Investigation of Low Temperature Cracking in Asphalt Pa ......IDT, SCB, and DCT test samples were cut Air void content determined in different study Field cores air void content Cell

Investigation of Low Temperature Cracking in Asphalt Pa ementsCracking in Asphalt Pavements

National Pooled Fund Study – Phase II

Task 2 ReportTask 2 ReportMechanical Testing and Analysis

November 2010

Introduction

Materials

Location Construction date

Binder Grade

Asphalt modifiers

RAP(30%)date Grade modifiers (30%)

MnRoad 33 September 2007 PG 58-34 PPA -MnRoad 34 September 2007 PG 58-34 SBS+PPA -MnRoad 35 September 2007 PG 58-34 SBS -MnRoad 35 September 2007 PG 58-34 SBS -MnRoad 77 September 2007 PG 58-34 Elvaloy+PPA -MnRoad 20 August 2008 PG 58-28 - Non-FractionedMnRoad 21 August 2008 PG 58-28 - FractionedMnRoad 21 August 2008 PG 58 28 FractionedMnRoad 22 August 2008 PG 58-34 - Fractioned

Wisconsin 9.5 mm SMA 2008 PG 64-22 - -NYS Typical Mix 2008 PG 64-22 - -yp

Test samplesLoose mix laboratory compacted (SGC) specimensField cored specimens

Introduction

Participating test laboratoriesUniversity of Minnesota (UMN)University of Illinois Urbana Champagne (UIUC)University of Illinois Urbana Champagne (UIUC)University of Wisconsin (UWM)Iowa State University (ISU)

Fracture Test Methods

Indirect Tensile (IDT)Semi-Circular Bend (SCB)( )Disc-Shaped Compact Tension (DCT)

IntroductionPrimary experimental variables

Test TemperaturePGLT (1)PGLT ( )

PGLT+10°CAir void content

For laboratory specimens: 4% and 7%For laboratory specimens: 4% and 7%For field specimens: assumed to be 7%

Asphalt mixture conditioningNon conditionedNon conditionedConditioned for 5 days @ 85°C (long term aging)Field cores (2 to 3 years old)

Secondary experimental variablesAsphalt modification: PPA, SBS, SBS+PPA, Elvaloy+PPARAP fractioning: Non-fractioned vs Fractioned

(1) PG low temperature limit

RAP fractioning: Non fractioned vs. Fractioned PG low limit: PG 58-28 vs. PG 58-34

Introduction

Laboratory experimental layout

T Mi

MN/Road Test SectionWI NYS33, 34, 35, 20 21 22Test

Device Temp Mix Conditioning

, , ,77 20, 21, 22

Air Voids, %4 7 4 7 4 7 4 7

PGLT None xxx xxx xxx xxx xxx xxx xxx xxx

SCB

PGLT None xxx xxx xxx xxx xxx xxx xxx xxxPGLT+10ºC None xxx xxx xxx xxx xxx xxx xxx xxx

PGLT 5 days@85ºC xxx xxx xxx xxxPGLT Field cores xxx xxx xxx xxx

DC(T)


PGLT 5 days@85ºC xxx xxx xxx xxxPGLT Field cores xxx xxx xxx xxxPGLT Field cores xxx xxx xxx xxx

IDT


PGLT 5 days@85ºC xxx xxx xxx xxx

* Shadowed cells indicate the data missing from the experimental layout

PGLT Field cores xxx xxx xxx xxx

Experimental workPreparation of laboratory test specimens

All SGC compaction at UMNHalf of the 7% air voids cylinders were long termed agedHalf of the 7% air voids cylinders were long termed agedIDT, SCB, and DCT test samples cutCylinders and samples distributed to UIUC and UWM

Non-conditioned specimens used at UMN

Experimental work

Non-conditioned specimens used at UIUC

Conditioned specimens

Experimental work

Preparation of field test specimens Cylindrical field cores obtained from MnROADTop and bottom discardedTop and bottom discardedIDT, SCB, and DCT test samples were cutAir void content determined in different study

