Mihai Marasteanu – University of MinnesotaNCAUPG Annual Meeting, January 2007

LowLow--Temperature Cracking in Temperature Cracking in Asphalt PavementsAsphalt Pavements

LowLow--Temperature CrackingTemperature Cracking

Good fracture resistance essential for asphalt pavements in northern US and in Canada

Low-temperature cracking represents the prevalent distress in Minnesota and neighboring states

Low Temperature Cracking Pooled Fund Low Temperature Cracking Pooled Fund State ParticipationState Participation

ConnecticutIdahoIowa

IllinoisKansas

MinnesotaNorth Dakota

New YorkVermontWisconsinWashington

and FHWA

http://www.pooledfund.org

Research team - four universitiesUMN, UIUC, WISC, ISU

Low Temperature Cracking Pooled Fund (Overall Plan)

State FieldSamples

(Good / Poor Performance)

Laboratory PreparedSamples

Laboratory Testing and Data Analysis

Verify Models

Field Validation of Results(Test Sections)

Phase 1

Phase 2

Pooled Fund Study Goals

• Development of test methods / protocols for LTC• What is the best test for binders and mixtures?

• Validate / refine MEPDG thermal cracking model

• Establish guidelines for MnROAD field validation

Field Samples

State Road AsphaltBinder

Performance(1=Good)(5=Bad)

Age(Years) Pavement Comment Recommendation

IL US-20 AC-10, AC-20 2 20 Accepted

IL I-74 AC-20 2 15 original surface will soon be milled and replaced Accepted

MN Cell 33 PG 58-28 3 6 silty clay subgrade constructed in 1994 Accepted

MN Cell 34 PG 58-34 1 6 silty clay subgrade constructed in 1994 Accepted

MN Cell 35 PG 58-40 4 6 silty clay subgrade constructed in 1994 Accepted

MN Cell 3 PG 58-28120/150 3 14 silty clay subgrade constructed in

1992 Accepted

MN Cell 19 PG 64-22AC-20 4 14 silty clay subgrade constructed in

1992 Accepted

MN CSAH-75section 4WB PG 58-34 3 10 sand-gravel subgrade

constructed in 1955 Accepted

MN CSAH-75section 2EB PG 58-28 4 10 sand-gravel subgrade

constructed in 1955 Accepted

ND SH-18 120/150 4 8 A thin lift overlay has been placed over part of this project

Not recommended: overlay placed on original pavement

WI US-45 PG 58-34, 58-4085/100, 120/150 2 10 only difference in NB and SB

lanes was binder Accepted

WI STH-73 PG 58-28 1 5 subbase stabilized with asphaltic base course Accepted

LVR - Cell 33 Eastbound

25' core area 25' core area500'wheel path

Cores 1-18Beams 1-6

Cores 19-27Beams 7-9

wheel pathwheel path

wheel path

102 kip

80 kip

sta 63+75(up close to edge)

6" core 6" core

24" center to center

6" core 6" core

6" core 6" core

18" slight spacing if necessary

sta 68+75(up close to edge)

(3) 6" x 18" x depth beams

18

15 16119 10

13 17 18

3 4 57 12

14

62 1

63

452 22

25

20192326

212427

7

98

Field Samples

MnROAD Sample Extraction

IL US20 Slab Extraction

Field Samples InformationBeams - received Spring 2005

L l h1 MnRoad 03 05 BB 008 470 176 1602 MnRoad 33 05 BB 006 405 195 1153 MnRoad 33 05 BB 005 405 195 1134 MnRoad 19 05 BB 07 480 212 2055 MnRoad 19 05 BB 08 480 203 2006 MnRoad 35 05 BB 08 470 155 1027 MnRoad 34 05 BB 01 445 168 1118 MnRoad 35 05 BB 09 470 192 1079 MnRoad 34 05 BB 06 470 183 112

