Binder ETG:ABCD Project Update

(NCHRP-99)

Binder ETG:Binder ETG:ABCD Project UpdateABCD Project Update

(NCHRP(NCHRP--99)99)SangSang--SooSoo KimKim

Ohio UniversityOhio UniversitySeptember 27, 2004September 27, 2004

Acknowledgement• NCHRP-IDEA

– Inam Jawed– Ed Harrigan

• FHWA– Tom Harman– Aroon Shenoy– Jack Youtcheff

• ExxonMobile– Olga Puzic

Asphalt Binder Cracking Device (ABCD)

• To Determine Thermal Cracking Potential of Asphalt Binder

• An Alternative Superpave Binder Specification

AASHTO M320 (MP1)Assume Strength is Constant

(and/or Consider Failure Strain)

Thermal Stress,

Strength

Temperature

Strength

Stress

AASHTO MP1aStrength is Not Constant

Thermal Stress,

Strength

Stress

Strength

Temperature

Outline• Earlier ABCD

– Aluminum Mold & Aluminum Ring– Round Specimen

• Current ABCD– Silicone Mold & Invar Ring– Holes in Specimen

Earlier ABCDAluminum Mold & Ring

ABCD Test

PAV B 6230

-600

-500

-400

-300

-200

-100

0

-60 -50 -40 -30 -20

Temperature, C

Unc

orre

cted

Stra

in, µ

ε

Calibration

ABCD Test: Corrected Strain

-200

-150

-100

-50

0

50

-65 -55 -45 -35 -25

Temperature, C

Cor

rect

ed S

trai

n, µ

ε

B6230SBS Linear: -58C

Repeatability Results

0.0

0.5

1.0

1.5

2.0

2.5

3.0

-62 -57 -52 -47 -42 -37 -32Fracture Temperature, C

Frac

ture

Stre

ss, M

Pa

PAV PG 58-28PAV PG 70-28

round aluminum moldaluminum ABCD ring10 C/hr

Repeatability ResultsRound Al-Mold/Ring

What’s Happening?• Examine B6227 (Air Blown) which has

the largest variation (s = 8.2C).• Compare Theoretical and Measured

Thermal Stress.• Need to Develop a Thermal Stress

Calculation Program

OU Program vs TSAR

0

4

8

12

16

20

-40 -35 -30 -25 -20 -15 -10

Temperature, C

Ther

mal

Stre

ss, M

Pa

OUTSAR

Binder FHWA 6225 PC=23 on OU program

Alpha = 170 microstrain/CCooling Rate = 1C/hourStep Cool = 0.2C

Typical CTE• Tg is located near

the low end PG grade (Nam&Bahia).

• B6227 = PG70-28• CTE of AC with -

28C Tg

Data from Bahia & Anderson (1993)

0.0003

0.0004

0.0005

0.0006

-50 -30 -10 10 30

Temp, C

Vol

umet

ric T

herm

al E

xpan

sion

C

oeffi

cien

t, m

/m/C

AAA-1 (Tg = -28.2C)

AAK-1 (Tg = -16.5C)

MP1a (Constant)

B6227 Thermal Stress

0

1

2

3

4

5

-60 -55 -50 -45 -40 -35

Temperature, C

Stre

ss, M

Pa

ABCD (fracture measured)Predict (alpha=170)Predict (Vary alpha of AAA1)

B6227 Air Blown

Random Effects in Fracture Properties (Ferry)

Fracture Strength and Strain Are • Time and Temperature Dependent.• Affected by (Macro- and) Micro-scopic

Inhomogeneities.

The measured strength is always much lower than the strength calculated from the Primary Bond Strength.

Current ABCD:Specimen Geometry

Silicone Mold

Current ABCD:Current ABCD:Specimen GeometrySpecimen Geometry

Silicone MoldSilicone Mold

Silicone Mold with Protrusions

Why Silicone Mold?• To Introduce Uniform

Inhomogeneities– Mix Contains Inhomogeneities– Known Stress Concentration– Known Location of Fracture

• To Minimize Handling of Specimen (Test without Removing Mold)

• Silicone Mold is Still Flexible at -60C

Effect of Silicone Mold on Strain of Ring

-50

0

50

100

150

200

250

300

350

400

-55 -50 -45 -40 -35 -30 -25 -20 -15Temperature, C

Stra

in, µ

ε

Soft Si Mold w/ Ring (top)Stiff Si Mold w/ Ring(bottom)