Field cores air void contentCell Mean CV20 6.0 0%21 5.1 2%22 5.7 2%33 5.3 1%33 5.3 %34 5.9 2%35 6.4 2%77 5.1 13%

Sample preparation scheme for field cores

77 5.1 13%Air void content for

field cores

Experimental work – Test methods

DCTSamples conditioned in controlled chamber (min. 2 hours)Test performed under tensile loadingTest performed under tensile loadingUsed pre-load of 0.2 kNLoading rate: CMOD rate of 1mm/min (0.017 mm/s)Test completed when post-peak level reduced to 0 1 kNTest completed when post peak level reduced to 0.1 kNFracture energy computed from Load-CMOD plots

DCT test scheme


Typical DCT Load-CMOD curves (UIUC)

Experimental work – Test methodsSCBSCB

Samples conditioned in controlled chamber (2h)Contact load of max 0.3 kN

C O f / (Loading rate: CMOD rate of 0.0005 mm/s (34 times smaller than DCT)

Test completed when post-peak level reduced to 0.5 kNFracture toughness computed from peak loadFracture energy computed from Load-LLD plots

SCB test scheme


Typical SCB Load-LLD curves (UMN)


IDTDetermination of Creep StiffnessDetermination of Tensile StrengthDetermination of Tensile StrengthTest protocol AASHTO T 322-03

Analysis of Experimental Data

Analysis layout

Presentation of resultsPresentation of resultsStatistical analysis of data

Analysis of variance (ANOVA)Null Hypothesis: The effects of all the treatment groupsNull Hypothesis: The effects of all the treatment groups

are all null Alternate Hypothesis: The effect of at least one treatment

i t llgroup is not nullMultiple comparisonLevel of error for testing significance: 0.05

Note:The ‘NY’ mixture was not included in the statistical analysis, since

f f finformation was not available for all factor level combinations.

Effect of Mixture Type, Air Void Content, and Temperature on Fracture Parameters

Data analysis for unconditioned laboratory compacted specimens

Analysis of Experimental DataDCT F tDCT - Fracture energy

Results range 190 J/m2 to 800 J/m2

1400

1000

1200

1400

4% air - void content 7% air - void content

600

800

Gf[

J/m

2 ]

200

400

G

0

Test Temperature = PGLT+10 Test Temperature = PGLT

Analysis of Experimental DataSCB F tSCB - Fracture energy

Results range 300 J/m2 to 1380 J/m21400

1000

1200

1400


600

800

J/m

2 ]

200

400Gf[

J

0


Analysis of Experimental DataSCB F t t hSCB - Fracture toughness

Results range 0.45 MPa·m0.5 to 1.20 MPa·m0.51.40

1.00

1.20

0.5 ]


0.60

0.80

[Mpa

· m0

0.20

0.40KIC

0.00


Analysis of Experimental DataIDT T il t thIDT - Tensile strength

Results range 2.30 MPa to 7 MPa8.00

6.00

7.00

]


4.00

5.00

gth

[MPa

]

1.00

2.00

3.00

Stre

ng

0.00



Summary of ANOVA tables

Experimental i bl

DCT SCB SCB IDTFracture Fracture Fracture S hvariables Fracture Energy

Fracture Energy

Fracture Toughness Strength

Mix type √ √ √ √Void content − √ √ √Temperature √ √ − √

√ √Mix×Temp √ √ − −

√ Effect significant at 0 05 le el of error√ : Effect significant at 0.05 level of error− : Effect non-significant at 0.05 level of error


Statistical grouping & ranking of asphalt mixtures

DCT G SCB G SCBIDT

Mixture Type

DCT Gf

[J/m2]SCB Gf

[J/m2]SCB

KIC [MPa·m0.5 ]Strength[MPa ]

Group Rank Group Rank Group Rank Group RankMean Rank Mean Rank Mean Rank Mean Rank

