Semi-CircularBendingBeamTest:EffectofLoadingandMixParameters

MansourSolaimanian,XuanChen,PennsylvaniaStateUniversity

AnnualMeeting,October19,2017

2

Outline

• AReviewofAsphaltConcreteFatigueTests

• Semi-CircularBeam(SCB)Test

• PSUSCBStudyandPreliminaryResults

• Summary

3

Outline

• AReviewofAsphaltConcreteFatigueTests

• Semi-CircularBeam(SCB)Test

• PSUSCBStudyandPreliminaryResults

• Summary

MonotonicTests• IndirectTensile• Semi-CircularBeam• Disk-ShapedCompactTension

CyclicTests• FourPointBendingBeam• IndirectTensile• UniaxialPush-Pull• TexasOverlay

PictureCurtesy:IPCGlobal,Umass,PennState

LabScaleTests

LabScaleTests(CyclicTests) Fatigue/CantileverTrapezoid

TexasOverlayTester

BendingBeam

6

ModelScaleAcceleratedTests• ThirdScaleModelMobilLoadSimulator(MMLS3)

7

TestTracksandFullScaleTests

PictureCurtesy:NCAT

PennStateTrack

NCATTrack

…andALF,HVS,MLS,….

8

Outline

• AReviewofAsphaltConcreteFatigueTests

• Semi-CircularBeam(SCB)Test

• PSUSCBStudyandPreliminaryResults

• Summary

9

BackgroundonSCB

• EarlyWorkonRocks(ChongandKuruppu,1984)

• IntroducingSCBforAsphaltTesting(Molenaar,2000&

2002)

• FurtherResearch(Mohammadetal.,2004)- LA

• FurtherResearch– IFIT(Alqadi etal.,2015)- IL

• ImplementationinSpecs(Mohammadetal.,LTRC,2016)

10

SCBTestApplyonRocks(InitialApplication)

PhotoSource:Limetal.1984

11

SCBTestAppliedtoRocks

PhotoSource:DynamicBehaviorofMaterials,Vol.1SCBTestingofGraniteRock

12

SCBTestAppliedtoRocks

PhotoSource:AdvancesinMaterialsScienceandEngineeringVol.2014,Article814504

Compression-InducedFractureSurfacesandFailureMechanism

13

SCBTestSetupAppliedLoad

Support Support120mm

150mm

Notch

SpecimenThickness:50 mmNotchDepth:15 mmNotchWidth:1.5 mm

14

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 1 2 3 4 5 6 7 8

Load

(N)

Displacement(mm)

Slope@InflationPoint(m)

Slope@50%PeakLoad

CriticalDisplacement

ParametersUsedForEvaluation

WorkofFracture(W")

PeakLoad(P$%&)

FI = A×G"

abs(m)G" =

W"B 4 L

FractureEnergy FlexibilityIndex

B:SpecimenThicknessL:LigamentLength

A:Constant

StiffnessIndexSlope@50%PeakLoadinPre-PeakCurve

15PlotSource:Mohammadetal.2012

NotchDepth:

25.4 mm

NotchDepth:

31.8 mm

NotchDepth:

38.0mm

LouisianaSCBMethod(JIntegralConcept)

StrainEnergytoFailure

16

PlotSource:Elseifietal.2012

LouisianaSCBMethod(JIntegralConcept)

𝐽7 = −1𝑏𝑑𝑈𝑑𝑎 =

𝑈>𝑏>−𝑈?𝑏?

1𝑎? − 𝑎>

Where:𝐽7 =Criticalstrainenergyreleaserate,KJ/m2;b=Specimenthickness,m;a=Notchdepth,m;andU=Strainenergytofailure,kN-morKJ.

thickness:50mmmultiple-notchdepths(25.4/31.8/38mm)

𝑱𝒄 :slopeofthenotchdepthvs.strainenergyplot

17

AdvantagesofSCBTest

• SpecimenEasilyPreparedUsingSGCorFieldCores

• FourSpecimensfromOneCompactedMix

• EasytoPerformandSimpletoAnalyze

• PossibleToPerformTestUsingMarshall-TypeStabilityTester

• GoodCorrelationtoFieldPerformance??

