Week. Student will: Incorporate Force of Friction into calculation Static Friction Kinetic Friction.
Report 17-01 on Friction Aggregates - Auburn...
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i NCAT Report 17-01 EVALUATION OF LABORATORY FRICTION PERFORMANCE OF AGGREGATES FOR HIGH FRICTION SURFACE TREATMENTS By Michael Heitzman Jason Moore January 2017
Transcript of Report 17-01 on Friction Aggregates - Auburn...
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NCATReport17-01
EVALUATIONOFLABORATORYFRICTIONPERFORMANCEOFAGGREGATESFORHIGH
FRICTIONSURFACETREATMENTS
ByMichaelHeitzman
JasonMoore
January2017
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EvaluationofLaboratoryFrictionPerformanceofAggregatesforHighFrictionSurfaceTreatments
NCATReport17-01by
MichaelHeitzman,PhD,PE(WA,IA)
AssistantDirectorPrincipalInvestigator
JasonMoore
LaboratoryManager
NationalCenterforAsphaltTechnologyatAuburnUniversityAuburn,Alabama
January2017
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ACKNOWLEDGEMENTSThisstudywassponsoredbytheMichiganDepartmentofTransportationunderthedirectionofPaulSchiefer,RegionBridgeSupportUnit.TheauthorswouldliketoacknowledgetheeffortsoftheNCATstaffwhoperformedlaboratorytesting.Thestudycouldnotbeaccomplishedwithoutthecontributionsofmaterialsfromthefollowingcompanies.
E-BONDEpoxies,Inc,FtLauderdale,FLRedFlintGroup,EauClaire,WIFlintRockProducts,Commerce,OKFXMinerals,Newell,WVC-EMinerals,Andersonville,GAFairmountMinerals,Chardon,OHWashingtonRock,Graham,WAUSSilica,Mauricetown,NJEarthworksSolutions,Gillette,WY
DISCLAIMER
Thecontentsofthisreportreflecttheviewsoftheauthorswhoareresponsibleforthefactsandaccuracyofthedatapresentedherein.ThecontentsdonotnecessarilyreflecttheofficialviewsorpoliciesoftheMichiganDepartmentofTransportation,theNationalCenterforAsphaltTechnologyorAuburnUniversity.Thisreportdoesnotconstituteastandard,specification,orregulation.Commentscontainedinthispaperrelatedtospecifictestingequipmentandmaterialsshouldnotbeconsideredanendorsementofanycommercialproductorservice;nosuchendorsementisintendedorimplied.
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TABLEOFCONTENTS
LISTOFTABLES........................................................................................................................v
LISTOFFIGURES......................................................................................................................v
LISTOFABBREVIATIONS.........................................................................................................vi
INTRODUCTION/BACKGROUND..............................................................................................1
SCOPEOFSTUDY....................................................................................................................3
TESTPROCEDURE...................................................................................................................4SamplePreparation............................................................................................................4TestProtocol......................................................................................................................4TestResults........................................................................................................................6TestQualityControl............................................................................................................6DataAnalysis......................................................................................................................8
CONCLUSIONSANDRECOMMENDATIONS.............................................................................11
REFERENCES..........................................................................................................................12
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LISTOFTABLES
Table1StudyAggregateTypesandSources.................................................................................4Table2SummaryofDFTResults...................................................................................................7Table3SummaryofCTMResults..................................................................................................7
LISTOFFIGURES