Cell Year Mix Spot Dimensions

Field Samples Information

Cell 33

L=105D=150

1 MnRoad 33 05 BC 32 MnRoad 33 05 BC 73 MnRoad 33 05 BC 104 MnRoad 33 05 BC 165 MnRoad 33 05 BC 236 MnRoad 33 05 BC 247 MnRoad 33 05 BC 258 MnRoad 33 05 BC 269 MnRoad 33 05 BC 27

10 MnRoad 33 05 BC 0911 MnRoad 33 05 BC 1512 MnRoad 33 05 BC 1113 MnRoad 33 05 BC 0514 MnRoad 33 05 BC 0815 MnRoad 33 05 BC 1316 MnRoad 33 05 BC 1217 MnRoad 33 05 BC 1418 MnRoad 33 05 BC 04

Received

Nov-05Nov-05

SpotCell Year Mix

Nov-05Nov-05Nov-05Nov-05Nov-05Nov-05Nov-05

spring 2005spring 2005spring 2005spring 2005spring 2005spring 2005spring 2005spring 2005spring 2005

Laboratory ExperimentLaboratory Experiment

××PG64-22Plain 1

××PG64-28SBS 2

××PG64-28plain 1

××PG64-34Black Max

××PG64-34Elvaloy

××PG58-28plain 2

××××××××PG58-28plain 1

××PG58-34SBS 1

×××PG58-34Elvaloy

×××PG58-40SBS 1

Binder Type

+0.5%Design+0.5%Design+0.5%Design+0.5%DesignBinder Content

LimestoneGraniteLimestoneGraniteAggregate Type

As constructed (7%)Design (4%)Air Voids

Laboratory Prepared Specimens

XMixture and BinderDilatometric Measurements

XBinder Fracture TestSENB

XXBinder Low Temperature BBR and DTT

X*XMixture Thermal Stress TestTSRST

XMixture Fracture TestSCB

XMixture Fracture TestSE(B)

XMixture Fracture TestDisc Compact Tension

XMixture Indirect TensionCreep and Strength

WISCUMNUIUCMTU

Mixture and Binder Test TemperaturesMixture and Binder Test Temperatures

Test at 3 temperaturesMatch 2 out of 3 temperatures for binders

and mixtures–For mixtures 6°C do not lead to big change in properties

Binders:PG +10°C (for a -28 it will be -18°C), 6°C below

it (-24°C) and 12°C below it (-30°C)Mixtures:

PG +10°C, 12°C below it, 12°C above it.

Fracture Testing Fracture Testing -- UIUCUIUCDisc Shaped Compact Tension

DC(T)1 mm/min CMOD150mm

Single Edge Notched Beam

SE(B)1 mm/min CMOD50x75x375mm

Fracture Energy Fracture Energy –– GGff (J/m(J/m22))

Gf

CMOD

Load

Softening

Peak Load

Time to Peak Load

SCBSCB

Fracture EnergyFracture Energy

P

OO'

A W

Wtail

uuc

lig

ff A

WG =

Wf: work of fractureAlig: area of the ligament

∫= PduW f

α

δ

P 0

r

2 s

c lip g ua ge

lo a d in gro lle r

sup p o rtro lle r

a

Stress Intensity Factor KStress Intensity Factor KII

ΙΙ = YaK πσ0

Brs

rsYa

KI

I 0

00)/(

∆+=

πσ

))r/a(Cexp(C)r/a(CCY 4321)r/s(I 0 ++=

165.65.2 )ra(0839.215)

ra(97042.27)

ra(64035.1655676.6B +++=

SCB Test PlotsSCB Test Plots

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

-0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7LLD (mm)

Load

(kN)

B2-1-22-12

B2-2-22-12

B2-3-22-12

B2-1-21-24

B2-2-21-24

B2-3-21-24

B2-1-31-36

B2-2-31-36

B2-3-31-36

SCB SCB -- temperature effect on Ktemperature effect on KICIC and and GGff

0.00

0.30

0.60

0.90

1.20

1.50

-40 -30 -20 -10 0

Temp(°C)

KI(M

Pa.m

0.5)

0

200

400

600

800

1000

1200

1400

Frac

ture

Ene

rgy(

N/m

)