20 423.4 C 741.6 A 0.858 A/B 4.7 A/B/C21 472.8 B /C 716.6 A 0.787 B 4.7 A/B/C22 426.1 C 563.1 B/C 0.853 A/B 4.9 A/B33 489.8 B/C 649.1 A/B 0.804 B 4.01 E34 583.6 A 821.6 A 0.890 A 4.6 B/C/D35 560 9 A/B 834 0 A 0 955 A 5 1 A35 560.9 A/B 834.0 A 0.955 A 5.1 A77 497.7 B/C 772.3 A 0.806 B 4.2 D/E

Wisconsin 298.6 D 457.3 C 0.831 B 4.4 C/D/E

Effect of mixture conditioning

Data analysis for conditioned laboratory compacted specimens

Analysis of Experimental DataDCT Fracture energy SCB Fracture energy

400

600

800

J/m

2 ]

gy

400

600

800

J/m

2 ]

SCB Fracture energy

0

200

400

Gf[

J

0

200

400

Gf[

J

8.00IDT Tensile Strength

1.50SCB Fracture Toughness

4.00

6.00

engt

h [M

Pa]

0 50

1.00

[MPa

·m0.

5 ]

0.00

2.00

Stre

0.00

0.50K

IC

Non-Conditioned Conditioned


35Creep Stiffness @ 60sec

Creep Stiffness at 60ses Creep Stiffness at 500sec

20

25

30

GPa

]

Creep Stiffness at 60ses Creep Stiffness at 500sec

5

10

15

S [G

0

Non-Conditioned Conditioned

Analysis of Experimental DataS f ANOVA t blSummary of ANOVA tables

Experimental i bl

DCT SCB SCB IDT

F t F t F tvariables Fracture energy

Fracture energy

Fracture toughness

Strength

Mix √ √ − √√ √Conditioning √ − √ −

Mix.Conditioning − − − −

Experimental variables IDT Creep stiffnessS60 S500

Mix √ √Mix √ √Conditioning √ −

Mix.Conditioning − −

√ : Effect significant at 0.05 level of error− : Effect non-significant at 0.05 level of error

Data analysis for field specimens


DCT - Fracture energy SCB - Fracture energy

1000 1000

600

800

m2 ] 600

800

1000

200

400Gf [

J/m

200

400

600

Gf[

J/m

2 ]

0Cell 77 Cell 34 Cell 33 Cell 21 Cell 35 Cell 20 Cell 22

0

200

Cell 35 Cell 22 Cell 77 Cell 34 Cell 33 Cell 20 Cell 21

Field 7% Lab Compacted 7% - Lab Compacted & Conditioned 4% Lab Compacted

Comparison field vs. laboratory compacted specimens (Test temperature PGLT)p y p p ( p )


SCB - Fracture toughness IDT - Tensile strength6.001.40

4.00

5.00

MPa

]

0 80

1.00

1.20

a·m

0.5 ]

2.00

3.00

Stre

ngth

[M

0.40

0.60

0.80

KIC

[MPa

0.00

1.00

Cell 77 Cell 35 Cell 21 Cell 20 Cell 34 Cell 33 Cell 220.00

0.20



Comparison field vs. laboratory compacted specimens (Test temperature PGLT)p y p p ( p )


Experimental variables

DCT SCB SCB IDTFracture Fracture Fracture

√ : Effect significant at 0.05 level of error

variablesenergy energy toughness Strength

Mix − − √ −

√ ec s g ca a 0 05 e e o e o− : Effect non-significant at 0.05 level of error

SCB fracture energy [J/m2 ]

Statistical grouping &

Mix Type Group Mean Rank

21 162.41 C20 207 16 B/Cranking of asphalt

mixtures20 207.16 B/C33 246.34 B/C34 288.36 A/B77 301 46 A/B77 301.46 A/B22 306.49 A/B35 421.29 A

Correlation field to laboratory compacted samples

Analysis of Experimental DataDCT - Fracture energy SCB - Fracture energy

1000

m2 ]

1000

m2 ]

600

800

om fi

eld

core

[J/m

600

800

m fi

eld

core

[J/m

400

ctur

e en

ergy

fro

400

ture

ene

rgy

from

0

200

0 200 400 600 800 1000

DC

T fr

ac

0

200

SCB

frac

0 200 400 600 800 1000

DCT fracture energy from laboratory samples [J/m2]

Identity line 4% Lab Compacted

0 200 400 600 800 1000SCB fracture energy from laboratory samples [J/m2]

7% Lab Compacted 7% Lab Compacted & Conditioned


5.50

6.00

a]1.10

1.20

MPa

·m0.