Figure1NCATThreeWheelPolishingDevice...............................................................................2Figure2GenericAsphaltSurfaceFrictionPerformanceCurve.....................................................3Figure3SlabReplicateDFTComparison.......................................................................................8Figure4ComparisonofLaboratoryFrictionPerformance............................................................9Figure5ComparisonofLaboratorySurfaceTexturePerformance...............................................9Figure6CorrelationofFrictionandSurfaceMacrotexture........................................................10Figure7CorrelationofLaboratoryandFieldTerminalFrictionValues(7).................................11
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LISTOFABBREVIATIONS
AASHTO.....................AmericanAssociationofStateHighwayandTransportationOfficialsASTM.........................AmericanSocietyforTestingandMaterialsCTM...........................circulartexturemeterDFT............................dynamicfrictiontesterDFT(40)......................dynamicfrictionmeasuredat40km/hDOT............................DepartmentofTransportationFHWA........................FederalHighwayAdministrationFn...............................frictionnumberHFST..........................highfrictionsurfacetreatmentK................................thousandkm/h..........................kilometersperhourlb................................poundsMDOT........................MichiganDepartmentofTransportationMTD...........................meantexturedepthNCAT..........................NationalCenterforAsphaltTechnologypsi..............................poundspersquareinchrpm............................revolutionsperminuteSN40R........................skidnumberat40mphwithribbedtireTWPD.........................threewheelpolishingdevice
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INTRODUCTION/BACKGROUND
PavementfrictionisonecomponentoftheFederalHighwayAdministration’s(FHWA)RoadwayDepartureSafetyProgramandoneofthetoolsishighfrictionsurfacetreatments(HFST).AnHFSTisanimportantapplicationforcriticalsafetylocationslikebridgedecks,horizontalcurves,andhighspeeddecelerationramps.HFSTusebeganintheearly1950’sintheUSAasathinpolymer-bondedbridgedecktreatment.Theindustrythatinstalledthisproductformanyyearsusedavarietyofaggregatesthattheyfeltperformedwell.TheuseofcalcinedbauxiteastheHFSTaggregatewasfirstpublishedin1976.Atthispoint,theFHWAandAmericanAssociationofStateHighwayandTransportationOfficials(AASHTO)viewHFSTasaspecializedsubsetofthin-bondedpolymeroverlaysforlocationswithcriticalfrictiondemand.Thequestionthatcontinuestobeexaminedistheuseofotherregionallyavailableandlessexpensivefrictionaggregatesthatcanprovidesatisfactoryperformanceasathin-bondedpolymeroverlay.
WhilethisconceptwasbeingsuccessfullyusedinothercountriesforcrashreductionandsimilarproductswerebeingusedintheUSAonbridges,theFHWAOfficeofPavementTechnologyinitiatedtheSurfaceEnhancementsatHorizontalCurvesprogramtodemonstratetheapplicationofHFSTinroadwaycurves.Whenthedemonstrationprogrambegan,AASHTOhadnotwrittentheguidespecificationforHFSTandcompaniesthatbidthedemonstrationprojectsoftenbidtheirthinpolymer-bondedbridgedecktreatmentsystems,whichdidnotalwaysincludecalcinedbauxite.
FHWA,AASHTO,andtheAmericanTrafficSafetyServicesAssociation(ATSSA)havedevelopedanHFSTguidespecification(PP79-14StandardPracticeforHighFrictionSurfaceTreatmentforAsphaltandConcretePavements).Currently,theguidespecificationonlyrecognizescalcinedbauxiteaggregate(1,2).Therefore,theAASHTOdefinitionforHFSTrequirescalcinedbauxite.
TheMichiganDepartmentofTransportation(MDOT)hasspecialprovision12SP-800A-03forHFST,anditspecifiestheuseofcalcinedbauxite(3).TheDepartment’sspecialprovision12SP-712B-01forthinepoxypolymerbridgedeckoverlayspecifiesaggregatepropertiesandincludesalistofsixapprovedsuppliers(4).
Comparativefieldfrictiontestingofalternativeaggregatesforthinpolymer-bondedbridgedecktreatmentsystemsisnotpractical.Theidealtestsiterequiresasinglelocationandthelengthofeachtestsectionmustaccommodateconsistentlockedwheelskidtrailertestinganduniformtrafficabrasion.Thereareveryfewsitesthatwouldmeetthesecomparativetestingcriteria.Ifmultiplesitesareneeded,itisdifficulttofindsiteswithsimilartraffic,climate,andwintermaintenance.
