynamicmodulus
fingerprintforspecimenvariability
- Pull-pullfatiguetest- Strainlevelbasedon
TFHRCdatabase- Testtemperaturebasedonlocationofinterest- Loaduntilcrackforms
- 1-2daysformix
Analysis- AMPTautomatically
capturesdataforanalysis- CalculatedamageviaFlexMAT orFlexPAVE
- AssignmixturerankingsoruseFlexPAVE
- 1-2hoursformix
Aboutoneweekpermixture…worthitwhenconsideringthecostofprematurefailure?
• Standardsamplepreparation• AASHTOWare PavementMEcompatible• Ruggedness,precisionandbiasunderway
• FlexMATTM &FlexPAVETM available• Predictsperformance!• Materialbehavioracrossallpossibleloading/temperatureconditions!
AdvantagesofAMPTCyclicFatigue
FlexPAVETM SimulationsFHWA-ALFSections
This image cannot currently be displayed.
• Accept‘shadow’mixturesbasedontheperformanceengineeredmixdesign(PEMD)approach
• Collectvolumetric-basedacceptancequalitycharacteristics(AQCs)duringconstruction(PASSFlexTM)– Thesewouldbeusedtodeterminehypotheticalcontractorpay
TwoMajorTasksforDOT
• ProficiencyTesting– EnsurerepeatableresultswithseparatelaboratoryAMPT
– Onlydoneonfirstshadowproject• PEMDTesting
– Baselinefortheas-designedcondition– Neededindesignphaseofeachproject
• ProductionTestingwithAMPT(Shadowonly)– EstablishPVR
• ProductionTestingwithVolumetrics
MaterialTesting
• UnderstandingconceptofPRS– Understandingpavementfatigueandruttingusing
fundamentaltestprocedures– PavementperformanceasfunctionofAQCs– ConstructionAcceptance
• AMPTtraining– ARA,NCSU,&FHWAwillworkwithStateAgencyto
determinethebestsolutionfortraining.TheFHWA-MATTprovidesopportunitiesforDOTstolookovertheshoulderofitspersonnelwhentestingforperformance.
• PRSSoftwaretrainingandanalysissupport• PotentialforFHWAprojectfundingsupport• PotentialforMobileAsphaltTestingTrailersupport
WhatWillaDOTGetOutofShadowProjectParticipation?
69
ProgramObjectives
• AdvancePerformance
• AdvanceQualityAssurance
• AdvanceInnovation
CourtesyofAntonPaar