B1-KI

B2-KI

F1-KIB1-Energy

B2-Energy

F1-Energy

IDT IDT –– Creep and StrengthCreep and Strength

Specification type testsIn addition:

Limited creep tests at different load levelsLimited strength

tests at different loading rates

IDT Creep DataIDT Creep Data

TSRSTTSRST

Tensile Strength Restrained Stress Test

Lab prepared beamsField beams

Acoustic EmissionAcoustic Emission

Source Sensor

( xi , yi , zi )

( x0 , y0 , z0 )

( ) ioipi ttcd ε+−=

( ) ( ) ( )202

02

0 zzyyxxd iiii −+−+−=

Cp: Wave speed- from calibration

Ti: Event Arrive time- from recording

Acoustic EmissionAcoustic Emission

0

0.5

1

1.5

2

2.5

3

3.5

0 500 1000 1500 2000 2500

Time (sec)

Even

t Cou

nt

0

500

1000

1500

2000

2500

3000

3500

4000

Load

ing(

KN

)

LoadingAE count

0

0.5

1

1.5

2

2.5

3

3.5

0 500 1000 1500 2000 2500

Time (sec)

Load

-100

100

300

500

700

900

1100

1300

1500

AE

Ener

g

LoadAE Energy

Acoustic Emission Event LocationAcoustic Emission Event Location

05

1015202530354045505560657075

-75 -65 -55 -45 -35 -25 -15 -5 5 15 25 35 45 55 65 75

Notch05

1015202530354045505560657075

-75 -65 -55 -45 -35 -25 -15 -5 5 15 25 35 45 55 65 75

Notch

-75-70-65-60-55-50-45-40-35-30-25-20-15-10-505

1015202530354045505560657075

-75 -65 -55 -45 -35 -25 -15 -5 5 15 25 35 45 55 65 75

Binder TestingBinder Testing

Binders used to prepare laboratory mixturesBinders recovered from top layer of field samplesTest methods

BBR – 1000sDT – 3%/minDENT – 1.8%/minAll three after 1h and 20h conditioning

DENTDENT

DilatometricDilatometric Measurements Measurements

Precision Capillary Tube

Silicon Rubber O-ringStainless Steal FittingPolypropylene

Washer

Housing

Base Cup Binder SpecimenSilicon Paper

Fracture Energy at TFracture Energy at THH

Fracture Energy Ranking at TH Highest: 64-34:B:4:GR

Lowest: 64-22:P1:4:LMNot calculated: 58-40:M1

0

200

400

600

800

1000

1200

1400

1600

64-3

4:B:4:

GR64

-34:B

:4:LM

64-3

4:E:4:

GR

58-3

4:S1:4

:GR

58-3

4:E:4:

GR64

-34:E

:4:LM

58-3

4:E:4:

GR:+0.5

AC

58-2

8:P2:4

:GR

58-3

4:S1:4

:LM58

-34:E

:4:LM

64-2

8:S2:4

:GR

58-2

8:P1:4

:GR

64-2

8:P1:4

:GR

64-2

8:S2:4

:LM

58-2

8:P2:4

:LM

58-2

8:P1:4

:GR:+

0.5AC

64-2

2:P1:4

:GR

58-2

8:P1:7

:GR:+

0.5AC

58-2

8:P1:4

:LM:+

0.5AC

64-2

8:P1:4

:LM

58-2

8:P1:4

:LM

58-2

8:P1:7

:GR

58-2

8:P1:7

:LM

58-2

8:P1:7

:LM:+

0.5AC

64-2

2:P1:4

:LM

Mixture

Frac

ture

Ene

rgy(

J/m

2 )

Fracture Energy at TFracture Energy at TMM

Fracture Energy Ranking at TMHighest: 58-40:S1:4:GR:+0.5AC

Lowest: 58-28:P1:7:LM:+0.5AC

0

200

400

600

800

1000

1200

1400

1600

58-40

:S1:4

:GR:+0

.5AC

58-40

:S1:4

:GR

64-34

:B:4:

