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Exploring the Compactability and Workability ofRAPElizabeth Poblete

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ExploringtheCompactabilityandWorkabilityofRAP

ExploringtheCompactabilityandWorkabilityofRAP

AnHonorsThesissubmittedinpartialfulfillmentoftherequirementsforHonorsStudiesin

CivilEngineering

By

ElizabethPoblete

2019DepartmentofCivilEngineering

CollegeofEngineeringTheUniversityofArkansas

iv

ACKNOWLEGEMENTS

Thisresearchwouldnotbepossiblewithoutthesupportfromthefollowing:

SadieCasillas,UniversityofArkansasDr.AndrewBraham,UniversityofArkansasArkansasDepartmentofHigherEducation

UniversityofArkansasDepartmentofCivilEngineeringUniversityofArkansasHonorsCollege

v

TABLEOFCONTENTS

ACKNOWLEDGEMENTS..................................................................................................................IV

TABLEOFCONTENTS.......................................................................................................................V

LISTOFTABLES...............................................................................................................................VI

LISTOFFIGURES.............................................................................................................................VI

EXPERIMENTALDESIGN..................................................................................................................1

INTRODUCTION...........................................................................................................................1OBJECTIVES..................................................................................................................................4MATERIALSANDMETHODS.........................................................................................................4SAMPLECALCULATIONS..............................................................................................................8

RESULTSANDDISCUSSION............................................................................................................10

COMPACTION............................................................................................................................10DIRECTSHEAR...........................................................................................................................13

CONCLUSION.................................................................................................................................15

REFERENCES..................................................................................................................................17

vi

LISTOFTABLES

TABLE1:MATERIALMATRIX...........................................................................................................4

TABLE2:EXPERIMENTALPLAN.......................................................................................................4

TABLE3:RAPGRADATION...............................................................................................................5

TABLE4:CALCULATEDCOMPACTIONVALUES..............................................................................11

TABLE5:DIRECTSHEARTESTVALUES...........................................................................................13

LISTOFFIGURES

FIGURE1:RAPGRADATION.............................................................................................................5

FIGURE2:SAMPLESINPROTECTIVEMOLDSSTOREDATROOMTEMPERATURE...........................6

FIGURE3:SAMPLELOADEDINTOTESTINGAPPARATUS................................................................8

FIGURE4:TESTINGAPPARATUSUNDERLOADINGRAM.................................................................8

FIGURE5:COMPACTIONCURVE...................................................................................................11

FIGURE6:AVERAGEWEIVALUESWITHERROR............................................................................12

FIGURE7:AVERAGEDIRECTSHEARVALUESWITHERROR...........................................................14

1

EXPERIMENTALDESIGN

INTRODUCTIONTheuseofasphaltmaterialshasbecomeastandardpracticeintheconstructionof

pavementsaroundtheworld.Traditionalhotmixasphaltpavementsaremadeofasphalt

concrete,whichisacombinationofaggregateandasphaltbinderthatisheated,mixed,and

placedontheroadway.Inthepast50years,theuseofcoldin-placerecycling(CIR)ofasphalt

concretepavementshasbecomeaprominentalternativeinpavementrehabilitation(Cox,

2015).Insteadofremovingandreplacingdistressedpavement,CIRcaneliminatesignificant

distressesinpavementsbyrecyclingthein-placematerial,reducingcostsandemissionsfrom

haulingvirginmaterialtothejobsite.

