A New Test for Asphalt Quality:Asphalt Binder Cracking Device (ABCD)

Sang-Soo Kim, Ohio University

Ohio Asphalt Paving ConferenceFebruary 6, 2008

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ScopeScope

BackgroundABCD Concept: Operating PrincipleDevelopment Of ABCDLaboratory ValidationField ValidationApplication

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ABCD: Asphalt Binder Cracking DeviceNCHRP-IDEA #99

ABCD: Asphalt Binder Cracking DeviceNCHRP-IDEA #99

ABCD: To minimize Low Temperature Thermal Cracking,one of major failure types of asphalt pavements.

Nationally, tens of billion dollars are spent to fix the cracked pavement every year.

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AASHTO M320 (Table 1)AASHTO M320 (Table 1)

Assumes Strength & CTE are constant

Cracking temperature depends on binder stiffness (BBR)

Does not work for modified binders; a(T)

Thermal Stress,

Strength

Temperature

Strength

Stress

SoftStiff

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AASHTO M320 (Table 2)AASHTO M320 (Table 2)

Thermal Stress,

Strength

Temperature

Stress

Strength

Assumes CTE is constant; Strength is not constant

Cracking temperature depends on binder stiffness (BBR) and strength (DTT)

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electrical strain gaugeinvar ring

asphalt

ABCD Concept: Operating PrincipleABCD Concept: Operating Principle

Coefficient of Thermal Expansion/Contraction

Asphalt = 200 x 10-6 m/m/C

Invar Ring = 1.4 x 10-6 m/m/C

When temperature drops, asphalt shrinks 100 times or more than the ABCD invar ring. Asphalt compresses the ring. The Electrical Strain Gauge measures this compression. When it cracks, the compression disappears.

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Current ABCDSilicone Mold with Protrusions / Invar Ring

Current ABCDSilicone Mold with Protrusions / Invar Ring

Presence of hole in the sample significantly reduced variability

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Stress Distribution on Specimen Prepared with Silicone Mold (for 1.0 MPa Average Stress)

Stress Distribution on Specimen Prepared with Silicone Mold (for 1.0 MPa Average Stress)

Invar Ring

Asphalt

Hole in Sample

2.02 MPa

0.82 MPa

0.64 MPa

1.57 MPa

Stress Distribution

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ABCD DevelopmentABCD Development

Current ABCD

Silicone Mold & Invar Ring

One Hole in Specimen

Start right after trimming at room temperature

Cooling: 20C -20C in 1 hr; From -20C, 10C/hr

Tcr Standard Deviation = 0.5~1.0C

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ABCD Test: Typical ResultsABCD Test: Typical Results

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Advantage of ABCDAdvantage of ABCD

Simple procedure

Single equipment

Stiffness, strength, CTE are accounted for close to field conditions

Test is forgiving

Simultaneous testing of several samples

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LAB STUDY #1: FHWA Modified BindersLAB STUDY #1: FHWA Modified Binders

0

1

2

3

4

5

6

7

8

9

-45 -40 -35 -30 -25

ABCD Fracture Temperature, C

Frac

ture

Stre

ss (A

BC

D),

MP

a .

Unm 70-22

Unm 64-28

CMCRA

Air-Blow n

Flux

MRL 191

EVA

SBS R G

SBS L

SBS L G

EVA G

ESIPolymer Modified

No Polymer Except CMCRA

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Role of PolymerRole of Polymer

0

1

2

3

4

5

6

7

8

9

-50 -45 -40 -35 -30 -25

ABCD Fracture Temperature, C

Aver

age

(Max

) Fra

ctur

e St

ress

(ABC

D),

MPa

.

PG Binder (FHWA)PG Binder (CA)Roofing FluxRoofing Coat

Polymer Modified

silicone mold, invar ring, 10C/hr

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Pearson Correlation: FHWA Modified Binders

Pearson Correlation: FHWA Modified Binders

ABCDM320-2(ABCD) M320-2 M320-1 S m

ABCD 1M320-2 (ABCD) 0.98 1

M320-2 0.71 0.72 1

M320-1 0.83 0.85 0.90 1

S (BBR) 0.87 0.86 0.91 0.92 1

m-value (BBR) 0.69 0.69 0.82 0.92 0.78 1

TSRST 0.91 0.94 0.69 0.86 0.84 0.73

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LAB STUDY #2: Polymer ConcentrationLAB STUDY #2: Polymer Concentration

M320-1 ABCD

PG Grade Tcr°C

Strain, με(strength)

Base 44.5 - 41.5 -44.2 21

Base+2% SBS 53.1 - 41.7 -46.5 36

Base+3% SBS 57.4 - 41.4 -48.0 40

Base+4% SBS 63.3 - 39.3 -51.1 43

Base+5% SBS 70.0 - 38.1 -54.1 53

Binder

Binders were prepared by ExxonMobil ABCD results Triplicate samples

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0

10

20

30

40

50

60

-55 -50 -45 -40

ABCD Cracking Temp, C

ABC

D F

ract

ure

Stra

in, m

icro

s

Base

3%

5%

4% 2%SBS

ABCD on SBS ConcentrationABCD on SBS Concentration

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-55

-50

-45

-40

-35

0 1 2 3 4 5 6

SBS Content, %

Cra

ckin

g Te

mp,

C

M320-1ABCD

SBS Concentration vs. Cracking TempSBS Concentration vs. Cracking Temp

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Polymer Modification Field Trials (138 data)Polymer Modification Field Trials (138 data)Asphalt Institute, Engineering Report -215, (2005) Quantification of the Effects of Polymer-Modified Asphalt (page 18)