Invar Ring Only (center)

Difference b/t Soft Mold w/ ring and Invar Ring Difference b/t Stiff Mold

w/ ring and Invar Ring

Stress Distribution on Specimen Prepared with Si Mold

Invar Ring

Asphalt

Hole in Sample

2.02MPa

0.82MPa

0.64MPa

1.57MPa

Stress Distribution

ABCD Repeatability:Silicone MoldABCD Cracking Temperature, °C

IDTrial 1 Trial 2 Avg

02-059 -28.5 -28.5 -28.5 0.0

02-061 (1) -31.3 -33.1 -32.2 1.3

02-061 (2) -32.2 -32.9 -32.6 0.5

02-129 -21.8 -23.5 -22.7 1.2

02-130 -25.8 -26.9 -26.3 0.8

02-209 -28.6 -29.4 -29.0 0.5

02-058 -47.0 -47.9 -47.5 0.7

02-060 -40.7 -40.9 -40.8 0.1

02-129 -37.9 -39.8 -38.9 1.4

02-130 -35.9 -37.1 -36.5 0.8

02-206 -38.3 -41.6 -40.0 2.3

02-207 -39.7 -39.8 -39.8 0.1

02-210 -38.1 -39.8 -38.9 1.3

Flux

Coating

Std. Dev.°C

FHWA Binder ABCD (Silicone) Results 1

• Comparison with FHWA-RD-02-074 Report– TSRST– MP1a– MP1– BBR Stiffness & m-value

FHWA BindersFHWA ID Description

B6224 flux

B6225 unmodified base (PG 64-28)

B6226 unmodified high grade (PG 70-22)

B6227 air-blown

B6229 styrene-butadiene-styrene (SBS) linear grafted

B6230 styrene-butadiene-styrene (SBS) linear

B6231 styrene-butadiene-styrene (SBS) radial grafted

B6232 ethylene vinyl acetate (EVA)

B6233 ethylene vinyl acetate (EVA) grafted

B6243 ethylene styrene interpolymer (ESI)

B6251 chemically modified crumb rubber asphalt (CMCRA)

AMRL 191 AASHTO Materials Reference Library #191

Pearson Correlation

ABCDMP1a

(ABCD) MP1a MP1 S m

ABCD 1

MP1a (ABCD) 0.98 1

MP1a 0.71 0.72 1

MP1 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

ABCD vs TSRST

y = 0.56x - 8.86R2 = 0.99

-44

-39

-34

-29

-24

-44 -39 -34 -29 -24

ABCD

TSR

ST SBS R G

SBS L G

EVA GSBS L

EVAAirBlown

Unm BaseUnm High

R2=0.83when SBS L G and CMCRA are included

without SBS LG & CMCRA

CMCRA

ESI

TSRST vs MP1a

y = 0.87x - 1.87R2 = 0.82

-35

-33

-31

-29

-27

-25

-23

-35 -33 -31 -29 -27 -25 -23

MP1a

TSR

ST

SBS R G

SBS L G

EVA G

SBS L

AirBlown

Unm Base

Unm High

CMCRA

ESI

EVA

Without ESI

TSRST vs BBR Stiffness

y = 1.47x + 16.47R2 = 0.93

-35

-33

-31

-29

-27

-25

-23

-35 -33 -31 -29 -27 -25 -23

S (BBR)

TSR

ST

SBS R G

SBS L G

EVA G

SBS L

EVA

AirBlown Unm Base

Unm High

ESI

CMCRA

Without ESI, CMCRA

ABCD (Silicone) vs DTT

ABCD vs MP1a(ABCD)

y = 0.9441x + 2.7716R2 = 0.9643

-45

-40

-35

-30

-25

-20

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

ABCD

MP

1a(A

BC

D)

TSRST vs MP1a(ABCD)

y = 0.6115x - 15.001R2 = 0.8894

-34

-29

-24

-19

-14

-34 -29 -24 -19 -14

MP1a(ABCD) PC=23

TSR

ST

FHWA Binder ABCD (Silicone) Results 2

ABCD (invar ring, silicone mold) test on FHWA binders0

1

2

3

4

5

6

7

8

9

-45 -40 -35 -30 -25

Temperature, C

Max

Fra

ctur

e S

tress

(AB

CD

), M

Pa

191 6224 62256226 6227 62296230 6231 62326233 6243 6251

Fracture Temp & Stress

0

1

2

3

4

5

6

7

8

9

-45 -40 -35 -30 -25

ABCD Fracture Temperature, C

Ave

rage

(Max

) Fra

ctur

e S

tress

(AB

CD

), M

Pa

.