CIRisaprocessbywhichexistingasphaltconcretepavementsarepartiallyreclaimed,

mixedwithadditives,placed,andcompacted(Cox,2015).Existingasphaltconcretepavementis

removed,crushed,andgradedtoobtainproperaggregatesizes.Thisnewmaterialisreferredto

asreclaimedasphaltpavement,orRAP.ThebinderinCIRisasphaltemulsion.Emulsionsconsist

ofasphaltsuspendedinwaterandtheydonotrequiretheadditionofheatinorderto

adequatelycoattheRAP(Cox,2015).AfterincorporationofasphaltemulsionwithRAP,the

mixtureisplacedbackonthesurface.Themixtureiscompactedandadditionalsurfacecourse

constructionmaybeperformedbeforethestructurallysoundpavementisreadytobere-

opened.ItisimportanttonotethattheuseofCIRisnotappropriateinallcircumstances,

specificallyinareaswithsubstantialfrostaction,unstablesubbaseorsubgrade,orwhenthe

bondbetweenasphaltandaggregatehasbeenbrokenintheexistingpavement(Cox,2015).

Inherently,CIRisanefficientrehabilitationsystemforasphaltconcretepavements.

Sinceexistingpavementsaremilled,remixed,andplaced,thereislittletonowasteplacedinto

landfills.In1999,Oklahomaproduced200,000tonsofpavementmillings,which,ifnotrecycled,

wouldbelandfilled(Issa,2001).Inadditiontoreducingthewastesenttolandfills,CIRis

2

economicallyviable.In1993,itwasestimatedthatCIRsaved$10,000perkilometeras

comparedtocompletepavementreconstruction(Cox,2015).

Inadditiontoasphaltemulsion,Portlandcementorothercementitiousmaterialscan

beusedtoincreaseperformanceofCIR.Previousstudieshaveexaminedtheuseof

supplementarycementitiousmaterials(SCM)andtheireffectonstrengthandstabilityofCIR

pavements.SCM’saredefinedas“aninorganicmaterialthatcontributestothepropertiesofa

cementitiousmixturethroughhydraulicorpozzolanicactivity,orboth”(ASTM,2016).The

purposeofusinganSCM’s,suchasPortlandcement,istoreducecost,accountfordifferent

requiredcharacteristics,ortochangeunitweight,forexample(Somayaji,2001).A1999study

examinedtheuseofhydratedlimeasanSCMwithasphaltemulsionandindicatedanincreased

unitweight,tensilestrength,andresilientmodulus(Cross,1999).Theseresultsopenedthedoor

tousingSCM’sinordertoachievegreaterstrengthinCIR.Twoyearslater,astudywas

performedtocharacterizeCIRpavementswithRAPboundwithasphaltemulsionandPortland

Cement.ItwasfoundthatPortlandcementincreasedHveemstabilitywhiledecreasingthe

amountofasphaltemulsionnecessarytobindRAP(Issa,2001).In2015,differentratiosof

emulsionsandSCM’swereexaminedtodeterminethebestbalancetoachieveoptimalstrength

characteristics.Itwasfoundthatsinglecomponentbindersystems(SCB),oronethatuses

asphaltonlyasabinder,hadan“excessreservecapacity”toonetypeofdistresswhilehaving

“insufficientcapacity”toanotherdistress(Cox,2015).Balancingamultiplecomponentbinder

system(MCB)allowsCIRpavementstohaveadequatecapacitytoresistseveraltypesof

distresses,althoughthisisnotalwayseconomical(Cox,2015).Whiletherehasbeenagreat

efforttocharacterizetheeffectofSCM’sonhardenedpropertiesofCIRpavements,therehas

beenlimitedefforttocharacterizetheeffectofSCM’sonthecompactabilityandworkabilityof

CIR.

3

Compactabilityis“theeffortrequiredtoachieveconsolidationofasphaltconcrete”

(Braham,etal.,2015).Workabilityis“therelativeeasewithwhichasphaltconcretecanbe

mixed,handled,andplaced”(Braham,etal.,2015).Compactabilityandworkabilityare

quantifiedbyvaluessuchasworkabilityenergyindex(CIR-WEI),compactabilityenergyindex

(CIR-CEI),compactiondensificationindex(CIR-CDI),andtrafficdensificationindex(CIR-TDI).CIR-

WEIvaluesindicatetheenergyrequiredtocompactasampleto76%Gmm,orN76.CIR-WEIvalues

areinverselyrelatedtotheenergyrequiredtocompactasample(YeungandBraham,2018).

