Current Status for Multiple Stress Creep Recovery

October 9, 2008

NEAUPG Annual MeetingKarissa Mooney

MSCR Test – AASHTO TP70-07

• Measures percent recovery and non-recoverable creep compliance at 100 and 3200 Pa on RTFO residue material.

• The test determines the presence of an elastic response in an asphalt binder under shear creep and recovery.

MSCR Test – AASHTO TP70-07

Non-Recoverable Creep Compliance

- Measurement of permanent deformation- Defined as the residual % strain in a

specimen after a creep and recovery cycle divided by the stress applied.

- Jnr(N) = ε10/3.2

MSCR Test – AASHTO TP70-07• Test Parameters

– RTFO Aged Residue Material– DSR with 25 mm plate, 1 mm gap– Stress levels - 100 and 3200 Pa– Creep stress is applied for 1s– Recovery 9s– 10 cycles for each stress level– Service/Environmental Temperature

MSCR Test – AASHTO TP70-07

• Report Parameters– Average % recovery @ 100 and 3200 Pa– % Difference between average recovery at

100 and 3200 Pa– Jnr @ 100 and 3200 Pa– % Difference between average Jnr @ 100

and 3200 Pa

MSCR Binder Spec

– PG 64S-xx with Jnr3.2 < 4– PG 64H-xx with Jnr3.2 < 2– PG 64V-xx with Jnr3.2 < 1– PG 64E-xx with Jnr3.2 < 0.5

MSCR Binder Spec– (Jnr3.2-Jnr0.1)X100/Jnr0.1 <0.75 max– At environmental grade temperatures– Low temp BBR and DTT remain the same– PG 64S - G*sinδ (max = 5000 kPa)– PG 64HV - G*sinδ (max = 6000 kPa)

Original

RTFOT

1619222528H & V grade DSR G*sinδMax 6000

1619222528S grade DSR G*sinδMax 5000

PAV

6464 Very heavyMSCR3.2 <1.0

6464 Heavy MSCR 3.2<2.0

6464 Standard MSCR3.2 <4.0

64DSR G*/sinδMin 1.0

MSCR Binder Spec (D’Angelo)

Low temp BBR and DTT remain unchanged

[(MSCR3.2 [(MSCR3.2 ––MSCR 0.1)/ MSCR 0.1)/

MSCR 0.1] < .75MSCR 0.1] < .75

MSCR Binder Spec

• Standard Grade “S”– (Traffic levels - < 10 million ESALs)

• Heavy Grade “H”– (Traffic levels – 10 to 30 million ESALs)

• Very Heavy Grade “V”– (Traffic levels - > 30 million ESALs)

• Grade Bumping

Percent Recovery

A method to determine to presence of elastic response and stress dependence of PMA and unmodified binders.

εr(N) = ((ε1- ε10)*100)/ε1

MSCR Binder Spec

• MSCR % Recovery Guidelines– For “H” Grade – min % recovery 25%– For “V” Grade – min % recovery 35%

At a given Jnr value, the % recovery should fall above the Jnr-% recovery curve.

Specification Status

• AASHTO TP70-07– Proposed Changes

• % Recovery Plot• 4 Jnr limits (S, H, V, E)

• AASHTO M320– Table 3 (Approved by SOM Committee –

anticipated approval August 2009)

MSCR Test Results and Analysis

64S-22----1.587.3970

70V-2235%25.690.95570

64E-2245%92.690.34364Modified76-22

70S-22---0.983.00770

64H-22---5.181.1816470-22

64S-28---1.352.9256464-28

64S-22---0.113.1766464-22

AASHTO M320 -Table 3

Min. % Recovery

% Recovery

Jnr @ 3.2 kPa

Test Temp

AASHTO M320 -Table 2

MSCR Test Results and Analysis

355982

488076

608670 8780

858864PG82-22

(PG 70V-22 or

PG 76V-22)

ASTM % ER @

25C

AASHTO % ER @

25C

Min. % Recovery

% Recovery

@ 3.2 kPa

Test TempPG Grade

0

10

20

30

40

50

60

70

80

90

100

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2

Jnr

% R

ecov

ery

Passing % Recovery

Failing % Recovery

% Recovery Jnr0 2.125 235 140 0.550 0.2560 0.12575 0.0590 0.025

D’Angelo

Effect of Polymer Loading

3200 Pa100 Pa3200 Pa100 Pa

0.450.3735.5546.2464

Jnr 1/kPa% RecoveryTest Temp

0.240.1956.5364.3464

0.280.2349.1857.6664

0.720.5820.9031.8164

0.870.7115.0325.0564

1.080.949.6817.8764

MSCR Evaluation –Increased Polymer Loading

0

1020

30

40

5060

70

8090

100

0 0.5 1 1.5 2 2.5

Jnr Curve Jnr @ 3.2 Poly. (Jnr @ 3.2)

0

10

20

30

40

50

60

70

80

90

100

0 0.5 1 1.5 2 2.5

Jnr

% R

ecov

ery

and

Ela

stic

Rec

over

y

Jnr curve Jnr - SBS ER - SBS ER - SBS - Sasobit Jnr - SBS - Sasobit

MSCR – Rut Test Comparison

1.5566.178.50.08264-22E82-2264

1.6850.655.80.2464-22V76-2264

13.2---0.55.7470-22<S70-2274.7

5.1---1.22.9270-22S70-2270

3.5733.74.41.3564-22H70-2264.4

7.1---3.43.464-22S64-2264

Rut Depth @

10000 Passes

Min%

Recovery

% Recovery

Jnr @ Rut Test

Temp

PG Grade,

Jnr

PG GradeRut Test

-20

-15

-10

-5

0

RU

T D

EPT H

IN m

m

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000RUT PASSES AT ~64° C & 158 LBS (703 N)

