optimized mix design for performance · 2020-01-30 · optimized make the best or most effective...
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OptimizedMixDesignforPerformance
NORTHEAST ASPHALT USER PRODUCER GROUP (NEAUPG) ANNUAL MEET ING
BURL INGTON, V ERMONT
OCTOBER 2015
SHANE BUCHANAN
OLDCASTLE MATER IALS
� NeedforanOptimizedMixDesign(OMD)Approach� Proposedframework� Nextsteps
DiscussionTopics
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� Optimized� Makethebestormosteffectiveuseof(a
situation,opportunity,orresource):� Balanced
� Beinginproperarrangementoradjustment,proportion
� OptimizedMixDesign� Optimizethemixintermsofbinder
content+othermixitems(aggregate,grading,recycle,binder,etc.)toprovideneededperformance.
OptimizedorBalancedMixDesign
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� Problems:¡ Drymixesexistinsomelocations¡ Continuingtoincreasebinderreplacementwithout
addressingmixperformanceisnotsustainable
� Solutions:¡ Recognize(admit)performanceissuesrelatedto
drymixes¡ Increaseunderstanding ofthefactorswhichdrive
mixperformance¡ Startthinkingoutsideoflongheld“rulesand
constraints”
¡ Innovate!
WhytheNeedforaNewMixDesignApproach?
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� Eachday,approximately1.4MilliontonsofHMAareproducedintheU.S.(M-Fproductionbasis)
� Equivalentto~2500lanemiles@12’wideand1.5”thick� DistancefromNewYorktoLasVegas
StepsMustbeTakenNow TowardsSolutions
Longtermresearchiscertainlyneeded,butwemusttakestepsNOW towardsasolution
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� Superpavesystemisbecomingunrecognizable
� Statespecificationsarechangingrapidlyasagenciessearchforwaystoimprovedurability¡ Loweringgyrations¡ IncreasingVMA¡ Loweringairvoids¡ Minimumfilmthickness
¡ Minimumbindercontent¡ Limitingrecycle¡ SofterPGbinders¡ Rejuvenators
� Establishingtrue“causeandeffect”isimpossible
AgenciesAreSearchingforSolutions
GOAL:AppropriateEffectiveBinderVolume(Vbe)fortheGivenMixandApplication
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State GyrationLevel1
NewMexico 75,100,125NewYork 50,75,100
NorthCarolina 50,65,75,100Ohio 65Oklahoma 64-22(50),70-28(60),and76-28(80)Oregon 65,80,100
Pennsylvania 50,75,100RhodeIsland 50Tennessee 65or75MarshallTexas 50Utah 50,75,100,125Vermont 50,65,80Virginia 65
Washington 50,75,100,125WestVirginia 50,65,80,100
State GyrationLevel1
Alabama 60Arkansas 50,75,100,125Colorado 75,100Connecticut 75,100
Florida 50,65,75,100
Idaho 50,75,100,125Iowa 50,60,65,68,76,86,96,109,126Kansas 75,100Kentucky 50,75,100Maine 50,75Massachusetts 50,75,100Michigan 45,50,76,86,96,109,126
Minnesota 40,60,90,100Mississippi 50,65,85
Missouri 50,75,80,100,125Montana 75Nebraska 40,65,95
Nevada UseHveemNewHampshire 50,75NewJersey 50,75
� Ndesignvarieswidelyw/levelsbeingreducedwiththeintent ofgainingmorebinder� Problem: Lowergyrationsdonotnecessarilyequatetomorebinder
AgenciesareSearchingforSolutions:Ndesign
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� AlabamaDOT¡ Ndesign=60gyrationsforallmixes¡ IncreaseddesignVMAby0.5%¡ Minimumtotalbindercontentfornon-RASandRASmixes(0.2%higher)¡ 3.5%designvoidsforRASmixes
AgenciesareSearchingforSolutions
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EnhancingtheDurabilityofAsphaltPavements
� “VolumeofEffectiveBinder(Vbe)istheprimarymixturedesignfactoraffectingbothdurabilityandfatiguecrackingresistance.“
� “Anumberofstatehighwayagencieshavedecreasedthedesigngyrationlevelsinanattempttoincreaseeffectivebindercontents.However,decreasingthedesigngyrationsmaynotalwaysproducemixtureswithhigherVBE.
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MixDesignApproaches- Balanced
� BalancedMixDesignApproachesarecurrentlyutilizedbysomeAgencies¡ Texas(Hamburg+OT)¡ Louisiana(Hamburg+SCB)¡ NewJersey(APA+OT)
� Questions¡ Istheutilizedbalancedapproachdesignappropriateforall
mixes?÷ 1)Areuniversalvolumetrics(e.g.,VMAandairvoids)controllingwithoutregardtotraffic?¢ Sameairvoidsforallmixes¢ SameVMAforaNMSmixregardlessoftraffic
÷ 2)Aretheutilizedperformancetestsappropriatefortheprobablemodeofdistress?