CIR-CDIvaluesindicatetheareaunderthedensificationcurvefromN8totheN76(Yeungand

Braham,2018).CIR-CDIvaluesaredirectlyrelatedtotheenergyrequiredtocompactasample,

meaningthatasCIR-CDIvaluesincrease,sodoestheenergyrequiredtocompactasample.CEI

andTDIvalueswerenotconsideredinthisresearch.

Compactabilityandworkabilityarecharacteristicsthathavebeengreatlystudiedinhot

mixasphaltandwarmmixasphalt,buthavenotbeenexploreddeeplyinCIR.Withthe

increasinguseofCIRinpavementrehabilitation,studyingcompactabilityandworkabilityofCIR

isimportantbecauseitmayrevealmoreefficientconstructionmethodsoramoreeconomical

approachestoCIR.BecauseofthepropertiesdemonstratedbyCIRpavementscontainingSCM,

exploringthecharacteristicsofcompactabilityandworkabilitywillleadtoabetter

understandingoftheeffectsofSCM’sinCIR.

4

OBJECTIVESTheprimaryobjectivesofthisresearchweretoinvestigatethecompactabilitycharacteristicsof

RAPusingMCBapproachandtodeterminetheeffectofanMCBapproachonworkabilityoflab

createdRAP.

MATERIALSANDMETHODSForthisexperimentalplan,36testswererunon18sampleswith6differentmixtures.The

materialsarelistedinTable1andtheexperimentalplanislistedinTable2.Themixdesignfor

anasphaltemulsionstabilizedCIRmixturewasdeterminedforRAPsampledfromalocalquarry.

ThegradationofRAPsamplesmaybefoundinTable3,withagraphicalrepresentationinFigure

1.ThemixdesignwascompletedaccordingtheAASHTOPP86-17andAASHTOMP31-17.In

ordertoisolatetheinfluencesofthetwoasphaltemulsionsandthetwoSCM’s,thesame

mixtureproportionsandRAPsourcewereusedforallsamples.

Table1:MaterialMatrix

Factor Level

EmulsionTypeCMS-1(Proprietary)CMS-1(Commodity)

SCM(0.5%byweight)

TypeIPortlandcementTypeCflyash

NoSCMEmulsionContent 2.75%(basedonmixdesign)

Table2:ExperimentalPlan

Variable NumberofOptions Options

EmulsionType 2ProprietaryCommodity

SCM 3Portlandcement

FlyashNoSCM

TestingApparatus 2SuperpaveGyratory

CompactorDirectShear

5

Table3:RAPGradation

SieveSize %Passing RAPSample(g)1/2 100% 03/8 96% 104#4 63% 858#8 45% 468#16

- 1170

#30#50#100#200PANTotal 2600

12.50

9.50

4.75

2.36

1.18

0.60

0.30

0.150

0.0750

20

40

60

80

100

%Passing

ParticleSizeDistribution- mm

AvgBurnGradation

BulkGradation

WashGradation

Figure1:RAPGradation

6

SamplePreparationMethods:RAPsampleswerebatchedandgradedinto(18)2600gsamples,

whichwouldallowsamplestofitinthedirectshearapparatusaswellasconserveRAP.Priorto

sievingandbatching,allRAPmaterialsweredriedinanovenat60°C.Thiscontrolledwater

contentduringthisevaluation.Onedaypriortocompacting,anticipatedfieldwatercontent

(6.8%)wasaddedtosamples,andsampleswereplacedincontainersandcoveredwithplasticto

retainwatercontent.ThiswatercontentwasbasedonthemoisturecontentoftheRAPwhen

receivedfromthequarry,whichmimicsin-situmoisture,aswellasanadditional2.0%bymass

ofwater,whichrepresentstheamountofwaterexpectedtobeaddedduringthemilling

process.

