optimized mix design for performance · 2020-01-30 · optimized make the best or most effective...

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

NEAUPGAnnualMeeting2015

� 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?

NEAUPGAnnualMeeting2015

� 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/

NEAUPGAnnualMeeting2015