5 ]

SCB - Fracture toughness IDT - Tensile strength

5.00

5.50

field

cor

es [

MPa

1.00

1.10

m fi

eld

core

s [M

4.00

4.50

T st

reng

th fr

om f

0.80

0.90

re t

ough

ness

fro

3.00

3.50

3 00 3 50 4 00 4 50 5 00 5 50 6 00ID

T0.60

0.70

0 60 0 70 0 80 0 90 1 00 1 10 1 20

SCB

fra

ctur

3.00 3.50 4.00 4.50 5.00 5.50 6.00

IDT strength from laboratory specimens [MPa]

0.60 0.70 0.80 0.90 1.00 1.10 1.20

SCB fracture toughness from laboratory specimens [MPa/m0.5]

Identity line 4% Lab Compacted7% Lab Compacted 7% Lab Compacted & Conditioned

Analysis of Experimental DataC l ti ffi i tCorrelation coefficient

SCB SCB DCTTest conditions for laboratory samples

SCB Fracture energy

SCB Fracture

toughness

DCT Fracture energy

IDT Strength

7% PGLT 0 48 0 05 0 64 0 027%- PGLT -0.48 0.05 0.64 0.02

7%- PGLT-Conditioned 0.38 -0.25 0.26 -0.44

4% PGLT 0 20 0 25 0 81 0 414%- PGLT -0.20 -0.25 0.81 -0.41

Comparison of experimental results obtained at UIUC and UMN

Analysis of Experimental DataDCT test at UMN – mixture 22-7-34DCT DCT test at UMN – mixture 22-7-34DCT

700Comparison of DCT test performed at UMN and UIUC

500

600

[J/m

2 ]

DCT test at UIUC – mixture 22-7-34300

400

actu

re e

nerg

y

DCT test at UIUC mixture 22 7 34

100

200

DC

T fr

a

021-4-18 21-4-28 20-7-18 20-7-28 22-7-24 22-7-34

DCT performed at UIUC DCT performed at UMN


SCB test performed at UMN and UIUC SCB test performed at UMN and UIUC

SCB

1000

1200

1400

rgy

[J/m

2 ]

0.80

1.00

1.20

ss [

MPa

·m0.

5 ]

400

600

800

B fr

actu

re en

er

0.40

0.60

ctur

e tou

ghne

s

0

200

35-4-24 35-7-24 NY-7-12

SCB

0.00

0.20

35-4-24 35-7-24 NY-7-12 SC

B fr

ac

SCB performed at UIUC (Piston head)SCB performed at UMN (Piston head)SCB performed at UMN (LLD)

SCB performed at UIUC (Piston head)SCB performed at UMN (Piston head)SCB performed at UMN (LLD)

Analysis of Experimental DataSCB

SCB test at UIUCSCB test at UMN SCB test at UIUC mixture 35-4-24

SCB test at UMNmixture 35-4-24

Eff t f Mi t T Ai V id C t t d T tEffect of Mixture Type, Air Void Content and Temperature on the IDT creep stiffness

Data analysis for laboratory compacted specimens

Analysis of Experimental DataIDT - Creep stiffness @ 60 secIDT Creep stiffness @ 60 sec

20253035

s [G

Pa] 4% air - void content 7% air - void content

05

101520

S tif

fnes

s

IDT - Creep stiffness @ 500 sec

0

p @

20253035

[GPa

] 4% air - void content 7% air - void content

05

1015

Stiff

ness

[

0



Experimental variables IDT Creep StiffnessExperimental variablesS60 S500

Mix √ √Void √ √Void √ √

Temperature √ √Mix·Void √ √

√Mix·Temp − √Void·Temp √ √

Mix·Void·Temp √ √Vo d e p √ √




IDT creep stiffness [MPa ]p [ ]Mix Type

S60 Mean Rank S500

Mean Rank

20 12.33 B/C 15.878 B21 12.039 C 16.222 B22 17.81 A 19.043 A/B33 12.388 B/C 16.354 B34 12 69 B/C 16 219 B34 12.69 B/C 16.219 B35 13.954 B/C 17.418 A/B77 14.207 B 16.599 B