GR

58-40

:S1:4

:LM

64-34

:B:4:

LM

64-22

:P1:4

:GR

58-34

:S1:4

:GR

64-34

:E:4:

GR

64-28

:S2:4

:GR

58-34

:E:4:

GR:+0.5AC

58-28

:P1:4

:GR:+0

.5AC

58-34

:E:4:

GR

58-28

:P1:4

:GR

58-28

:P2:4

:GR

58-28

:P1:7

:GR:+0

.5AC

64-22

:P1:4

:LM

58-28

:P1:7

:GR

64-28

:S2:4

:LM

64-28

:P1:4

:GR

64-34

:E:4:

LM

58-28

:P1:4

:LM

58-28

:P1:4

:LM:+0.5

AC

58-34

:S1:4

:LM

58-28

:P1:7

:LM

58-28

:P2:4

:LM

58-34

:E:4:

LM

64-28

:P1:4

:LM

58-28

:P1:7

:LM:+0.5

AC

Mixture

Frac

ture

Ene

rgy(

J/m

2 )

Fracture Energy at TFracture Energy at TLL

Fracture Energy Ranking at TL

Highest: 58-40:S1:4:GR:+0.5AC

Lowest: 58-28:P1:7:LM

0

100

200

300

400

500

600

700

58-40

:S1:4:G

R:+0.5A

C

58-40

:S1:4:G

R

64-34

:B:4:GR

64-28

:S2:4:G

R

58-34

:E:4:GR:+0.5

AC

58-34

:S1:4:G

R

58-28

:P1:4:G

R

64-34

:E:4:GR

58-28

:P1:4:G

R:+0.5A

C

58-40

:S1:4:LM

58-34

:E:4:GR

58-28

:P1:7:G

R:+0.5A

C

58-28

:P2:4:G

R

64-22

:P1:4:G

R

64-28

:S2:4:LM

58-34

:S1:4:LM

58-28

:P2:4:LM

64-34

:B:4:LM

64-28

:P1:4:G

R

58-28

:P1:7:G

R

58-28

:P1:4:LM

:+0.5AC

64-22

:P1:4:LM

64-34

:E:4:LM

58-28

:P1:4:LM

58-34

:E:4:LM

58-28

:P1:7:LM

:+0.5AC

64-28

:P1:4:LM

58-28

:P1:7:LM

Mixture

Frac

ture

Ene

rgy(

J/m

2 )

Fracture Toughness at TFracture Toughness at THH

Fracture Toughness Ranking at THHighest: 58-34:E:4:GR

Lowest: 58-28:P1:7:LM

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

58-34

:E:4:

GR

64-34

:E:4:

GR

58-34

:E:4:

GR:+0.5AC

58-34

:S1:4

:LM

64-34

:B:4:

GR64

-34:E

:4:LM

58-34

:S1:4

:GR

64-28

:P1:4

:GR

64-28

:P1:4

:LM58

-34:E

:4:LM

64-28

:S2:4

:GR

58-28

:P2:4

:GR

58-28

:P1:4

:GR

64-34

:B:4:

LM

58-40

:S1:4

:GR

64-28

:S2:4

:LM

58-40

:S1:4

:GR:+0

.5AC

58-40

:S1:4

:LM

64-22

:P1:4

:GR

58-28

:P1:4

:LM:+0.5

AC

58-28

:P1:4

:LM

58-28

:P2:4

:LM

58-28

:P1:7

:GR

64-22

:P1:4

:LM

58-28

:P1:7

:GR:+0

.5AC

58-28

:P1:7

:LM:+0.5

AC

58-28

:P1:7

:LM

Mixture

Frac

ture

Tou

ghne

ss(M

Pa.m

0.5 )