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TheNationalCenterforAsphaltTechnology(NCAT)ThreeWheelPolishingDevice(TWPD),asshowninFigure1,offersapracticalandtechnicallysoundcontrolledevaluationofalternativefrictionaggregates.Thelabevaluationisnotatruefieldtrafficexaminationofperformance,butthemethodpermitsadirectcomparisonofalternativeaggregatesbyapplyinguniformlycontrolledconditioningandtesting.
Figure1NCATThreeWheelPolishingDevice
Figure2depictsagenericpavementfrictionperformancecurveforanasphaltpavement.Theearlyportionoffrictionperformanceexhibitsadramaticincreaseinfrictionastheasphaltbinderfilmwearsoffthepavementsurfacefollowedbyasteepfrictionlossduetoinitialaggregatepolishing.Aftertheinitialaggregatepolishing,thesurfacefrictionperformancestabilizesasdefinedbylong-termfrictionlosstrend,commonlycalledterminalfriction.Whenathinepoxypolymersurfaceisplacedonanexistingpavementorbridgedeck,thereisnoasphaltfilmonthenewsurface,sothesurfacebeginswithitspeakfrictionvalue.Thisstudyfocusedonthelong-termfrictionlosstrend(terminalfriction)ofeachaggregate.
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Figure2GenericAsphaltSurfaceFrictionPerformanceCurve
SCOPEOFSTUDY
Forthepurposesofthisstudy,thetermsbauxiteandHFSTareusedgenericallyanddonotfullyagreewiththerecentlyadoptedAASHTOstandardpractice(PP79-14)discussedintheIntroduction.Whilethetermbauxitereferstoanaturalaggregatewithrelativelysoftproperties,inthisreport,calcinedbauxitewillbesimplyreferredtoasbauxite.Inthisreport,thetermHFSTwillbeusedtodescribetheplacementofathinpolymer-bondedfrictionaggregatesurfacetreatmenttoimprovethefrictionpropertiesofthepavementsurface.Assuch,thetermHFSTdoesnotmeetallthecriteriaofPP79-14.
ThisstudywasadirectcomparisonofelevenaggregatesappliedasHFSTusinganNCATlaboratoryevaluationprocess.TheuseoftheTWPDforsurfacefrictioncomparisonsinthelaboratoryisananalysisprocessthatisstilldeveloping.Sincetherearenospecifiedstandardsorthresholdsforfrictionvalues,thistestprocedureallowsengineersandresearcherstomakerelativecomparisonsoffrictionperformancebetweensurfaces.Itwillbetheresponsibilityofgoverningagenciestodeterminewhatanacceptablethresholdshouldbe.
ThescopeofthelaboratorystudywastoprovideMDOTwithfrictionperformancedatafordeterminingwhichaggregatesourcesmettheagency’scriteriaforHFST.Theobjectivewastoevaluatethefrictionperformanceofelevenaggregatesusingidenticalconditioning(polishing)withtheNCATTWPD.ThedescriptionandsourceoftheaggregatesaregiveninTable1.Testingeachaggregateforspecificationcompliancewasnotapartofthestudy.Eachaggregatesample,asreceived,wasexpectedtomeetthinepoxypolymerbridgedeckoverlaycriteria.
