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NCHRP-IDEA Projects 84 and 104 — Academia/Government/Industry Collaboration That Pays Off! PowerPoint PPT Presentation


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5% EVA (high MW). °. -30. C. -24. C. °. 5% EVA (low MW). 5% SBS radial. SBS triblock. diblock. 5% SB. (with 0.2% Sulfur). AAG (unmodified). 60. 0. 20. 40. 80. Fracture Energy (J/m 2 ). NCHRP-IDEA Projects 84 and 104 — Academia/Government/Industry Collaboration That Pays Off!

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NCHRP-IDEA Projects 84 and 104 — Academia/Government/Industry Collaboration That Pays Off!

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Nchrp idea projects 84 and 104 academia government industry collaboration that pays off

5% EVA (high MW)

°

-30

C

-24

C

°

5% EVA (low MW)

5% SBS radial

SBS triblock

diblock

5% SB

(with 0.2% Sulfur)

AAG (unmodified)

60

0

20

40

80

Fracture Energy (J/m2)

NCHRP-IDEA Projects 84 and 104 — Academia/Government/Industry Collaboration That Pays Off!

Improved Asphalt Binder Specification Grading

Principal Investigator Simon A.M. Hesp, Queen’s University, Kingston, Ontario

Co-Principal Investigator Kai K. Tam, Ministry of Transportation of Ontario, Downsview, Ontario

Concept and Innovation

Ontario and Alberta Pavement Trials

Main Research Findings

Large Variations for Same AASHTO M320 Grade

A large number of studies have established that the asphalt grading system developed under the Strategic Highway Research Program should be improved. An extended bending beam rheometer (BBR) test protocol provides grades that will more effectively eliminate transverse cracking in service compared to the original BBR method. Simple compact tension tests can measure fracture energy (Gf) and crack opening displacement (COD) under conditions of tensile constraint in a notched asphalt binder sample in the brittle state with high reproducibility. A simple double-edge notched tension test can measure the essential and plastic works of fracture in the ductile state (we and wp) as well as the crack opening displacement (COD) providing measures of resistance to ductile failure. It has been established that a specification system based on these performance-based parameters (i.e., PG XX-YY, Gf, COD, we and wp) is able to provide superior performance grading for all binders, irrespective of their origin or method of manufacture.

Field Monitoring of Pavement Trial Sections

  • Binders of exact same AASHTO M320 grade can show very significant differences in transverse cracking.

  • Many binders crack at temperatures above their limiting BBR (AASHTO M320) or BBR + DTT (MP1a) temperatures.

    Laboratory Investigation

  • Physical aging, notch sensitivity, chemical aging (beyond RTFO/PAV), and traffic-induced fatigue cracking are likely contributing factors to premature transverse cracking.

  • Brittle and ductile fracture energies vary widely for binders of identical grade. How this affects cracking severity will be investigated with the newly constructed test roads.

1991 C-SHRP Trial on Highway 631

Hearst Hwy 631

C-SHRP (1991)

Timmins Hwy 655

(2003 & 2007)

750

1997

515

Cracks/km

2003

500

Bracebridge Hwy 118

(1994)

236

Lamont Hwy 637:02

C-SHRP (1991)

250

Ottawa Hwy 417 (2006)

74

49

14

5

2

5

0

Sections:

Toronto Hwy 427 (2008)

A

AA

BB

B

Petawawa

Hwy 17

SPS-9A

(1997)

M320 grades: 52-33 52-33.5 46-37 52-33

CGSB grades: 150-200B 150-200A 150-200AA 150-200B

A Total of 50 Test Sections Specifically

Dedicated to Low-Temperature Studies

Calculated Minimum Pavement Temperatures (Kapuskasing):

-32oC, -33oC (1994), -33oC (1996), -30oC (1999)… COLDEST: -33oC

Premature Cracking Due to Physical Aging

Morphology Relates to Performance …

Simple Performance-Based Binder Tests

Research Product: Three Test Methods

655-1

655-2

655-5

LS-308: Performance Grade of Physically Aged Asphalt Cement Using Extended Bending Beam Rheometer Method

LS-299: Asphalt Cement’s Resistance to Fatigue Fracture Using Double-Edge-Notched Tension (DENT) Test

LS-298: Asphalt Cement’s Resistance to Low Temperature Fracture Using Compact Tension (CT) Test

1996 SPS-9A Trial on Highway 17

Compact Tension

(LS-298)

Low Temperatures:

Brittle-to-Ductile Transition, Tgrade, after Physical Hardening

Fracture Energy, Gf, and Critical Crack Opening Displacement, COD, in Brittle State

Intermediate Temperatures:

Essential and Plastic Works

of Fracture, we and wp, and Critical Crack Opening Displacement, COD, in Ductile State

Extended BBR (LS-308)

180

2002

169

Cracks/km

2003

120

65

52

52

60

Aluminium Inserts

RR-4L

RR-7L

E-009

7

7

0

0

0

Double-Edge-Notched Tension (LS-299)

A Much Improved Binder Grading Method:

  • Determines an Accurate Grade Temperature

  • Assesses Binder Fracture Energies in Brittle and Ductile States

  • Accounts for the Effects of Physical Aging and Traffic

Sections:

02

03

60

61

L

AASHTO M320: -41 -35P -31 -35

MTO LS-308: -37 -29 -18 (!) -29

Ligaments (L): 5, 10, 15 and 20 mm

Calculated Minimum Pavement Temperatures (CFB Petawawa):

-24.7oC (1999), -26.5oC & -27.2oC (2003)… COLDEST: -27oC

But Is Hard to Quantify!