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1890•BarberAsphaltPavingCompany•Asphaltcement12to15%/Sand70to83%/Pulverizedcarboniteoflime5to15%
1905
•CliffordRichardson,NewYorkTestingCompany•Surfacesandmix:100%passingNo.10,15%passingNo.200,9to14%asphalt•Asphalticconcreteforlowerlayers,VMAterminologyused,2.2%moreVMAthancurrentdaymixesor~0.9%higherbindercontent
1920s
•HubbardFieldMethod(CharlesHubbardandFrederickField)•Sandasphaltdesign•30blow,6”diameterwithcompressiontest(performance)asphalticconcretedesign(ModifiedHFMethod)
1927
•FrancisHveem(Caltrans)•Surfaceareafactorsusedtodeterminebindercontent;Hveemstabilometerandcohesionmeterused•Airvoidsnotusedinitially,mixesgenerallydrierrelativetoothers,fatiguecrackinganissue
1943
•BruceMarshall,MississippiHighwayDepartment•RefinedHubbardFieldmethod,standardcompactionenergywithdrophammer•Initially,onlyusedairvoidsandVFA,VMAaddedin1962;stabilityandflowutilized
1993
• Superpave• Level1(volumetric)• Level2and3(performancebased,butnever implemented)
HistoryofMixDesign
http://asphaltmagazine.com/history-of-asphalt-mix-design-in-north-america-part-2/
BINDER
CONTENT
LOWER
Stability
Stability+Durability
Stability+Durability
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� Largelyrecipedriven(specified)¡ Aggregates¡ Blendgrading¡ Volumetrics(Va,VMA,VFA,D/A,etc.)¡ PGbindertypeandminimumamount¡ RAPand/orRAScontent¡ Otheradditives (e.g.WMA)use,amount,etc.
� Whilethismaywork,thereareproblems¡ Recipespecificationshavebecomeconvolutedandconfounded
÷ Specifieditemscompeteagainsteachother÷ Newrequirementsgetaddedandnothinggetsremoved
¡ Innovationhasbecomestifledwithourknowledgeoutpacingspecifications
ConventionalMixDesign
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� Let’sstopusingarecipeto“bakethecake”.¡ Definethedesiredproduct
(performance)andopenuptherecipetomeettheendresult.
¡ Whatdefinesagoodcake?GoodTaste¡ Whatdefinesagoodmix?Performance
� OptimizedMixDesignApproachFoundationalPoints¡ “UseWhatWorks”¡ “EliminateWhatDoesn’t”¡ “BeSimple,Practical,andCorrect”
OptimizedMixDesign:ABetterApproach
“GoodDoesn’tHavetobeComplicated”
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� Moveawayfromthephilosophyof“puttingaslittlebinderinthemixaspossiblejusttolimitcracking”
OptimizedMixDesignApproach– BasicFundamentals
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OptimizedMixDesignOverview
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� Challengehistorical/conventionalthinking� Openthemixdesigntoinnovationandengineering� Rewardinnovativeandproactivecontractors
¡ Let’savoidthe“nocontractorleftbehind”system� Greatlylimitthe“rulesandrestrictions”forthemixdesigner
� OBTAINANDMAINTAINPERFORMANCE
OptimizedMixDesignApproach– MindsetChange
Item Thoughts/QuestionsRecycle Doesthemixsuddentlybecomebadat1%overthe"limit"?BlendGrading Arethegradingbandsbasedonperformanceoropinion?Aggregate Canweuselocalaggregatesthatmayperformwell?PGBinder Doweneedtobumpgradesasoften?Polymeruse?Volumetrics Whatissosacredabout4percentairvoids?
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OptimizedMixDesiGnApproach(OMEGA)
I• MaterialEvaluationandSelection
II• MixtureStabilityPerformanceEvaluation
III• MixtureCracking/DurabilityPerformanceEvaluation
IV• MixtureWorkabilityEvaluation
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� Strongemphasisonusinglocalmaterials,maximizingrecycle,andengineeringthebindertoobtainthenecessaryperformance¡ Betterunderstanding/controlofmaterialproperties(e.g.,virgin
aggregategradingconsistency,RAPaggregategravityandrecycledbindercontinuousgrading)
¡ WMAandrejuvenatorusewhereappropriate¡ Binderblendinganalysistoevaluateneededgradesforlocations
OptimizedMixDesignApproach– MaterialsSelection
100.05.1154
15.016.031.0
48.451.633.25PASS
AchievedPGLowTemperature,C -16.5DesiredPGLowTemperature,C -16.0
PassorFail
BINDERBLENDINGANALYSIS
%BRfromRAS%BRTotal(Actual)%ofTotalBRfromRAP%ofTotalBRfromRAS%BRTotal(Allowable)
Maximum%RAPAllowed(100%RAPBR)Maximum%RASAllowed(100%RASBR)Desired%RAP(WeightofTotalMix)Desired%RAS(WeightofTotalMix)%BRfromRAP
Pass
Fail
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� Estimatethetargeteffectivebindervolume(Vbe)basedonNMASandtrafficlevel� AdjustvirginbindercontentasafunctionofRAPandRASadditiontocompensateforlack
of100%recycledbindercontribution� UtilizeM323VMArequirement forrequiredhighvolumemixVbe� IncreasetheVbeby0.5and1.0%formediumandlowvolumetrafficrespectively.