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

Role 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

Effects of CTE• Asphalt Binder • ABCD Rings• Aggregates

Binder CTEs

0.0

0.5

1.0

1.5

2.0

2.5

-50 -45 -40 -35 -30 -25 -20 -15 -10

Temp, C

Ther

mal

Stre

ss, M

Pa

Alpha = 170 microstrain/CAlpha=117 microstrain/CVarying Alpha (Tg = -28.2C, AAA1)

Binder FHWA 6225 (PG 64-28, unm)PC=1 1 C/hour rate

ABCD Ring CTEs 1

-45

-40

-35

-30

0 5 10 15 20 25

ABCD Ring Coefficient of Thermal Expansion (10-6/C)

AB

CD

Cra

ckin

g Te

mpe

ratu

re, C

PG 58-28 (PAV)

PG 70-28 (PAV)

Invar

Steel

Aluminum

Invar

Steel

Aluminum

ABCD Ring CTEs 2

0.0

0.5

1.0

1.5

2.0

2.5

3.0

-45 -40 -35 -30 -25 -20 -15 -10

Temp, C

Ave

rage

The

rmal

Stre

ss, M

Pa

Invar Ring (alpha vary AAA1)Steel Ring (alpha vary AAA1)Al Ring (alpha vary AAA1)

Binder FHWA 6225 10 C/hrPC=1 on OU Program

PG 58-28

PG 70-28

Aggregate CTEs

0

1

2

3

4

-40 -35 -30 -25 -20 -15 -10

Temp, C

Ther

mal

Stre

ss, M

Pa

ABCD: Invar Ring (alpha vary AAA1)TSRST: Agg a=6 (alpha vary AAA1)TSRST: Agg a=12 (alpha vary AAA1)

Binder FHWA B 6225 PC=1 on OU Program10 C/hr

Conclusions 1• Silicone mold improved repeatability• Polymer modification increased the

strength and, in turn, lowered the cracking temperature

• ABCD highly correlated with TSRST• MP1a using ABCD strength showed

the best correlation with TSRST

Conclusions 2• Theoretically calculated thermal

stress agreed well with the measured with ABCD

• Effects of CTE were significant and needs further evaluation

Work Plan

• Test Binders from Various Sources• ABCD Hardware Upgrade for More

Accurate Strength Measurements• Refine Test Procedure

Thanks!

Three Binders• Two PG Binders

– PG 70-28 SBS modified– PG 58-28 unmodified

• FHWA Binders• Roofing Binders

– 7 Fluxes– 5 Coatings

ABCD Results:FHWA Binders

• Poor repeatability– Cracking Temp = 4.1C– Fracture Strength = 0.71 MPa

• Coefficient of Determinations (r2)– With TSRST = 0.62– With MP1a = 0.53

FHWA Binder Results 1

0

1

2

3

4

-60 -50 -40 -30Fracture Temperature, C

Frac

ture

Stre

ss, M

Pa

622462256226

6227622962306231

62326233

FHWA Binder Results 2

1.0

1.5

2.0

2.5

-55 -45 -35Avg Fracture T (ABCD), C

Avg

F S

tress

(AB

CD

), M

Pa

Flux

Unm High

Unm BaseAirBlown

EVA

SBS L G

SBS R G

EVA GSBS L

ABCD (round) vs. DTT

0

2

4

6

8

1.0 1.5 2.0 2.5Fracture Stress (ABCD), MPa

Fr S

tress

(DT)

, MP

a

DT (-24C)DT (-18C)DT (-12C)

ABCD Ring CTEs 3

Cracking Temperature Increase from Aluminum Ring Results, °CCTE

µε/°C

Measured AvgFracture Stress

MPa

MeasuredAvg Cracking

Temp, °C Measured Predicted*

PG 58-28 (PAV) tested with stiff silicone mold

Aluminum 24.0 1.26 -33.0 0.0 0.0

Steel 12.0 1.23 -31.8 1.2 0.9

Invar 1.4 1.53 -30.6 2.4 1.6

PG 70-28 (PAV) tested with stiff silicone mold

Aluminum 24.0 2.39 -43.0 0.0 0.0

Steel 12.0 2.25 -41.6 1.4 1.3

Invar 1.4 2.72 -39.0 4.0 2.2