MeasurementVariation
TemperatureImpactVariation
Frictio
n
CumulativeTraffic
Long-termFrictionLossTrend
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Table1StudyAggregateTypesandSources
AggregateName/AggregateType
Location Supplier Supplier’sOfficeLocation
Basalt EauClaire,WI RedFlintGroup EauClaire,WICopperSlag EauClaire,WI RedFlintGroup EauClaire,WIFlint65-8 Picher,OK FlintRockProducts Commerce,OKRKBauxite6x14Ccalcinedbauxite Newell,WV FXMinerals Newell,WV47-4x20calcinedkaolin Roswell,GA C-EMinerals Andersonville,GA60-4x20calcinedkaolin Roswell,GA C-EMinerals Andersonville,GA70-4x20calcinedkaolin Roswell,GA C-EMinerals Andersonville,GABestSand612quartz Chardon,OH FairmountMinerals Chardon,OHArmorStonequartz KingCreekPitOrting,WA WashingtonRock Graham,WAEP5-Modquartz Frederick,MD USSilica Mauricetown,NJTractionControlFeldsparmineral Gillette,WY EarthworksSolutions Gillette,WY
TESTPROCEDURE
SamplePreparation
The11HFSTaggregateswereplacedon20x20inchasphalttestslabs.Tworeplicateslabsweremadeforeachaggregate.Theasphaltsurfacesofthe22slabswerecleanedusingalightsand-blastspraytoremovethesurfaceasphaltfilm.Toensureagoodbondbetweentheaggregateandepoxy,eachaggregatesamplewaswashedtoremovedustandovendried.Theepoxybondingagent,E-BOND526,wasappliedtothesurfaceofeachslabatanapproximaterateof0.04gal/sqftandspreaduniformlywithanotched-toothtrowel.Theaggregatewasbroadcastedbyhandontotheuncuredepoxysurface.Aftertheepoxycuredfor24hours,thesurfacewasswepttoremovelooseaggregate,aggressivelyrubbedwithawoodenboardtodislodgelooselyboundaggregate,andsweptagain.
TestProtocol
ThelaboratoryprotocolfortheNCATTWPDisadevelopingprocedure.TheNCATTWPDwasinitiallydevelopedatNCATina2004-2006study(5).Asecondstudycompletedin2010refined
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thetestparametersandfoundareasonablecorrelationbetweenlaboratoryresultsandfieldtests(6).TheTWPDisdesignedtouniformlycondition(polish)a284mmdiameterpathonthesurfaceofatestslab.
TheconditionedpathistestedbyASTMtestmethodsE2157(StandardTestMethodforMeasuringPavementMacrotexturePropertiesUsingtheCircularTrackMeter)andE1911(StandardTestMethodforMeasuringPavedSurfaceFrictionalPropertiesUsingtheDynamicFrictionTester),commonlycalledthecirculartexturemeter(CTM)anddynamicfrictiontester(DFT),respectively.TheCTMandDFTareusedformeasuringthesurfacetextureandfrictionofpavementsurfaces.Bothtestmethodscanbeusedinthelaboratoryorinthefield.TheCTMmeasuresthepavementsurfacemacrotextureprofileandprovidesameanprofiledepth(MPD)inmillimeterstoquantifythemacrotexture.TheDFTmeasurespavementsurfacefrictionpropertiesasafunctionofspeed(20,40,and60km/hforthisstudy)andprovidesadimensionlessvaluecalledthefrictionnumber(Fn).ThereisnoconsistenttrendthathigherDFTspeedmeasureshigherfriction,sothespeedthatproducesthemostrepeatablemeasure,40km/h,wasusedfortheentirestudy.Inthisreport,theDFTfrictionvaluesarecommonlyexpressedasDFT(40),meaningtheFnat40km/h.Forbothtestprocedures,increasingvaluesindicatehighersurfacefrictioncharacteristics.
FortheevaluationofHFSTaggregatesinthislaboratorystudy,thefollowingtestprotocolwasused.
• ThetworeplicateslabsofeachHFSTaggregateweredividedforconditioningonseparateTWPDunits.
• AnewsetofthreeTWPDtireswasinstalledforeachslabtested.TheTWPDwasoperatedat60rpm,50psitirepressure,and91lbgrosscarriageweight.PreviousstudiesusingtheTWPDshowedthat80,000to100,000(80Kto100K)conditioningcycleswereneededtoreachaterminalsurfacefrictioncondition.Thisstudyextendedthepolishingto140Kcyclestohelpdistinguishperformancebetweenthehigherqualityaggregates.