Fracture Toughness at TFracture Toughness at TMM

Fracture Toughness Ranking at TM

Highest: 64-34:B:4:GR

Lowest: 58-28:P1:7:LM+0.5AC

0

0.2

0.4

0.6

0.8

1

1.2

64-34

:B:4:GR

64-34

:E:4:GR

58-34

:S1:4:G

R

58-34

:E:4:GR

64-34

:B:4:LM

64-28

:S2:4:G

R

58-34

:E:4:GR:+0

.5AC

58-40

:S1:4:G

R

58-34

:S1:4:LM

64-34

:E:4:LM

58-28

:P2:4:G

R

64-28

:P1:4:G

R

64-22

:P1:4:G

R

64-28

:S2:4:LM

58-28

:P1:4:G

R

58-28

:P2:4:LM

58-40

:S1:4:LM

58-40

:S1:4:G

R:+0.5A

C

58-28

:P1:4:G

R:+0.5A

C58

-34:E:4:

LM

58-28

:P1:7:G

R:+0.5A

C

64-22

:P1:4:LM

64-28

:P1:4:LM

58-28

:P1:7:G

R

58-28

:P1:4:LM

58-28

:P1:4:LM

:+0.5A

C

58-28

:P1:7:LM

58-28

:P1:7:LM

:+0.5A

C

Mixture

Frac

ture

Tou

ghne

ss(M

Pa.

m0.

5 )

Fracture Toughness at TFracture Toughness at TLL

Fracture Toughness Ranking at TLHighest: 64-34:B:4:GR

Lowest: 58-28:P1:7:LM

0

0.2

0.4

0.6

0.8

1

1.2

1.4

64-34

:B:4:GR

58-40

:S1:4:G

R

58-34

:S1:4:G

R

58-34

:E:4:GR:+0

.5AC

58-34

:E:4:GR

64-34

:E:4:GR

64-28

:S2:4:G

R

58-40

:S1:4:G

R:+0.5A

C64

-34:B:4:

LM

58-28

:P2:4:G

R

64-28

:P1:4:G

R

58-28

:P1:4:G

R:+0.5A

C

58-28

:P1:4:G

R

58-40

:S1:4:LM

58-34

:S1:4:LM

64-34

:E:4:LM

64-22

:P1:4:G

R

58-28

:P1:7:G

R

64-28

:S2:4:LM

58-28

:P2:4:LM

58-28

:P1:4:LM

58-28

:P1:4:LM

:+0.5A

C

64-28

:P1:4:LM

58-28

:P1:7:G

R:+0.5A

C58

-34:E:4:

LM

64-22

:P1:4:LM

58-28

:P1:7:LM

:+0.5A

C

58-28

:P1:7:LM

Mixture

Frac

ture

Tou

ghne

ss(M

Pa.m

0.5 )

ConclusionsConclusions

At low temperature, asphalt mixtures are complex viscoelastic composite materials that are significantly temperature and loading rate dependent

Testing temperatures should be established relative to expected low pavement temperature and relative to low temperature PG grade for location of interestThe effect of loading rate needs to be investigated to better match true field cooling rates

Mixture and binder test temperatures should be matched as much as possible to better understand the contribution of the binder to the fracture properties of mixtures

ConclusionsConclusionsAsphalt binder testing alone does not provide sufficient reliability to predict low temperature cracking of asphalt pavements

The effect of aggregate type appears to have a significant effect for mixtures made with the same asphalt binder

PG system provides a good starting point, however, further refinement of the current system.

Role of the BBR “m” value should be re-consideredPhysical hardening has a significant effect on measured binder properties

ConclusionsConclusionsThe current specifications for low temperature cracking for both asphalt binders and mixtures do not include a fracture test

Two simple mixture tests, the disk-shaped compact tension test and semi-circular bend test, were investigated and were successfully used The binder direct tension test protocol was modified to obtain binder characteristics needed for better ranking at low temperatureHowever, need an improved binder test, that gives the same type of information as the mixture test, i.e. provide post-peak behavior

ConclusionsConclusions

The current indirect tensile test provides useful information for the complete evaluation of low temperature behavior of asphalt mixtures, but is not the best choice for a simple screening test The current thermal stress restrained specimen test can become a useful research tool to analyze the stress development and fracture mechanism in asphalt mixtures at low temperatures if further refined

Thank you!Thank you!