CompactionMethods:RAPsampleswereplacedinabucketmixerandmixedfor30seconds

beforethespecificSCMwasadded,thenmixedforoneminute.Emulsionwasslowlyadded

whilemixing,thenmixedforoneadditionalminute.Inthecaseofsampleswhichreceivedno

SCM,samplesmixedforoneminuteaftertheadditionofemulsion.Throughoutmixingofall

samples,aspoonwasusedtoensureuniformcoatingoftheRAP.Uponthecompletionof

mixing,sampleswerefunneledintoSuperpavegyratorycompactormolds,placedinthe

Superpavegyratorycompactorandcompactedto30gyrations.Aftercompaction,sampleswere

removedfromthecompactor,placedinprotectivemoldsthatallowedforairflow,andplaced

intoa60°Coventocurefor48hours.After48hours,fullycuredsampleswereremovedfrom

theovenandstoredatroomtemperatureuntilfurthertestingwascompleted,asseeninFigure

2.

Figure2:Samplesinprotectivemoldsstoredatroomtemperature

7

BulkSpecificGravityMethods:Bulkspecificgravityvalueswereobtainedaccordingtothe

Corelok®method,AASHTOT331-13(2017).Afterovencuringandstorageatroomtemperature,

sampleswereweighed.Sampleswereplacedinvacuumsealbags,sealed,thenweighed.

Sampleswerethenplacedinaslinginawaterbath,andwereweighed.Sampleswereremoved

fromthewaterbath,removedfromvacuumsealbags,thenweighedtoensurenowater

infiltratedthevacuumbag.Inthecasethatwaterdidinfiltratethebag,sampleswereplaced

backintheirprotectivemoldsandallowedtodryoutatroomtemperatureforatleast24hours

beforebulkspecificgravitywasrepeated.Bulkspecificgravitywascalculatedusingrecorded

weights.Samplecalculationsmaybefoundinthecalculationssectiontofollow.

DirectShearTestMethods:Thedirectsheartestmimicsahotmixasphaltbondstrengthtest

andisbeingevaluatedforuseinquantifyingstrengthgainofasphaltemulsionCIRmixtures.

Thistestisperformedona22-kiploadframewitha5-kiploadcell.Inordertoloadthesample

intothetestingapparatus,alevelingblockwasplacedunderonesideofthedirectshearcasing

toensurethesamplewasplacedperpendiculartotheshearingforce,asseeninFigure3.The

topofthedirectsheartestingapparatuswasplacedontopofthesampletocreateafullcasing

aroundthecircumferenceofthesample.Thelevelingblockwasremoved,andtheentiretesting

apparatuswithsamplewerecenteredundertheloadingramintheloadframe,asseeninFigure

4.ModeledaftertheMarshallStabilitytest,a2inchperminuteloadratewasselected,withthe

loadappliedatthemidpointofthesampleuntilfailure.

8

SAMPLECALCULATIONS

BulkSpecificGravity,GMB

VARIABLE SIGNIFICANCE FORMULA SAMPLECALCULATION–PE_01

A Wt.ofDryCoreinAirbeforetesting,g -- 2641.0

B Wt.ofSealedCoreinAir,g -- 2687.2

C WtofSealedCoreinWater,g -- 1289.1

D

Wt.ofDryCoreinAiraftertesting,g -- 2641.1

E BagWeight,g E=(B-A) E=2687.2-2641.0

E=46.2

F BagRatio F=A/E

F=2641.0/46.2F=57.165

G LargeBagVolumeCorrection G=(-0.00166*F+0.8596) G=(-0.00166*57.165+0.8596)

G=0.765

H TotalVolume H=(E+D)–C

H=(46.2+26441.1)-1289.1H=1398.2

I BagVolume I=E/G

I=46.2/0.765I=60.4

J SampleVolume J=H–I

J=1398.2-60.4J=1337.8

K BulkSpecificGravity(Gmb) K=A/J

K=2641.0/1337.8K=1.974

LCheck:%wt.change

(mustbe-0.08%to+0.04%)

L=(A-D)/A*100% L=(2641.0-2641.1)/2641.0*100%=0.0%

TheoreticalMaximumSpecificGravity,GMM

CalculationofGMMwasoutsidethescopeofthisproject.GMMwasassumedtobe2.372basedonprevioustestingaccordingtoAASHTOT-209-12(2016).