Wisconsin 18 481 A 21 028 AWisconsin 18.481 A 21.028 A

IDT creep stiffness

D t l i f fi ld iData analysis for field specimens

Analysis of Experimental DataIDT Creep stiffness @ 60 secIDT - Creep stiffness @ 60 sec

25

30

35

[GPa

]

5

10

15

20C

reep

Stif

fnes

s

IDT - Creep stiffness @ 500 sec

0

5


C

30

20

25

30

ss [G

Pa]

5

10

15

Cre

ep S

tiffn

es

0Cell 22 Cell 34 Cell 33 Cell 21 Cell 77 Cell 20 Cell 35

C


Analysis of Experimental DataIDT C tiff l ti fi ld t l b t iIDT Creep stiffness correlation field to laboratory specimens

30

35

GPa

] 30

35

[GPa

]

15

20

25

m fi

eld

core

s [G

15

20

25

m fi

eld

core

s

0

5

10

S60

from

0

5

10

S500

from

Identity line 4% Lab Compacted7% Lab Compacted 7% Lab Compacted & Conditioned

0 5 10 15 20 25 30 35

S60 from LabCompacted [GPa]

0 5 10 15 20 25 30 35

S500 from Lab-compacted [GPa]

7% Lab Compacted 7% Lab Compacted & Conditioned

Correlation coefficients of Field data to LabTest conditions S60 S500

7% PGLT 0 26 0 737%- PGLT 0.26 0.737%- PGLT-Conditioned 0.61 0.61

4%- PGLT 0.36 0.47

Effect of asphalt modificationon laboratory compacted specimens

Analysis of Experimental DataDCT Fracture Energy SCB Fracture Energy

1050

1400

m2 ]

DCT Fracture Energy

1050

1400

m2 ]

SCB Fracture Energy

350

700

Gf[

J/m

350

700

Gf[

J/m

0 0

6 00

IDT Tensile Strength

4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

SCB Fracture Toughness

4.00

6.00

engt

h [M

Pa]

1.00

1.50

[MPa

·m0.

5 ]

0.00

2.00Stre

4% 7% 4% 7%4% 7% 4% 7% 0.00

0.50KIC

[

PPA Elvaloy+PPA SBS SBS+PPA

4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT



DCT SCB SCB IDTExperimental

variables

DCT SCB SCB IDT

Fracture energy

Fracture energy

Fracture toughness Strengthgy gy g g

Void − √ √ √

Temperature √ √ − √√ √ √ √Modifier √ √ √ √




Modifier

DCT Gf[J/m2]

SCB Gf[J/m2]

SCB KIC[MPa/m0.5 ]

IDT strength [MPa ]

Group Rank Group Rank Group Rank Group RankMean Rank Mean Rank Mean Rank Mean Rank

SBS 560.9 A/B 834 A 0.96 A 5.1 ASBS+PPA 583.6 A 822 A/B 0.89 A/B 4.6 B

Elavaloy+PPA 495.7 B 772 A/B 0.81 B 4.2 CPPA 489.8 B 649 B 0.80 B 4.0 C

Analysis of Experimental DataIDT Creep Stiffness S@60 IDT Creep Stiffness S@500

20

30

a]

IDT Creep Stiffness S@60

20

30

a]

IDT Creep Stiffness S@500

10S [G

Pa

10S [G

Pa


4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

0 0 4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT


IDT Creep stiffnessS60 S500


variables S60 S500Void √ √

Temperature √ √Modifier − −Modifier


Effect of asphalt modificationon field specimens

Analysis of Experimental DataDCT Fracture Energy Field Cores SCB Fracture Energy Field Cores

