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A New Test for Asphalt Quality:Asphalt Binder Cracking Device (ABCD)
Sang-Soo Kim, Ohio University
Ohio Asphalt Paving ConferenceFebruary 6, 2008
2
ScopeScope
BackgroundABCD Concept: Operating PrincipleDevelopment Of ABCDLaboratory ValidationField ValidationApplication
3
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.
4
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
5
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)
6
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.
7
Current ABCDSilicone Mold with Protrusions / Invar Ring
Current ABCDSilicone Mold with Protrusions / Invar Ring
Presence of hole in the sample significantly reduced variability
8
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
9
10
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
11
ABCD Test: Typical ResultsABCD Test: Typical Results
12
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
14
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
15
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
17
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
18
-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)
20
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
21
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
22
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
23
Errors in Sample PreparationErrors in Sample Preparation
Excessive Trimming
24
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
25
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
)
26
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
)
27
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
28
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
29
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
30
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
31
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
32
33
34
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
35
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
36
Thank You!Thank You!