Standard Method of Test for

Multiple Stress Creep Recovery

(MSCR) Test of Asphalt Binder
Using a Dynamic Shear
Rheometer (DSR)

AASHTO Designation: TP 70-10

American Association of State Highway and Transportation Officials

444 North Capitol Street N.W., Suite 249
Washington, D.C. 20001
Standard Method of Test for

Multiple Stress Creep Recovery (MSCR) Test

of Asphalt Binder Using a Dynamic Shear
Rheometer (DSR)

AASHTO Designation: TP 70-10

1. SCOPE

1.1. This test method covers the determination of percent recovery and non-recoverable creep
compliance of asphalt binders by means of the Multiple Stress Creep Recovery (MSCR) test. The
MSCR test is conducted using the Dynamic Shear Rheometer (DSR) at a specified temperature. It
is intended for use with residue from T 240 (Rolling Thin-Film Oven Test (RTFOT)).
Note 1—The majority of the development work on this test method was performed on material
conditioned according to T 240 (RTFO).

1.2. The percent recovery value is intended to provide a means for determining the elastic response and
stress dependence of polymer modified and unmodified asphalt binders.

1.3. The values stated in SI units are to be regarded as the standard.

1.4. This standard does not purport to address all of the safety concerns, if any, associated with its use.
It is the responsibility of the user of this standard to establish appropriate safety and health
practices and determine the applicability of regulatory limitations prior to use.

2. REFERENCED DOCUMENTS

2.1. AASHTO Standards:

 M 320, Performance-Graded Asphalt Binder
 MP 19, Performance-Graded Asphalt Binder Using Multiple Stress Creep Recovery (MSCR)
Test
 T 240, Effect of Heat and Air on a Moving Film of Asphalt Binder (Rolling Thin-Film
Oven Test)
 T 315, Determining the Rheological Properties of Asphalt Binder Using a Dynamic Shear
Rheometer (DSR)

2.2. ASTM Standard:

 D 8, Standard Terminology Relating to Materials for Roads and Pavements

TS-2b TP 70-1 AASHTO

© 2010 by the American Association of State Highway and Transportation Officials.
All rights reserved. Duplication is a violation of applicable law.
3. TERMINOLOGY

3.1. Definitions:

3.1.1. Definitions of terms used in this practice may be found in ASTM D 8, determined from common
English usage, or combinations of both.

3.2. Definitions of Terms Specific to This Standard:

3.2.1. creep and recovery—a standard rheological test protocol whereby a specimen is subjected to a
constant load for a fixed time period and then allowed to recover at a constant zero load for a fixed
time period.

3.2.2. non-recoverable creep compliance (Jnr)—the residual strain in a specimen after a creep and
recovery cycle divided by the stress applied, kPa–1.

4. SUMMARY OF TEST METHOD

4.1. This test method is used to determine the presence of elastic response in an asphalt binder under
shear creep and recovery at two stress levels at a specified temperature. For performance-graded
(PG) asphalt binders, the specified temperature will typically be the PG high temperature from
MP 19, Table 1.

4.2. Asphalt binder is first conditioned using T 240 (RTFOT). A sample of the RTFO-conditioned
asphalt is tested using T 315 (DSR). The 25-mm parallel plate geometry is used with a 1-mm gap
setting. The sample is tested in creep at two stress levels followed by recovery at each stress level.
The stress levels used are 0.1 kPa and 3.2 kPa. The creep portion of the test lasts for 1 second,
which is followed by a 9-second recovery. Ten creep and recovery cycles are tested at each stress
level.

5. SIGNIFICANCE AND USE

5.1. This method is designed to identify the presence of elastic response in a binder and the change in
elastic response at two different stress levels while being subjected to ten cycles of creep stress
and recovery. Non-recoverable creep compliance has been shown to be an indicator of the
resistance of an asphalt binder to permanent deformation under repeated load.

6. APPARATUS

6.1. Use the apparatus as specified in T 315.

7. PROCEDURE

7.1. Conditioning—Condition the asphalt binder in accordance with T 240 (RTFOT).

7.2. Sample preparation—The sample for the MSCR test is prepared the same as samples for T 315
using 25-mm plates. The temperature control will also follow the T 315 requirements.

TS-2b TP 70-2 AASHTO

© 2010 by the American Association of State Highway and Transportation Officials.
All rights reserved. Duplication is a violation of applicable law.
7.2.1. This test may be performed on the same sample that was previously used to determine the DSR
properties of the RTFO residue as specified in M 320. When using the previously tested sample to
perform this test, a 1-minute relaxation period between the tests is required before running this
test. When using a new sample to perform this test, the 1-minute relaxation period is not required.