700

1050

1400

J/m

2 ]

DCT Fracture Energy- Field Cores

700

1050

1400

m2 ]

SCB Fracture Energy- Field Cores

FieldPGLT

7%PGLT

7%PGLT

7%PGLT+10

0

350

700

Gf[

J

0

350

700

Gf[

J/m

Field 7% 7% 7%PGLT PGLT PGLT -

ConditionedPGLT+10 PGLT PGLT PGLT -

ConditionedPGLT+10

6.00

a]

IDT Tensile Strength - Field Cores1.50

5 ]

SCB Fracture Toughness - Field Cores

2.00

4.00

reng

th [M

Pa

0.50

1.00

IC[M

Pa·m

0.5

0.00

Str

FieldPGLT

7%PGLT

7%PGLT -

Conditioned

7%PGLT+10

FieldPGLT

7%PGLT

7%PGLT -

Conditioned

7%PGLT+10

0.00

KI



Experimental DCT SCB SCB IDT

pvariables Fracture

energyFracture energy

Fracture toughness Strength

Modifier − √√ − −Modifier √√√ : Effect significant at 0.05 level of error− : Effect non-significant at 0.05 level of error


SCB fracture energy [J/m2 ]GModifier Group Mean Rank

SBS 421.9 AElvaloy+PPA 301 6 A/BElvaloy+PPA 301.6 A/B

SBS+PPA 288.6 A/BPPA 246.3 B

Analysis of Experimental DataIDT Creep Stiffness at 60sec - Field IDT Creep Stiffness at 500sec - Field

20

30

Pa]

IDT Creep Stiffness at 60sec - Field

20

30

Pa]

IDT Creep Stiffness at 500sec - Field

0

10S [G

P

0

10S [G

P


FieldPGLT

7%PGLT

7%PGLT -

Conditioned

7%PGLT+10

0 0FieldPGLT

7%PGLT

7%PGLT -

Conditioned

7%PGLT+10

Experimental IDT Creep stiffness




Modifier − −


Effect of RAP fractioningon laboratory compacted specimens


700

1050

1400

J/m

2 ]

DCT Fracture Energy

700

1050

1400

J/m

2 ]

SCB Fracture Energy

4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

0

350

700

Gf[

J

0

350

700

Gf[

J

4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLTPGLT+10 PGLT+10 PGLT PGLT PGLT+10 PGLT+10 PGLT PGLT

6.00

MPa

]

IDT Tensile Strength1.50

m0.

5 ]

SCB Fracture Toughness

2.00

4.00

Stre

ngth

[M

0.50

1.00

KIC

[MPa

·m0.00

4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

0.00

K

Non-fractioned Fractioned




variables Fracture energy

Fracture energy

Fracture toughness Strength

Void −− −− √√ √√

Temperature √√ −− −− √√

F ti i √√Fractioning −− −− √√ −−


Analysis of Experimental DataIDT Creep Stiffness S@60 IDT Creep Stiffness S@500

20

30

Gpa

]

p @

20

30

Gpa

]

C eep S ess S@500

4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

0

10S [G

0

10S [G

PGLT+10 PGLT+10 PGLT PGLT PGLT+10 PGLT+10 PGLT PGLT


Summary of ANOVA tablesExperimental

variablesIDT Creep stiffnessS60 S500

V id √√


Void −− √√Temperature √√ √√Fractioning −− −−


Effect of RAP fractioningon field specimens

Analysis of Experimental DataDCT Fracture Energy Field Cores SCB Fracture Energy Field Cores

700

1050

1400

J/m

2 ]

DCT Fracture Energy- Field Cores

700

1050

1400

J/m

2 ]

SCB Fracture Energy - Field Cores

FieldPGLT

7%PGLT

7%PGLT

7%PGLT+10

0

350

700

Gf[

J

0

350

700

Gf [J

FieldPGLT

7%PGLT

7%PGLT

7%PGLT+10PGLT PGLT PGLT

ConditionedPGLT+10 PGLT PGLT PGLT

ConditionedPGLT+10

6.00

MPa

]

IDT Tensile Strength - Field Cores1.50

5 ]

SCB Fracture Toughness - Field Cores

2.00

4.00

Stre

ngth

[M

0.50

1.00

KIC

[MPa

·m0.