Figure3:Sampleloadedintotestingapparatus

Figure4:Testingapparatusunderloadingram

9

PercentGMMAchievedThroughCompaction,%GMM

VARIABLE SIGNIFICANCE FORMULA SAMPLECALCULATION–PE_01

%GMM PercentGMMachievedthroughcompaction %𝐺𝑀𝑀 =

𝐺𝑀𝐵𝐺𝑀𝑀

∗ 100% %𝐺𝑀𝑀 =1.9742.372

∗ 100%%𝐺𝑀𝑀 = 83.2%

WorkabilityEnergyIndex,CIR-WEIVARIABLE SIGNIFICANCE FORMULA SAMPLECALCULATION–PE_01

CIR-WEI WorkabilityEnergyIndex

𝐶𝐼𝑅 −𝑊𝐸𝐼

=𝜋𝑑r4 ∗ 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒 ∗ (ℎyz{ − ℎ|})

𝑁|}

𝐶𝐼𝑅 −𝑊𝐸𝐼 =𝜋0.15r4 ∗ 599.2 ∗ (90 − 85.6)

2

𝑊𝐸𝐼 = 23.3

ShearStrengthVARIABLE SIGNIFICANCE FORMULA SAMPLECALCULATION–PE_01

𝜏 ShearStrength 𝜏 =𝑃𝑒𝑎𝑘𝐿𝑜𝑎𝑑(𝑙𝑏)

𝐴𝑟𝑒𝑎 𝜏 =

3861.88𝑙𝑏𝜋 ∗ 3𝑖𝑛r

𝜏 = 136.59𝑝𝑠𝑖

10

RESULTSANDDISCUSSION

CompactionUsingdatacollectedduringsamplecompactionintheSuperpaveGyratoryCompactor

CIR-WEIwerecalculatedforeachsample.Samplecalculationsmaybefoundinthesample

calculationsection.Sincesampleswerecompactedtoasetnumberofgyrationsratherthanto

aspecific%GMM,CEIandTDIwerenotabletobecalculated,sincethetarget%GMMforCEIand

TDIwerenotachievedin30gyrations.

Table4includesfinalvaluesusedinanalysisandcalculations.Figure5offersagraphical

representationoftheaveragecompactioncurveforeachsampletype.Itisnotedthatthe

presenceofSCM’sresultedinanincreased%GMM,asseeninthecurvesthatareshiftedup

relativetosamplesthatcontainedemulsiononly.Thisshiftupindicatesthesampleswere

compactedtoahigherdensitywithfewergyrations,thusindicatingamoreeasilycompacted

mixture.ItisseeninFigure5thatsamplesreached76%GMMbefore8gyrations,soCDI

calculationscouldnotbeperformed.

11

Table4:CalculatedCompactionValues

Characteristic SampleName Gmm Gmb Final%Gmm WEI WEISt.Dev AveragePressure

(kPa)