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Validation #1: Pennsylvania Test RoadValidation #1: Pennsylvania Test Road

Constructed in 1976 using 6 AC-20 binders

Sections T1 & T5 cracked 4 month later

Air Temperature = -29C

Pavement Temperature = -23C

Sections T2, T4, T6 cracked after 4 years

Section T3 never cracked for 7 years

Overlaid 1984

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ABCD Results: PA RTFO ResidueABCD Results: PA RTFO Residue

RTFO (1st Try) RTFO (2nd Try)1 2 Avg 1 2 3 Avg

T1 -21.8 Broken -21.8 -21.3 -22.2 - -21.8T2 -34.7 -34.6 -34.7 -34.0 -34.1 -34.4 -34.2T3 -33.2 - -33.2 - - - -T4 -31.1 -32.9 -32.0 -32.0 -32.5 - -32.3T5 -23.2 -26.8 -25.0 -26.0 -25.6 - -25.8T6 -33.1 -34.8 -34.0 -33.6 -33.5 - -33.6

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ABCD Results: PA PAV ResidueABCD Results: PA PAV Residue

1. Trimming error2. Eccentricity: Ring was off-centered by about 1 mm.

PAVSections 1 2 Avg

T1 -23.1 -21.71 -22.4T2 -28.21 -31.1 -29.7T3 -30.7 -30.72 -30.7T4 -28.5 -29.8 -29.2T5 -25.2 -24.4 -24.8T6 -32.9 -31.6 -32.3

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Errors in Sample PreparationErrors in Sample Preparation

Excessive Trimming

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Cracking Index (7yr) vs ABCD (PAV)Cracking Index (7yr) vs ABCD (PAV)

y = 8.91x + 288.02R2 = 0.94

0

20

40

60

80

100

-35 -30 -25 -20

ABCD (PAV) Tcr, C

Cra

ckin

g In

dex

(7yr

)

T6

T3

T2T4

T5

T1

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Cracking Index (7yr) vs M320-1 (PAV)Cracking Index (7yr) vs M320-1 (PAV)

y = 4.93x + 148.09R2 = 0.35

0

20

40

60

80

100

-30 -25 -20 -15

AASHTO M320; BBR (PAV) Tcr, C

Cra

ckin

g In

dex

(7yr

)

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Cracking Index (7yr) vs BBR Stiffness (PAV)Cracking Index (7yr) vs BBR Stiffness (PAV)

y = 7.14x + 224.07R2 = 0.77

0

20

40

60

80

100

-35 -30 -25 -20 -15

BBR Stiffness (PAV) Tcr, C

Cra

ckin

g In

dex

(7yr

)

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TSRST VS ABCD (PAV)TSRST VS ABCD (PAV)

y = 0.54x - 10.29R2 = 0.83

y = 0.74x - 2.16R2 = 0.85

-35

-30

-25

-20

-15

-45 -40 -35 -30 -25 -20

ABCD (PAV)

TSR

ST,

C

FHWA StudyPA Study

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Validation #2: Lamont Test RoadValidation #2: Lamont Test Road

y = 18.952x + 740.13R2 = 0.9157

-50

0

50

100

150

200

-41 -39 -37 -35 -33 -31 -29 -27

ABCD Tcr, C

Ther

mal

Cra

cks

/km

(200

3)

Lamont Test Road

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Validation #3: Highway 17 (SPS-9A) near Petawawa Ontario

Validation #3: Highway 17 (SPS-9A) near Petawawa Ontario

y = 8.8599x + 415.43R2 = 0.7979

-20

0

20

40

60

80

100

120

140

160

180

-50 -45 -40 -35 -30

ABCD Tcr, C

Cra

ck/k

m (2

003)

Highway 17, Ontario

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Critical Temperature vs. Cracking Index of Test Pavements

Coefficient of Determination (R2)

Critical Temperature vs. Cracking Index of Test Pavements

Coefficient of Determination (R2)

Test Roads ABCD M320-1 M320-2

Elk Co, PA 0.94 0.21 0.95Lamont 0.92 0.79 0.76

Highway 17 0.80 0.92 0.56

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ABCD Commercialization TimelineABCD Commercialization Timeline

Commercialization by EZ Asphalt Technology, LLC. through Highways for LIFE Technology Partnership Program

$239,000 Grant

Ruggedness Test by October 2008

ABCD Commercial Products by End of 2008

Round Robin Tests (10 labs) During 2009

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SummarySummary

Good correlation between ABCD and Pennsylvania Test Road performanceGood correlation between ABCD and TSRSTAble to characterize polymer modified bindersImproved repeatability: ~1.0C or less for binders testedABCD test is simple and forgivingSturdy ABCD ring

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AcknowledgementAcknowledgement

NCHRP-IDEA #99 (Inam Jawed, Ed Harrigan)David Powers (Ohio DOT)Highways for LIFE (Julie Zirlin, Sarah Tarpgaard)Tom Harman (FHWA)Aroon Shenoy (FHWA)Jack Youtcheff (FHWA)John D’Angelo (FHWA)Dean Maurer (Penn DOT)Kai Tam (Ontario MOT)Simon Hesp (Queen’s Univ.)Olga Puzic (ExxonMobil)Asphalt Institute

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Thank You!Thank You!