5

0.00FieldPGLT

7%PGLT

7%PGLT

Conditioned

7%PGLT+10

FieldPGLT

7%PGLT

7%PGLT

Conditioned

7%PGLT+10

0.00

K





DCT SCB SCB IDT

Fracture energy

Fracture energy

Fracture toughness Strengthenergy energy toughness

Fractioning −− −− −− −−


Analysis of Experimental DataIDT Creep Stiffness at 60sec - Field 30 IDT Creep Stiffness at 500sec - Field

20

30

ess [

GPa

]

p

20

30

ness

[GPa

]

p

FieldPGLT

7%PGLT

7%PGLT

Conditioned

7%PGLT+10

0

10

Stiff

ne

0

10

Stiff

n

FieldPGLT

7%PGLT

7%PGLT

Conditioned

7%PGLT+10

Conditioned

Non-fractioned FractionedConditioned



IDT Creep stiffness

S60 S500


variables S60 S500

Fractioning −− −−


Effect of binder PG low limiton laboratory compacted specimens


1050

1400

m2 ]

DCT Fracture Energy

1050

1400

m2 ]

SCB Fracture Energy

350

700

Gf[

J/m

350

700

Gf[

J/m

4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

0 0

6 00IDT Tensile Strength

4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

1.50SCB Fracture Toughness

4.00

6.00

th [M

Pa]

1.00

MPa

·m0.

5 ]

0.00

2.00

Stre

ngt

4% % 4% %4% % 4% % 0 00

0.50

KIC

[M

0.00 4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

PG 58-28 PG 58-34

0.00

Analysis of Experimental DataSummary of ANOVA tables


variables

DCT SCB SCB IDT

Fracture energy

Fracture energy

Fracture toughness Strengthenergy energy toughness Strength

Void √√ −− √√ √√

Temperature √√ √√ −− √√

PG −− √√ −− −−


Analysis of Experimental DataIDT Creep Stiffness at 60 sec IDT Creep Stiffness at 500 sec

30

40

pa]

IDT Creep Stiffness at 60 sec

30

40

pa]

IDT Creep Stiffness at 500 sec

10

20

S [G

p

10

20

S [G

p


0 4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

0 4%PGLT+10

7%PGLT+10

4%PGLT

7%PGLT

PG 58-28 PG 58-34Summary of ANOVA tables



Void − −Temperature √ √

PGLT − √PGLT − √√ : Effect significant at 0.05 level of error− : Effect non-significant at 0.05 level of error

Effect of binder PG low limiton field specimens

Analysis of Experimental DataDCT Fracture Energy- Field Cores SCB Fracture Energy - Field Cores

1050

1400

m2 ]

DCT Fracture Energy Field Cores

1050

1400

m2 ]

SCB Fracture Energy Field Cores

350

700

Gf[

J/m

350

700

Gf[

J/m

FieldPGLT

7%PGLT

7%PGLT

Conditioned

7%PGLT+10

0 0

6.00IDT Tensile Strength - Field Cores

FieldPGLT

7%PGLT

7%PGLT

Conditioned

7%PGLT+10

1 50SCB Fracture Toughness - Field Cores

4.00

th [M

Pa]

1.00

1.50

Pa·m

0.5 ]

0.00

2.00

Stre

ngt

0 00

0.50

KIC

[MP

0.00FieldPGLT

7%PGLT

7%PGLT

Conditioned

7%PGLT+10

FieldPGLT

7%PGLT

7%PGLT

Conditioned

7%PGLT+10

PG 58-28 PG 58-34

0.00




DCT SCB SCB IDT

Fracture Fracture Fracture Strengthenergy energy toughness Strength

PG −− √√ −− −−

√ : Effect significant at 0.05 level of errorEff t i ifi t t 0 05 l l f− : Effect non-significant at 0.05 level of error