¡ 0.2%Vbe~0.1%Pbe
� Ultimately,selectappropriateVbebasedonmixperformance
OptimizedMixDesignApproach– BinderEstimation
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� Assumption:90and70%,respectivelyoftheRAPandRASbindereffectivelycontributestothetotalmixbinder.
� AdditionalVirginBinder%=0.005(RAP%)+0.055(RAS%)¡ Isthiscorrect?Nooneknows!
÷ 20%RAPor2%RAS=+0.10%VirginBinder÷ TypicalRAP/RASAddition
¢ 17%RAP/4%RAS=+(0.085+0.22)=+0.31%
RecycleBinderAdjustment
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20%RAPComparison(100%and90%BinderContribution)
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RAPSavingsImpact
� Lostsavings($0.50/ton)fromusing90%effectiveRAPbindercontributioncanberecoveredbyusingarelativelysmallamountmoreRAP.¡ 23%vs20%inthisexample.¡ 23%@90%contribution=
$5.52comparedto$5.30(20%at100%contribution)
$4.80 50.0 55.0 60.0 65.0 70.0 75.0 80.0 85.0 90.0 95.0 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0015 2.10 2.29 2.48 2.66 2.85 3.04 3.23 3.41 3.60 3.79 3.9816 2.24 2.44 2.64 2.84 3.04 3.24 3.44 3.64 3.84 4.04 4.2417 2.38 2.59 2.81 3.02 3.23 3.44 3.66 3.87 4.08 4.29 4.5118 2.52 2.75 2.97 3.20 3.42 3.65 3.87 4.10 4.32 4.55 4.7719 2.66 2.90 3.14 3.37 3.61 3.85 4.09 4.32 4.56 4.80 5.0420 2.80 3.05 3.30 3.55 3.80 4.05 4.30 4.55 4.80 5.05 5.3021 2.94 3.20 3.47 3.73 3.99 4.25 4.52 4.78 5.04 5.30 5.5722 3.08 3.36 3.63 3.91 4.18 4.46 4.73 5.01 5.28 5.56 5.8323 3.22 3.51 3.80 4.08 4.37 4.66 4.95 5.23 5.52 5.81 6.1024 3.36 3.66 3.96 4.26 4.56 4.86 5.16 5.46 5.76 6.06 6.3625 3.50 3.81 4.13 4.44 4.75 5.06 5.38 5.69 6.00 6.31 6.6326 3.64 3.97 4.29 4.62 4.94 5.27 5.59 5.92 6.24 6.57 6.8927 3.78 4.12 4.46 4.79 5.13 5.47 5.81 6.14 6.48 6.82 7.1628 3.92 4.27 4.62 4.97 5.32 5.67 6.02 6.37 6.72 7.07 7.4229 4.06 4.42 4.79 5.15 5.51 5.87 6.24 6.60 6.96 7.32 7.6930 4.20 4.58 4.95 5.33 5.70 6.08 6.45 6.83 7.20 7.58 7.9531 4.34 4.73 5.12 5.50 5.89 6.28 6.67 7.05 7.44 7.83 8.2232 4.48 4.88 5.28 5.68 6.08 6.48 6.88 7.28 7.68 8.08 8.4833 4.62 5.03 5.45 5.86 6.27 6.68 7.10 7.51 7.92 8.33 8.7534 4.76 5.19 5.61 6.04 6.46 6.89 7.31 7.74 8.16 8.59 9.0135 4.90 5.34 5.78 6.21 6.65 7.09 7.53 7.96 8.40 8.84 9.2836 5.04 5.49 5.94 6.39 6.84 7.29 7.74 8.19 8.64 9.09 9.5437 5.18 5.64 6.11 6.57 7.03 7.49 7.96 8.42 8.88 9.34 9.8138 5.32 5.80 6.27 6.75 7.22 7.70 8.17 8.65 9.12 9.60 10.0739 5.46 5.95 6.44 6.92 7.41 7.90 8.39 8.87 9.36 9.85 10.3440 5.60 6.10 6.60 7.10 7.60 8.10 8.60 9.10 9.60 10.10 10.60
RAPSavings(Binder+Aggregate)"WhatIf"Table- RAPEff.BinderCont.NetSavings EffectiveBinderContributionFromRAP,%
RAP,%
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� MixCompaction(KeyPoints)¡ Utilizeasinglegyrationlevelused(e.g.,lockingpoint),~60to75gyrationsistypical¡ Lock,DON’Tcrushtheaggregate!¡ Compactspecimensfourbindercontents(Vbemin,Vbemin-0.50,Vbemin- 1.0,
Vbemin+0.50)÷ Recordspecimenvolumetricsandproceedtoperformancetesting
OptimizedMixDesignApproach– Compaction
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� Utilizeoneofseveralavailable“rutting”evaluationtools.¡ Hamburg,APA,AMPTFlowNumber,etc.¡ Failurecriteriabasedonbestavailableresearch(local,
regional,ornational)÷ Specificcriteriaasafunctionoftraffic(e.g.,low,medium,high)
OptimizedMixDesignApproach– StabilityEvaluation
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� Durability/crackingevaluationissubstantiallymorecomplicatedthanstability¡ Whatisthemodeofdistress?¡ Whatistheagingcondition?