• EachCTMtestincludedthreereplicatemeasurementsonthedryslabsurface.Atemplatewasplacedovertheslabtoensurethemeasurementsweretakenatthesamelocation.
• EachDFTtestincludedthreereplicatemeasurements.Atemplatewasplacedovertheslabtoensurethemeasurementsweretakenatthesamelocation.DFTrubbersliderpadswerereplacedaftereverysixmeasurements.AlthoughtheASTMstandardallowstherubbersliderstobeusedfortwelvemeasurements,theaggressivewearonHFSTsurfacesrequiresmorefrequentreplacement.
• ThesequenceofDFTtestingandNCATTWPDconditioningwasasfollows:
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1. Onepairofslabswaspreparedfortestingandconditioning.2. InitialCTMandDFTmeasurementsweretakenoneachslab.3. TWPDconditioningfor70Kcycleswasperformedoneachslab.4. Theslabsweredriedovernight.5. CTMandDFTmeasurementsweretakenoneachslab.6. Anadditional70Kcyclesofconditioningwasperformedforeachslabmatching
thesameTWPDandslab.7. Theslabsweredriedovernight.8. FinalCTMandDFTmeasurementsweretaken.9. Thetestprotocolsequencewasrepeatedforeachsetofslabs.
TestResults
TheDFTmeasurementsarelistedinTable2andCTMmeasurementsarelistedinTable3.
TestQualityControl
Laboratorytestingconsistedof99setsofDFTmeasurements(threecycleperiods,threemeasurementspeeds,andelevenmaterials).TestingqualitycontrolexaminedthedifferencebetweentheDFTmeasurementsofthereplicateslabstodetermineifthetwoslabsforeachHFSTaggregategeneratedsimilarresults.Forexample,theaverageDFT(40)resultsfrom70KcyclesofTWPDforslab1werecomparedtothesameresultsforslab2.Differencesbetweentheslabmeasurementswerecombinedintoahistogramtoshowthedistributionofslabtestdifferences,showninFigure3.Overall,theaveragedifferencewasaDFTdeltaof0.034.Twostandarddeviationsfromthemeanwas0.08andonlythreedeltavaluesweregreaterthantwostandarddeviations.ThosevaluesarehighlightedinTable2.ThosetestvaluesrepresentinitialDFTtestsonunconditionedsurfacesandarenotcriticaltotheanalysis.
TheresultsofthisqualitycontrolanalysisweresimilartoanearlierHFSTstudypresentedinNCATreport15-04.Thatstudyobservedthat65%oftherangeswerebelow0.040and98%werebelow0.120.
CTMmeasurementsareveryrepeatable.Noqualitycontrolevaluationwasperformedonthedata.
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Table2SummaryofDFTResults
Table3SummaryofCTMResults
#Cycles km/h Slab1-Avg Slab2-Avg Slab1-Avg Slab2-Avg Slab1-Avg Slab2-Avg Slab1-Avg Slab2-Avg20 0.60 0.54 0.78 0.82 0.90 0.94 0.72 0.7240 0.62 0.55 0.81 0.88 0.95 0.97 0.75 0.7760 0.68 0.58 0.87 0.95 0.94 1.05 0.80 0.8320 0.50 0.52 0.55 0.56 0.78 0.81 0.54 0.4940 0.53 0.51 0.57 0.59 0.77 0.79 0.58 0.5360 0.51 0.55 0.57 0.61 0.74 0.79 0.64 0.5720 0.48 0.52 0.55 0.55 0.79 0.81 0.50 0.5040 0.52 0.52 0.57 0.56 0.79 0.80 0.53 0.5360 0.51 0.54 0.56 0.59 0.77 0.82 0.56 0.54