EmulsionOnly

CE_01 2.372 1.995 84.1 23.8

0.551

599.4

CE_02 2.372 1.993 84.0 24.4 599.1

CE_03 2.372 1.977 83.3 24.9 599.2

PE_01 2.372 1.974 83.2 23.30.354

599.2

PE_02 2.372 2.016 85.0 23.8 599.1

Average 1.991 83.9 24.04 599.2

EmulsionandFlyAsh

CE_FA_01 2.372 2.025 85.4 23.8

0.346

599.3

CE_FA_02 2.372 1.980 83.5 24.4 599.2

CE_FA_03 2.372 2.012 84.8 24.4 599.3

PE_FA_01 2.372 2.024 85.3 23.8

0.289

599.2

PE_FA_02 2.372 2.014 84.9 23.8 599.1

PE_FA_03 2.372 2.012 84.8 23.3 599.3

Average 2.011 84.8 23.9 599.233

EmulsionandPortlandCement

CE_PC_01 2.372 2.092 88.2 21.7

1.848

599.9

CE_PC_02 2.372 2.091 88.1 21.7 599.9

CE_PC_03 2.372 2.057 86.7 24.9 599.2

PE_PC_01 2.372 2.028 85.5 20.7

1.343

599.5

PE_PC_02 2.372 1.983 83.6 22.8 599.3

PE_PC_03 2.372 1.994 84.1 21.7 599.4

PE_PC_04 2.372 1.992 84.0 23.8 599.3

Average 2.034 85.7 22.5 599.5

Figure5:CompactionCurve

70

72

74

76

78

80

82

84

86

88

90

0 5 10 15 20 25 30

%Gmm

NumberofGyrations,N

%GmmandNProprietaryEmulsionOnly

CommodityEmulsionOnly

ProprietaryEmulsion+FlyAsh

CommodityEmulsion+FlyAsh

ProprietaryEmulsion+PortlandCement

CommodityEmulsion+PortlandCement

12

Figure6offersadirectcomparisonforaverageCIR-WEIvaluescalculatedforeach

sampletype.Errorbarswereincludedtorepresenterroramongsamples.Comparingaverage

valuesonly,itappearsthatsamplescontainingflyashbehavedsimilarlytosamplescontaining

emulsiononly.Sincesamplescontainingflyashandsamplescontainingemulsiononlyhad

increasedCIR-WEIcomparedtosamplescontainingPortlandcement,lessenergywouldbe

requiredforplacingandcompaction.But,whenconsideringaveragevaluesanderror,itdoes

notappearthattherewasasignificantdifferenceinCIR-WEIvaluesamongsampletypes.

Figure6:AverageCIR-WEIvalueswitherror

Sincetherewasnosignificantchangeinworkability,itmaybenotedthattheuseof

SCM’smaybejustified.Previousstudieshaveshownperformancebenefitsduetothepresence

ofPortlandcementsuchasearlystrengthgainandresistancetomoisturedamage(Cox,2015).

0

5

10

15

20

25

30

ProprietaryEmulsionOnly

CommodityEmulsionOnly

ProprietaryEmulsion+FlyAsh

CommodityEmulsion+FlyAsh

ProprietaryEmulsion+Portland

Cement

CommodityEmulsion+Portland

Cement

WEI

CIR-WEIResults

13

Additionally,previousstudieshaveshownperformacebenefitsduetothepresenceofflyash

suchasearlyruttingandravelingprevention(Thomas,et.al,2000).

DirectShear Usingdatacollectedfromdirectsheartests,directshearstrengthwascalculatedfor

eachsample.Samplecalcultionsmaybefoundinthesamplecalculationssection.Table5

includesfinalvaluesusedincalculationsandanaylsis.Figure7offersadirectcomparisonof

averagedirectshearstrengths.Itappearsthatdirectshearstrengthsarenotsignificantly

differentforeachsampletype.Thelackofsiginificantdifferencemaybeduetothecuringtime

ofsamples.Samplescuredforover30daysbeforedirectsheartestingcouldbeperformed.

Benefitsofanadmixutresuchasflyasharemostnoteableinearlystages(Thomas,et.al,2000).