Asphalt Binder and Mixture Testing

Improved Prediction for Cracking Onset

Tests Show High Reproducibility and Ability to Discriminate Modification Technologies

Highway 118 and 17 Tests Sections That Cracked Prematurely

Compact Tension

Double-Edge-Notched Tension

SectionCracks/km

118-3 45

118-4 18

118-5 37

17-3 65

17-5 52

3 4 5 3 5 3 4 5 3 5 3 4 5 3 5 3 4 5 3 5 3 4 5 3 5

6.0

4.0

2.0

0.0

-20

-20

60

40

20

0

AAL + SBS(r)

+ SBS(l)

+ RET

+ SB(d)

+ PPA

DENT SBS(r) PG 70-28

100 mm/min

25oC

Force

(N)

-27

-27

COD

(cm)

T

grade

Cold

Lake

(oC)

Simple Performance Test

Compact Tension

Double-Edge-Notched Tension

-34

-34

Temperature Range for Start of Cracking

COLDEST: -27 C

-41

-41

M320-1h

MP1a-1h

LS-308-3d MP1a-3d G

-

3d

f

-40

-34

-28

-22

-20

15

5

10

20

0

one-hour soak three-day soak

AASHTO M320 Grade (oC)

Displacement (cm)

Grading Methods

Nature’s Way of Accelerated Pavement Testing in Northern Ontario

Large Range in Ductile Fracture Performance

Summary and Further Work

2003 Trial on Highway 655

10

Limiting Temperatures

April 2004 (8 months after construction) July 2005

Asphalt binders of the exact same AASHTO M320 grade

can perform very differently after long-term service.

December 2003 - February 2004

l

0

AASHTO M320:

58-35

52-35

64-36

64-36

64-36

64-35

64-35

MTO LS-308:

-10

58-29

52-29

64-34

64-26

64-32

64-30

64-31

Variations in physical aging and traffic-induced

fatigue are likely causes of accelerated transverse cracking.

l

l

1.5

1.5

T, oC

-20

Mix COD

(mm)

-30

1.06

Mix we

(kJ.m-2)

.99

Fracture energies in the brittle and ductile regimes vary

1.0

1.0

l

-40

.79

.77

depending on crude source and modification technology.

.71

.67

.63

.53

10

.52

.53

Comprehensive mixture tests and full-scale trials are ongoing

in Ontario to calibrate the newly proposed grading tests.

.51

.49

.43

l

.44

0.5

0.5

December 2004 - February 2005

0

T, oC

-10

Three test sections were badly damaged with a total of ~150 m of cracks after their first winter and ~300 m after their second winter. The cracking mainly occurred in the left (inner) wheel path of the south-bound lane due to heavy truck traffic and high thermal stresses. In spring 2005, several of the wheel path cracks had already started to sprout transverse cracks. The data in the next figure is able to explain the vast performance differences between binders of identical PG XX-34 AASHTO M320 grades.

0

Acknowledgments

0

-20

Cracking Distress

655-1

655-2

655-3

655-4

655-5

655-6

655-7

-30

Wheel Path, 2004 (m):

0

60

40

43

0

5

0

A. Andriescu, A. Basu, M. Gale, S. Iliuta, M.O. Marasteanu, P. Marks,

T. Masliwec, L.E. Moran, S.D. Roy, M.O. Zhao, and others.

Ministry of Transportation of Ontario,National Cooperative Highway

Research Program – Innovations Deserving Exploratory Analysis,

and Natural Sciences and Engineering Council of Canada

E.I. du Pont of Canada, Imperial Oil of Canada, and McAsphalt Industries

l

-40

Wheel Path, 2005 (m):

0

113

52

92

1

0

1

Only 4 months after construction the Highway 655 trial was hit with extreme temperatures. The surface reached a record low of –34oC twice in January 2004. So far the surface has reached below or near –30oC for a total of 15 times!

Both high essential works of fracture and crack opening displacements are desirable for resisting wheel path cracking which can seriously aggravate transverse cracking. The binder used in 655-1 physically ages less and the one used in 655-2 ages more compared to the others. (See Andriescu et al., AAPT 2005 and Bodley et al., AAPT 2007)

l

l


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