18

CurrentIssues

• WhatTestParameterstoUse?

• Whattesttemperature?

• Howfasttotest?

• Whatpass/failcriteria?

• SensitivitytoMixParameters

• Short-termagedorlong-termagedmix?

• Testrepeatabilityandreproducibility?

19

Outline

• AReviewofAsphaltConcreteFatigueTests

• Semi-CircularBeam(SCB)Test

• PSUSCBStudyandPreliminaryResults

• Summary

20

INVESTIGATE

• EffectofTestTemperature

• EffectofLoadingRateRange

• EffectofAging(shorttermvslongterm)

• EffectofBinderContentandBinderStiffness

• EffectofVoids

21

TestTemperatureI-FIT Protocol:FixedTemperatureforAllMixes,i.e.25℃

ProposedProtocol:UsingEffectiveTemperatureConceptNCHRP704:APerformance-RelatedSpecificationforHMA

Freq:LoadingFrequency,Hz;MAAT:MeanAnnualAirTemperature,℉;𝝈MAAT:StandardDeviationoftheMeanMonthlyAirTemperature;Rain:AnnualCumulativeRainfallDepth,inches;Sunshine:MeanAnnualPercentageSunshine,%;andWind:MeanAnnualWindSpeed,Mph.

Harrisburghisaround18℃

22

TestLoadingRate

CurrentProtocol:• 50mm/min(toofast,notenoughdatapoints,higherCOV)• 0.5mm/min(tooslow,affectedbycreep)

Findings:• Loadingratebetween5to20mm/minwillminimizetheeffect

ofcreep,andprovideareasonablerangeforFIforlongtermagedmix.

23

20 mm

50 mm

50 mm

20 mm

150 mm

150 mm

SpecimenPreparation

• SGCSpecimenorFieldCores

• CuttoEnsureMinimumAVGradient

• ObtainDensity

• ConditionSpecimensatTest

Temperature

• ConductTest

ItTakes 3daysfromMixingto

ObtainResults

24

SpecimensAfterCuttingReadyforTesting

SpecimensBefore(L)/After(R)Testing

25

0

500

1000

1500

2000

2500

3000

3500

0 1 2 3 4 5 6 7 8

Load

(N)

Displacement(mm)

TypicalLoadvsDisplacementCurves3Replicates,PG58-28,25°C

25mm/min

5mm/min

1 mm/min

50mm/min

26

Temperature/LoadingRateEffects

0500

100015002000250030003500400045005000

VirginAgg+P

G58+

7AV

VirginAgg+P

G58+

4AV

VirginAgg+P

G58+

7AV+

5.9B

C

VirginAgg+P

G76+

7AV

VirginAgg+P

G58+

7AV@18C

VirginAgg+P

G58+

4AV@18C

VirginAgg+P

G58+

7AV+

5.9B

C@18C

VirginAgg+P

G76+

7AV@18C

FractureEne

rgy(J/

m^2)

FractureEnergyComparison1mm/min 5mm/min 20 mm/min 50 mm/min

Tested@25℃ Tested@18℃

27

05101520253035404550

VirginAgg+P

G58+

7AV

VirginAgg+P

G58+

4AV

VirginAgg+P

G58+

7AV+

5.9B

C

VirginAgg+P

G76+

7AV

VirginAgg+P

G58+

7AV@18C

VirginAgg+P

G58+

4AV@18C

VirginAgg+P

G58+

7AV+

5.9B

C@18C

VirginAgg+P

G76+

7AV@18C

FlexibilityIn

dex

FlexibilityIndexComparison1mm/min 5mm/min 20 mm/min 50 mm/min

Tested@25℃ Tested@18℃

Temperature/LoadingRateEffects

28

StiffnessIndicesofAgedMixes

y = 1.3827x + 1846.5R² = 0.84

0

3000

6000

9000

12000

15000

0 3000 6000 9000 12000 15000

LongTe

rmAged,SI

ShortTermAged,SI

StiffnessIndex

LineofEquality

29

FactureEnergyofAgedMixes

y=0.6063x+811.61R²=0.8137

1000

1500

2000

2500

3000

3500

4000

4500

1000 1500 2000 2500 3000 3500 4000 4500

LongTe

rmAged

FractureEne

rgy(J/

m^2)