Analysis of Experimental DataIDT Creep Stiffness at 60sec - Field IDT Creep Stiffness at 500sec - Field

20

30

[GPa

]

IDT Creep Stiffness at 60sec Field

20

30

[GPa

]

p

10

Stiff

ness

10

Stiff

ness

PG 58-28 PG 58-34

0 0FieldPGLT

7%PGLT

7%PGLT

Conditioned

7%PGLT+10

FieldPGLT

7%PGLT

7%PGLT

Conditioned

7%PGLT+10


Experimental IDT Creep stiffnesspvariables

C eep st essS60 S500

PG −− √√


Conclusions & Summary of FindingsUnconditioned laboratory compacted mixtures

DCT fracture energy from approximately 190 J/m2 to 800 J/m2. gy yValues at PGLT+10˚C always larger than those at PGLT, except for mixture ‘Wisconsin’. Overall, effect of the air void content on DCT fracture energy appeared to be minimal.gy pp

SCB fracture energy between 300 and 1380 J/m2. Values at PGLT+10˚C always higher than those at PGLT. SCB fracture G 0 C a ays g e a ose a G SC ac u eenergy decreases when air void content increases.

SCB fracture toughness from 0.45 to 1.20 MPa•m0.5. For 4% airSCB fracture toughness from 0.45 to 1.20 MPa m . For 4% air voids, SCB fracture toughness increased with temperature decrease. Contrarily to SCB fracture energy, KIC results suggest temperature has a minimal effecttemperature has a minimal effect.

Conclusions & Summary of Findings

IDT tensile strength ranged from 2.30 to 7 MPa. Strength was higher for mixtures with lower air void content. In addition, except gfor a few mixtures, the strength values obtained at PGLT+10˚C were higher than the values obtained at PGLT. NY mixture had significantly higher IDT strength at 7% air voids. This mixture g y g gcould not be compacted to 4% air voids.

Multiple comparisons, at 5% level of significance, performed to u t p e co pa so s, a 5% e e o s g ca ce, pe o ed ocompare and rank laboratory mixtures, according to different test methods. Mixture in cell 35 scored the best and ranked in first category for all test methods. The mixture fromfirst category for all test methods. The mixture from Wisconsin ranked the least favorable out of all mixtures tested (NY mixture not included in the analysis since it could not be compacted to 4%)compacted to 4%).

Conclusions & Summary of FindingsField Cores

Except for SCB fracture energy, the mixtures are statistically gy ysimilar. For SCB fracture energy, the best performer was again the mixture from cell 35.

Comparison between laboratory mixtures and field cores was performed by means of data correlation and correlation plots. The best match was observed for DCT fracture energy. For SCB bes a c as obse ed o C ac u e e e gy o SCfracture energy, significantly lower values were obtained for field cores compared to laboratory samples.


Factor Effects

Mi diti i f d i ifi t l f DCT f tMix conditioning was found significant only for DCT fracture energy and SCB fracture toughness. DCT fracture energy decreased with mix conditioning, and SCB fracture toughness i d i h i di i iincreased with mix conditioning.

Asphalt modification had a significant effect on fracture properties of laboratory mixtures. A multiple comparison indicates that the SBS modified mixture (cell 35) ranked the best overall.

For the field cores, however, asphalt modification was significant only for SCB fracture energy. The statistically significant higher fracture energy was again observed for cell 35 g g gy gmixture


Factor Effects

Th ff t f RAP f ti i i l b t t d h ltThe effect of RAP fractioning in laboratory compacted asphalt mixtures was found statistically not significant except for the SCB fracture toughness. For the field cores, RAP fractioning was found i i ifi f ll linsignificant for all test results.

The effect of PG lower limit was found statistically significant only for SCB fracture energy. For the laboratory mixtures, the PG 58-28 mixture tested at PGLT had higher fracture energy compared to the PG 58-34 mixture. The opposite was true for the field cores.


The limited comparison of the results obtained at UMN pand UIUC laboratories, respectively, indicated significant differences for both DCT and SCB test results

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