7.3. Test protocol—The test is performed at the selected temperature using a constant stress creep of
1.0-second duration followed by a zero stress recovery of 9.0-second duration. The test is
performed at two stress levels, 0.1 kPa and 3.2 kPa. Ten cycles are run at each of the two stress
levels for a total of 20 cycles. The commanded full stress for each creep cycle shall be achieved
within 0.03 second from the start of the creep cycle as certified by the equipment manufacturer.
The stress and strain shall be recorded at least every 0.1 second for the creep cycle and at least
every 0.45 second for the recovery cycle on an accumulated basis such that, in addition to other
data points, the data points at 1.0 second and 10.0 second for each cycle’s local time are explicitly
recorded. If the DSR does not record the strain at exactly 1.00 and 10.00 seconds, then the
software shall extrapolate prior data to determine the strain value at 1.00 second and
10.00 seconds. Extrapolated data shall include a measured data point no more than 0.05 second
prior to the required time for a creep cycle and no more than 0.30 second prior to the required time
for a recovery cycle. There are no rest periods between creep and recovery cycles or changes in
stress level. The total time required to complete the two-step creep and recovery test is
200 seconds.

7.4. Analysis—Analyze and record the creep and recovered percent strain for the 0.1 kPa and 3.2 kPa
creep stress levels as follows:

7.4.1. For each of the ten cycles, record the following:

7.4.1.1. The initial strain value at the beginning of the creep portion of each cycle. This strain shall be
denoted as ∈0.

7.4.1.2. The strain value at the end of the creep portion (i.e., after 1.0 second) of each cycle. This strain
shall be denoted as ∈c.

7.4.1.3. The adjusted strain value at the end of the creep portion (i.e., after 1.0 second) of each cycle (∈1),
which is calculated as follows:
∈1 = ∈ c – ∈ 0

7.4.1.4. The strain value at the end of the recovery portion (i.e., after 10.0 second) of each cycle. This
strain shall be denoted as ∈r.

7.4.1.5. The adjusted strain value at the end of the recovery portion (i.e., after 10.0 seconds) of each cycle
(∈10), which is calculated as follows:
∈10 = ∈r – ∈0

7.4.2. For each of the ten cycles, calculate the following at the creep stress level of 0.1 kPa:

7.4.2.1. Percent recovery ∈r(0.1, N) for N = 1 to 10:

(∈1 − ∈10 ) × 100
∈r ( 0.1, N ) =
∈1

7.4.3. For each of the ten cycles, calculate the following at the creep stress level of 3.2 kPa:

TS-2b TP 70-3 AASHTO

© 2010 by the American Association of State Highway and Transportation Officials.
All rights reserved. Duplication is a violation of applicable law.
7.4.3.1. Percent recovery ∈r(3.2, N) for N = 1 to 10:
(∈1 − ∈10 ) × 100
∈r ( 3.2, N ) =
∈1

8. CALCULATION

8.1. Using the results obtained in Sections 7.4.2.1 and 7.4.3.1, determine the average percent recovery
for the asphalt binder at creep stress levels of 0.1 kPa and 3.2 kPa as shown in the following
equations:

8.1.1. Calculate average percent recovery at 0.1 kPa:

SUM ⎡⎣∈r ( 0.1, N ) ⎤⎦
R0.1 = for N = 1 to 10
10

8.1.2. Calculate average percent recovery at 3.2 kPa:

SUM ⎡⎣∈r ( 3.2, N ) ⎤⎦
R3.2 = for N = 1 to 10
10

8.1.3. Calculate percent difference in recovery between 0.1 kPa and 3.2 kPa:

Rdiff =
[ R0.1 − R3.2 ] × 100
R0.1

8.2. Using the results obtained in Sections 7.4.2.1 and 7.4.3.1, determine the non-recoverable creep
compliance between 0.1 kPa and 3.2 kPa as shown in the following equations:

8.2.1. For each of the ten cycles at a creep stress of 0.1 kPa, calculate the non-recoverable creep
compliance, Jnr(0.1, N), kPa–1, as strain/stress:
∈10
J nr ( 0.1, N ) =
0.1

8.2.2. For each of the ten cycles at a creep stress of 3.2 kPa, calculate the non-recoverable creep
compliance, Jnr(3.2, N), kPa–1, as strain/stress:
∈10
J nr ( 3.2, N ) =
3.2