ShortTermAgedFractureEnergy(J/m^2)

FractureEnergy

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FIofAgedMixes

0

5

10

15

20

25

30

35

0 5 10 15 20 25 30 35

LongTe

rmAged

FlexibilityIn

dex

ShortTemAgedFlexibilityIndex

FlexibilityIndex1mm/min 5mm/min 20 mm/min 50 mm/min

31

Temperature/LoadingRateSweepinSCB

0

4

8

12

16

20

0 5 10 15 20 25 30 35 40

FlexibilityIn

dex

Temperature(℃)

FlexibilityIndexLongTermAged

1mm/min5mm/min20 mm/min50 mm/min

FasterLoading

32

0

500

1000

1500

2000

2500

3000

0 1 2 3 4 5 6 7 8

Load

(N)

Displacement(mm)

STOA,PG64-22,7%AV

4.7%BC 5.2%BC 5.7%BC 6.2%BC

PostPeakSlope

EffectofBinderContent

33

EffectofBinderContent

0

10

20

30

40

50

60

4 4.5 5 5.5 6 6.5 7

FlexibilityIn

dex

BinderContent(%)

7%AirVoid

PG58-28 PG64-22 PG76-22

34

EffectofBinderContent

0

5

10

15

20

25

30

35

4 4.5 5 5.5 6 6.5 7

FlexibilityIn

dex

BinderContent(%)

4%AirVoid

PG58-28 PG64-22 PG76-22

35

0

500

1000

1500

2000

2500

3000

0 1 2 3 4 5 6 7 8

Load

(N)

Displacement(mm)

STOA,7%AV,5.2%BC

PG58-28

PG64-22

PG76-22

EffectofBinderGrade(Stiffness)

36

EffectofBinderGrade(Stiffness)

0

10

20

30

40

50

60

52 58 64 70 76 82

FlexibilityIn

dex

BinderHighTemperatureGrade

7%AirVoid

4.7%BC 5.2%BC 5.7%BC 6.2%BC

37

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 2 4 6 8

Load

(N)

Displacement(mm)

TypicalLoadvs.DisplacementCurveSTOA,PG64-22,5.2%BC

2%AV

4%AV

7%AV

EffectofAirVoid

38

EffectofAirVoid

0

5

10

15

20

25

30

35

40

45

50

0 1 2 3 4 5 6 7 8 9 10 11 12

FlexibilityIn

dex

AirVoid(%)

5.2%BinderContent

PG58-28 PG64-22 PG76-22

39

TheEffectofAirVoidReportedbyUIUC

Source:Maxwell2016

40

TheEffectofAirVoidReportedbyUIUC

Source:Maxwell2016

41

CRMMixes– PeakLoad(LTOA)

42

0

200

400

600

800

1000

1200

1400

1600

1800

2000

FractureEne

rgy(J/

m2 )

PG64+22 PG58-28+10%CRM

CRMMixes– FractureEnergy(LTOA)

43

CRMMixes– FlexibilityIndex(LTOA)

0

1

2

3

4

5

6

7

8

9

10

FlexibilityIn

dex

PG64+22 PG58-28+10%CRM

44

Outline

• AReviewofAsphaltConcreteFatigueTests

• Semi-CircularBeam(SCB)Test

• PSUSCBStudyandPreliminaryResults

• Summary

45

Summary

• Higher loading rate Lower FI• Higher temperature Higher FI• Higher Binder Content Higher FI• Higher Air Void Higher FI?• Higher Aging Lower FI• Increase in Binder Stiffness (Grade)?• CRM+PG 58 higher FI compared with

PG 64

October17,2017

Thankyou!

October18,2014