Table5:DirectShearTestValues

DirectShearTestSampleID PeakLoad(lb) ShearStrength(psi) St.Dev.(psi)CE_01 3529.44 124.83 -CE_02 3575.93 126.47 -CE_03 3835.03 135.64 -CE_Avg 3647 128.98 5.82CE+FA_01 4092.53 144.74 -CE+FA_02 3928.69 138.95 -CE+FA_03 4011.10 141.86 -CE+FA_Avg 4011 141.85 2.90CE+PC_01 3816.56 134.98 -CE+PC_02 3905.35 138.12 -CE+PC_03 3578.56 126.57 -CE+PC_Avg 3767 133.22 5.98

PE_01 3861.88 136.59 -PE_02A 2405.33 85.07 -PE_Avg 3134 110.83 36.43PE+FA_01 3538.77 125.16 -PE+FA_02 3474.55 122.89 -PE+FA_03 4279.68 151.36 -PE+FA_Avg 3765 133.14 15.83PE+PC_01 3648.05 129.02 -PE+PC_02 3614.82 127.85 -PE+PC_03 3808.93 134.71 -PE+PC_04A 3868.16 136.81 -PE+PC_Avg 3735 132.10 4.34

14

ProprietaryEmulsionOnly

CommodityEmulsionOnly

ProprietaryEmulsion+Fly

Ash

CommodityEmulsion+FlyAsh

ProprietaryEmulsion+

PortlandCement

CommodityEmulsion+

PortlandCement

0

25

50

75

100

125

150ShearStrength(p

si)

DirectShearTestResults

Figure7:Averagedirectshearstrengthwitherror

15

Conclusions Despiteitseconomicandenvironmentalbenefits,thewidespreaduseofColdIn-Place

Recycling(CIR)iscurrentlyinhibitedbyalackoflaboratorytestingandevaluation,specificallyin

theareasofcompactabilityandworkabilityofthereclaimedmixturestabilizedwithasphalt

emulsion.ThepurposeofthisstudywastoexploretheinfluenceofadmixturesinCIRusing

modifiedSuperpaveGyratoryCompactor(SGC)compactionmetrics.

ThetestmethodsinthisstudyincludedcompactioninaSuperpaveGyratoryCompactor,

bulkspecificgravityusingtheCorelok®method,anddirectshear.Thesemethodswereselected

tocharacterizecompactability,workability,andshearstrength.Workabilitywasmeasuredusing

themodifiedSGCmetricofCIR-WEI.

Basedoncompactiontesting,therewasnosignificantchangeintheworkabilitymetric

forsamplescontainingSCM’s.Sincenosignificantadverseorbeneficialchangewasnotedin

CIR-WEI,otherstrengthtestsmaybeperformedonRAPsamplescontainingSCM’stodetermine

theadvantagesordisadvantagesofaMCBapproach.ItcanbenotedthatCIR-WEIvaluesinthis

researcharedoublethatofpreviousresearchwithsimilarparameters(YeungandBraham,

2018).

Thestrengthtestperformedinthisstudy,directsheartest,revealedthattheonly

statisticallysignificantdifferenceinstrengthwasbetweensamplescontainingcommodity

emulsiononlyandsamplescontainingcommodityemulsionandflyash.Therewasnosignificant

changeinshearstrengthinallothersamples,indicatingthatdirectshearisnotacharacteristic

thatthepresenceofSCM’simpacts.Furtherexplorationoftheeffectsofadmixtures,suchas

Portlandcementandflyash,onthecompactability,workability,shearstrength,andother

strengthcharacteristicsofMCBCIRwillcontributetothegrowingbodyofknowledge

surroundingCIR.

16

CIRisaninherentlysustainableandeconomicallyviableprocess,sincethereislimited

wasteandreducedmaterialinput.AMCBapproachtoCIRaddsanotherlevelofsustainability,

specificallywhenflyashistheSCM,sinceflyashisawastebyproductofthecoalburning

industry.IncreasedresearchintheareaofCIRwillonlyexpanditsbodyofknowledge,which

mayleadtoincreasedimplementationofsustainable,pavementrecyclingtreatments.

17

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