NuStar Analysis, E-10 Fine, 64-22S @ 64.4°C, 158# AVERAGE BOTH WHEELSBRRS-3, E-10 Fine, 64-22H (70-22) (Citgo) @ 64.2°C @ 158# AVERAGE BOTH WHEELSNuStar, E-10 Fine, 64-22V (76-22) @ 64.0°C 158# AVERAGE BOTH WHEELSNuStar Analysis, E-10 Fine- NuStar 82-22 (64-22V) @ 64.2°C 158# AVERAGE BOTH WHE

NUSTAR STUDY PG 64-22S, 64-22H, 64-22V BINDERSTESTED IN HAMBURG

DRY AT ~ 64° C, 158# LOAD, E-10 FINE LIMESTONE BLEND

09/14/08 19:45:43 C:\DRIVE_E\PMW 2008\NUSTAR\NuStar Analysis, 64-22S, 64-22H, 64-22V @ ~64°C, 158#.spf

-20

-15

-10

-5

0

RU

T D

EPT H

IN m

m

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000RUT PASSES AT ~64° C & 158 LBS (703 N)

NuStar Analysis, E-10 Fine, 64-22S @ 64.4°C, 158# AVERAGE BOTH WHEELSBRRS-3, E-10 Fine, 64-22H (70-22) (Citgo) @ 64.2°C @ 158# AVERAGE BOTH WHEELSNuStar, E-10 Fine, 64-22V (76-22) @ 64.0°C 158# AVERAGE BOTH WHEELSNuStar Analysis, E-10 Fine- NuStar 82-22 (64-22V) @ 64.2°C 158# AVERAGE BOTH WHEBRRS-3, E-10 Fine, 70-22 (Citgo) @ 70.0°C @ 158# AVERAGE BOTH WHEELSBRRS-3, E-10 Fine, 70-22 (Citgo) @ 74.7°C @ 158# AVERAGE BOTH WHEELS

NUSTAR STUDY PG 64-22S, 64-22H, 64-22V BINDERSTESTED IN HAMBURG

DRY AT ~ 64° C, 158# LOAD, E-10 FINE LIMESTONE BLEND

9/14/08 20:03:29 C:\DRIVE_E\PMW 2008\NUSTAR\NuStar Analysis, 64-22S, 64-22H, 64-22V @ ~64°C, 158#

Stress Sensitivity of Jnr - PG 70-22

y = 0.0002x + 0.6713R2 = 0.6538

0.000

1.000

2.000

3.000

4.000

5.000

6.000

7.000

8.000

0 5000 10000 15000 20000 25000

Stress in kPa

Jnr,

in 1

/kPa

Jnr Linear (Jnr)

Stress Sensitivity of % Recovery - PG 70-22

y = 0.0639e-8E-05x

R2 = 0.3571

-20.00%

0.00%

20.00%

40.00%

60.00%

80.00%

100.00%

0 5000 10000 15000 20000 25000

Stress in kPa

% R

ecov

ery

% Recovery Expon. (% Recovery)

Stress Sensitivity of Jnr - PG 82-22

y = 6E-06x + 0.068R2 = 0.9407

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0 5000 10000 15000 20000 25000

Stress in kPa

Jnr,

in 1

/kPa

Jnr Linear (Jnr)

Stress Sensitivity of % Recovery - PG 82-22

y = 0.8189e-2E-05x

R2 = 0.9274

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

0 5000 10000 15000 20000 25000

Stress in kPa

% R

ecov

ery

% Recovery Expon. (% Recovery)

Binder ETG Summary

• D’Angelo presented the MSCR specifications and current results at ETG– Low Jnr produced low rutting with dry

Hamburg– At a certain stiffness level in the binder, the

rutting levels off– Percent recovery shows differences in cross-

linking

Starfield

Sand Paper

Total Florescence

Effects of Jnr with Binder Modification

4.2 @ 58C1.9 @ 52C-0.48 @ 58C1.3 @ 52C200 pen

@ 58C@ 52C3200 Pa100 PaPG58-34

1.290.4832.842.7SBS/Sulfur

Jnr 1/kPa @ 3200 Pa% Recovery @ 52CModification

1.790.6917.629.2SBS/PPA/Sulfur

0.950.342.462.8Elvaloy/PPA

20.88.8523.1PPA

Asphalt Institute Round Robin

• ASTM E691-05 Inter-lab study• RTFO aged binders @ 100 and 3200 kPa• Determine Jnr and % recovery• Developed repeatability and

reproducibility, d2s values

Asphalt Institute Round Robin

PAV DSR – 40%21%RecoveryRTFO DSR – 22%40%Jnr

Reproducibility – d2sPAV DSR – 14%12%RecoveryRTFO DSR – 9%24%Jnr

Current DSRMSCRRepeatability – d2s

Presented by Mike Anderson @ Binder ETG – Sept 08

Future Goals

• Jnr - % Recovery– Various Polymer/Additive Evaluation

• Round Robin for Suppliers/Users• Training/Workshops• Evaluation of required Grades for region• Implementation of AASHTO M320

Table 3