neaupg ncat friction studies - heitzman...w3 mix sn64 = -44.0 + 1.97 dft 60 2.00 0.293 50.0 0.707 12...
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PavementFrictionDr.MichaelHeitzman,PE
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Topics TWPD(NCATThreeWheelPolishingDevice) DFT(DynamicFrictionTester) DOTMixLabStudy HighFrictionSurfaceTreatment(HFST) NCATTestTrackResults
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TWPDDevelopmentProblemStatement
Frictionaggregateisthecostly,premieraggregateproductinthemix.
Earlyresearchassessedthecoarsefrictionaggregateindependentofthemix.
Specificationcriteriaarebasedonconservativeengineeringjudgmentfromalimitednumberoffieldtrials.
Frictionstudiesrequirelengthyfieldtrails
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NCATThreeWheelPolishingDevice
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Motor
Counter
PneumaticTires
Load
HMASlabWaterTank
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PreparingMixSlabs
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TestProtocol• Testtworeplicateslabs• 0-0.5-1-2-5-10-20-40-60-100Kcumulativepolishingcycles
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DynamicFrictionTester(DFT)• Testsconductedatspecific
intervalsduringpolishing
(0,0.5,1,2,5,10….100kcycles).
• Threereplicatemeasurements.
• Frictionvaluesaremeasuredat
0,20,40,60and80km/h.
• TestProcedureASTME1911
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DFTOutput
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UseofTestTrackMixturesFHWA Friction Study - Test Track Field Performance
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10
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60
0
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2,000
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4,000
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Test Track Loading (ESALs)
SN40
E1 2003 TN hard W7 2000 AL soft N4 2003 AL hard W3 2003 SC soft
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FrictionRankingBasedonLab&TrackResults
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0 20000 40000 60000 80000 100000 120000 140000
Avg
DFT
60-9
1# lo
ad -
60 r
pm sp
eed
Conditioning Cycles
E1 Mix N4 Mix W3 Mix W7 Mix
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10
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60
0 2,000,000 4,000,000 6,000,000 8,000,000 10,000,000
SN64
Test Track Loading (ESALs)
E1 Mix N4 Mix W3 Mix W7 Mix
Mix TypeRanking based on
Laboratory Results
Test Track Results
E1 1 1W7 2 2N4 3 3W3 4 4
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LabandTestTrackDataCorrelationMix Type Model
ANOVA Table R-square, %
Pearson's Correlation Coefficient F-Statistic P-value
E1 mix SN64 = 20.3 + 0.582 DFT60 59.34 0.016 96.7 0.984 W7 mix SN64 = -4.6 + 0.878 DFT60 7.93 0.106 79.9 0.894 N4 mix SN64 = -0.3 + 0.927 DFT60 2.65 0.245 57.0 0.755 W3 mix SN64 = -44.0 + 1.97 DFT60 2.00 0.293 50.0 0.707
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MSDOTStudyObjective
UsetheNCATrapidlaboratoryfrictionevaluationtestprotocolwiththeTWPDconditioningandDFTtestingdevicestobetterunderstandtheinfluenceoffrictionaggregateinatypicalgravel-limestone9.5mmsurfacemixtureandinanultra-thinsurfacemixture(4.75mm).
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9.5mmMixtureandAggregateSubstitutions
1. Identify9.5mmmixture• 65%crushedgravel(50%+No.8)• 24%limestone(8%+No.8)• 10%sand
2. Determinethecoarseaggregatesubstitutions(+No.8)• 33%&60%slag• 33%&60%granite
3. Screenthesourcegradationsforblending(splitonNo.8)4. PreparethreereplicatetestslabsofeachmixwithPG67-22
bindercompactedto7%airvoids
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9.5mmMixtureResults- DFT
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Ultra-thinMixtureandAggregateSubstitution
1. Identifyultra-thinmixture• 70%limestone• 10%naturalsand• 19%manufacturedsand
2. Determinethetotalaggregatesubstitutions• 25%&50%crushedgravel
3. Screenthesourcegradationsforblending(splitonNo.16)4. PreparethreereplicatetestslabswithPG67-22binder
compactedto7%airvoids
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Ultra-thinMixtureResults- DFT
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HFSTResearchProgram Lab-1Study(8aggregates)
TWPDconditioning,DFT/CTMmeasurements
FieldStudy(8aggregates,extendedfor3aggrs) TestTracktruckconditioning DFT/CTMmeasurements SkidTrailermeasurements
Lab-2Study(4aggregates) Aggr Size?#8,some#6 TWPDconditioning,DFT/CTMtesting BritishPendulum Micro-Deval,AIMS
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LabPolishing
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W9F- Taconite,MNW9E– Al-FeOxide,ORW9D– Slag,PAW9C– Silica,OHW9B– Basalt,WAW9A– Chert,OKW8B– Bauxite,ChinaW8A– Granite,WI
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Testvariation• SMAmixes• Asphaltbindercomparison• PFCmixes
TestTrackFriction Results
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Thankyou.Questions?