� Crackingpredictionisaknown“weak”linkinperformancetesting¡ Nogeneralconsensusonwhatisthebest
testortheappropriatefailurethreshold� GOALS
¡ MATCHTHETESTTOTHEDISTRESS¡ SETAPPROPRIATEFAILURETHRESHOLDS
OptimizedMixDesignApproach– Durability/CrackingEvaluation
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MatchtheTesttotheDistress
From:LouayMohammad,LTRC
• DiscShapedCompactTension
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MatchtheTesttotheDistress
From:DaveNewcomb,TTINEAUPGAnnualMeeting2015
� NCHRP9-57:ExperimentalDesignforFieldValidationofLaboratoryTeststoAssessCrackingResistanceofAsphaltMixtures
� CrackingWorkshopheldinearly2015� Toptestsforvariousdistressesidentifiedbynationalgroupof
academia,agency,andindustryrepresentatives
� Cantabrotestcanprovideaveryquick,lowcostdurabilitymeasurement¡ Relative indicationofmixdurability¡ Almosttooeasynottotry!
� SpecimeninLAdrum,nospheres,300revolutions
AlternateDurabilityTest/Check- Cantabro
From:IssacHoward,SEAUPG2014
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� LimitedresearchavailableonCantabrotestingofdensegrademixes� Researchperformedonmixesfromvariousairfieldprojects
� Analyzedvariablesweregradation,bindertype,plantproducedvs.labproducedmix,aggregatesource,airvoidcontentandconditioning.
� Resultsfollowed“expected”trends:¡ Massloss(ML)increasedwithVaincrease¡ MLdecreasedwithpolymermodifiedbinders¡ MLincreasedw/coarsergradings¡ MLincreasedw/aging
CantabroTesting– DenseGradedMixes
From:“PerformanceorientedguidanceforairfieldasphaltpavementswithintheSuperpavecontext”,RobertJames,PhDDissertation,MississippiStateUniversity,August2014
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CantabroTesting– NCATTestingofFHWAALFMixes
From:
� 2013FHWAALFexperimentalmixeswereevaluatedwithseveral“practicaltests”.
� Cantabrowasabletostatisticallydifferentiatethevirginmixfromanyotherexperimentalmix.
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DesignPerformanceCurves– PossibleBinderRangeExample
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RuttingThreshold
CrackingThreshold
� Performancetestingcanhelpguidemiximprovement(optimization)
� ExampleshowsHamburg+DCT,butotherstability+durability/crackingtestcanbesubstitutedw/sameapplication
MixPerformanceSpaceDiagram
From:Dr.BillButtlar,UniversityofIllinois
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ThePathForward
� Mustcontinuewiththeoreticalresearch/modelingefforts,butnotbeafraidtoutilizepracticalapproachestofindsolutions.
� Weneedtomoveincrementallyintheappropriatedirection tolimitriskofmixperformanceissue.
� FHWAMixETGTaskGroupformed(September2015)todefinethecurrentstateof“BalancedMixDesign”approachesandofferguidanceforBMDuse.
� Recognizethatthisisalongtermeffortwithups/downs,butwemuststartnow.
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ShaneBuchananAsphaltPerformanceManagerOldcastleMaterialsCompanyshane.buchanan@oldcastlematerials.com205-873-3316
ThoughtsandQuestions?
http://www.pennyauctionwatch.com/
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