#Cycles km/h Slab1-Avg Slab2-Avg Slab1-Avg Slab2-Avg Slab1-Avg Slab2-Avg Slab1-Avg Slab2-Avg20 0.82 0.80 0.81 0.77 0.84 0.79 0.87 0.8240 0.86 0.82 0.84 0.80 0.86 0.79 0.85 0.8160 0.92 0.86 0.87 0.80 0.89 0.84 0.85 0.8120 0.62 0.61 0.60 0.59 0.58 0.55 0.59 0.6640 0.64 0.63 0.64 0.63 0.60 0.58 0.61 0.6760 0.66 0.66 0.66 0.61 0.65 0.59 0.63 0.7020 0.57 0.54 0.58 0.54 0.57 0.54 0.51 0.5740 0.60 0.58 0.60 0.57 0.59 0.57 0.52 0.5760 0.64 0.61 0.65 0.58 0.63 0.56 0.53 0.60
#Cycles km/h Slab1-Avg Slab2-Avg Slab1-Avg Slab2-Avg Slab1-Avg Slab2-Avg20 0.69 0.64 0.60 0.62 0.77 0.7840 0.70 0.67 0.62 0.66 0.80 0.8160 0.72 0.73 0.66 0.69 0.80 0.8220 0.45 0.44 0.41 0.43 0.51 0.5440 0.48 0.49 0.43 0.45 0.55 0.5760 0.51 0.50 0.45 0.49 0.57 0.6220 0.41 0.43 0.41 0.39 0.47 0.5140 0.45 0.46 0.43 0.41 0.47 0.5460 0.48 0.49 0.47 0.44 0.50 0.53
Basalt FlintRock-Flint RKBauxite CopperSlag
TractionControl
0cycles
70,000cycles
140,000cycles
0cycles
70,000cycles
140,000cycles
47-4x20 60-4x20 70-4x20 ArmorStone
0cycles
70,000cycles
140,000cycles
BestSand EP5MOD
Basalt FlintRock-Flint RKBauxite CopperSlag 47-4x20 60-4x200cycles 2.09 2.38 1.97 2.14 2.88 1.8170Kcycles 1.82 1.64 1.35 1.57 1.79 1.62140Kcycles 1.67 1.65 1.39 1.44 1.76 1.55
70-4x20 ArmorStone BestSand EP5MOD TractionControl0cycles 2.30 1.83 2.22 1.65 1.6270Kcycles 1.33 1.53 1.33 1.45 1.54140Kcycles 1.29 1.40 1.35 1.50 1.49
allvaluesareMTD(mm)
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Figure3SlabReplicateDFTComparison
DataAnalysis
Theanalysisfocusedontheterminal(70Kand140Kcycles)frictioncharacteristicsofthehighfrictionsurfaces,includingthechangeinvaluesbetweenthe70Kand140Kmeasurementincrement.Thecomparisonofthechangeintestmeasurementsbetween70Kcyclesand140Kcyclesisparticularlyimportanttodetermineiftheaggregatereachedaterminalfrictioncondition.Figure4displaystheDFTfrictionresultsforallaggregatestested.Figure5displaystheCTMmacrotextureresultsforallaggregatestested.TheCTMsurfacetexturedatashowsallsurfaceswithMTDmacrotextureintherangeof1.2to1.8mm,whichiscommonforHFSTafterconditioning.Incomparison,typicalconventionaldense-gradeasphaltmixtureshaveterminalmacro-texturebelow0.60mmandporousmixturesarebelow1.2.Figure6displaysthe140KterminalDFTfrictionandCTMsurfacetextureterminalvaluesfortheelevenaggregates.Similartopreviousstudies,thereisnocorrelationbetweenmeasuredfrictionandsurfacemacrotextureforHFSTsurfaces.
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Figure4ComparisonofLaboratoryFrictionPerformance
Figure5ComparisonofLaboratorySurfaceTexturePerformance
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Figure6CorrelationofFrictionandSurfaceMacrotexture
ThelegendinFigure4placestheaggregatesinorderfromhighestfrictionafter140KpolishingcyclestolowestfrictionbasedonDFT(40)values.Fromthesummaryofthefrictiontesting,thefollowingobservationsaremade.
• Calcinedbauxitemaintainshigherfrictionthanallotheraggregatesinthestudy.• AllthreeproductsfromRoswell,GAandFlintRockdisplayedsimilarhighperformance
comparedtootheraggregates(exceptbauxite).• ArmorStonecontinuedtopolishbetween70Kcyclesand140Kcycles.Basedon140Kcycle
ranking,itfallsintoamiddlecategory,butat70Kcyclesitwasperforminginahighercategory.
• CopperslagandTractionControlshowedsimilarmiddlecategoryfrictionperformance.• Basaltdisplayedconsistentfriction,losingminimalfrictionperformancefrom0cyclesto
140Kcycles.TheaggregatehaslessangularitypriortopolishingasnotedbythelowDFT(40)at0cycles,buthasverygoodpolishresistanceasshownbytheminimalfrictionlossafterpolishing.
• BestSandandEP5MODdemonstratedthelowestfrictionperformance.
BasedonapreviousFHWAstudyonHFSTfriction,laboratoryterminalfrictionvaluesarehigherthanfieldterminalfrictionvalues,asshowninFigure7(7).UsingtheFHWAstudy’scorrelation,theexpectedterminalfieldfrictionwouldbeapproximately40(SN40R)fortheRoswellproductsandFlintRock.
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Figure7CorrelationofLaboratoryandFieldTerminalFrictionValues(7)
CONCLUSIONSANDRECOMMENDATIONS
Thisstudycomparedthelaboratoryperformanceof11differentfrictionaggregatespreselectedbytheagency.ThestudyfocusedonlaboratorytestmeasurementsthatresembleaterminalfrictionconditionafterpolishingwiththeNCATThreeWheelPolishingDevice.Thefriction,measuredbytheDynamicFrictionTester,hasawiderangefrom0.40to0.80,indicatingthattherewasasubstantialdifferenceinfrictionperformancebetweenaggregates.Themacrotexturerange,measuredasmeantexturedepth,wascommonforHFSTafterconditioning.TherewasnocorrelationbetweenmeasuredfrictionandsurfacemacrotextureforHFSTsurfaces.
ItistheresponsibilityofthegoverningagencytodetermineanacceptablethresholdforHFSTperformance.Thesuccess(reductionincrashes)oflocallyplacedsectionswithregionallyavailablefrictionaggregatemaybeanappropriateapproachforsettingacceptablematerialthresholds.
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REFERENCES
1. EveryDayCounts:ReportontheEDC2Summits.FHWA,U.S.DepartmentofTransportation,2013.
2. HighFrictionSurfaceTreatmentsFrequentlyAskedQuestions.ReportFHWA-CAI-14-019.FHWA,U.S.DepartmentofTransportation,2014.
3. MichiganDepartmentofTransportation.SpecialProvisionforHighFrictionSurfaceTreatment.12SP-800A-03.http://mdotcf.state.mi.us/public/dessssp/spss_source/12SP-800A-03.pdf.
4. MichiganDepartmentofTransportation.SpecialProvisionforThinEpoxyPolymerBridgeDeckOverlay.12SP-712B-01.http://mdotcf.state.mi.us/public/dessssp/spss_source/12SP-712B-01.pdf.
5. Vollor,T.,D.Hanson.DevelopmentofLaboratoryProcedureforMeasuringFrictionofHMAMixturesPhaseI.NCATReport06-06.NationalCenterforAsphaltTechnology,Auburn,Ala.,2006.
6. Erukulla,S.RefiningaLaboratoryProceduretoCharacterizeChangeinHot-MixAsphaltSurfaceFriction.MSthesis.AuburnUniversity,Auburn,Ala.,2011.
7. Heitzman,M.,P.Turner,M.Greer.HighFrictionSurfaceTreatmentAlternativeAggregatesStudy.NCATReport15-04.NationalCenterforAsphaltTechnology,Auburn,Ala.,2015.