8.2.3. Calculate the average non-recoverable creep compliance at 0.1 kPa, J nr0.1 , kPa–1:

SUM ⎡⎣ J nr ( 0.1, N ) ⎤⎦
J nr0.1 = for N = 1 to 10
10

8.2.4. Calculate the average non-recoverable creep compliance at 3.2 kPa, J nr3.2 , kPa–1:

SUM ⎡⎣ J nr ( 3.2, N ) ⎤⎦
J nr3.2 = for N = 1 to 10
10

TS-2b TP 70-4 AASHTO

© 2010 by the American Association of State Highway and Transportation Officials.
All rights reserved. Duplication is a violation of applicable law.
8.2.5. Calculate the percent difference in non-recoverable creep compliance between 0.1 kPa and
3.2 kPa, J nrdiff :

⎡ J nr − J nr ⎤ × 100
J nrdiff = ⎣
3.2 0.1 ⎦

J nr0.1

9. REPORT

9.1. Report the following information:

9.1.1. Sample identification;

9.1.2. PG grade and test temperature, nearest 0.1°C;

9.1.3. Average percent recovery at 0.1 kPa, R0.1;

9.1.4. Average percent recovery at 3.2 kPa, R3.2;

9.1.5. Percentage difference between average percent recovery at 0.1 kPa and 3.2 kPa, Rdiff.

9.1.6. Non-recoverable creep compliance at 0.1 kPa, J nr0.1 , to two significant digits, kPa–1;

9.1.7. Non-recoverable creep compliance at 3.2 kPa, J nr3.2 , to two significant digits, kPa–1; and

9.1.8. Percent difference between non-recoverable creep compliance at 0.1 kPa and 3.2 kPa, J nrdiff , to
nearest 0.1 percent.

10. PRECISION AND BIAS

10.1. Precision—The research required to develop precision estimates has not been conducted.

10.2. Bias—The research required to establish the bias has not been conducted.

11. KEYWORDS

11.1. Asphalt binders; creep and recovery; creep compliance; Dynamic Shear Rheometer (DSR);
elastomer identification; Multiple Stress Creep and Recovery (MSCR) Test; percent recovery;
polymer modification.

TS-2b TP 70-5 AASHTO

© 2010 by the American Association of State Highway and Transportation Officials.
All rights reserved. Duplication is a violation of applicable law.
APPENDIXES
(Nonmandatory Information)

X1. SAMPLE CALCULATIONS

X1.1. A typical test data plot consisting of ten cycles of creep and recovery at 0.1 kPa creep stress is
shown in Figure X1.1. The plot for 3.2 kPa creep stress is similar to Figure X1.1 and will not be
shown here. Test data from cycle number 9 are plotted in Figure X1.2 for further clarification.

Figure X1.1—Test Data Plot Showing Typical Ten Cycles of Creep and Recovery at Creep Stress of 0.1 kPa

X1.2. Sample Calculations:

X1.2.1. Calculation of percent recovery for cycle number 9 (see Figure X1.2):
1. Determine strain at the start (initial strain): ∈0 = 183%
2. Determine strain at 1-second creep end time point: ∈c = 212%
3. Determine adjusted creep end strain at 1-second point: ∈1 = (∈c – ∈0) = (212 –
183)% = 29%
4. Determine strain at 10-second recovery end time point: ∈r = 206.0%
5. Determine adjusted recovery end strain at 10-second point:

∈10 = (∈r – ∈0) = (206 – 183)% = 23%

6. Determine percent recovery for cycle number 9 at 0.1 kPa creep stress, ∈r(0.1, 9):

TS-2b TP 70-6 AASHTO

© 2010 by the American Association of State Highway and Transportation Officials.
All rights reserved. Duplication is a violation of applicable law.
 (∈1 − ∈10 ) × 100
∈r ( 0.1, N ) =
∈1
For cycle number 9 at a creep stress level of 0.1 kPa, the percent recovery will be:
(29 − 23) × 100
= 21%
29.0

Figure X1.2—Test Cycle No. 9 Data Plot Showing Creep and Recovery at Creep Stress of 0.1 kPa

X1.3. Follow the above example to calculate percent recoveries for all ten cycles for both creep stress
levels of 0.1 kPa and 3.2 kPa.

X2. INDICATIONS OF ELASTIC RESPONSE

X2.1. The percent recovery is intended to provide a means for determining the presence of elastic
response and stress dependence of polymer modified and unmodified asphalt binders. Figure X2.1
may be used as an indicator of the presence of an elastomeric polymer.

TS-2b TP 70-7 AASHTO

© 2010 by the American Association of State Highway and Transportation Officials.
All rights reserved. Duplication is a violation of applicable law.
 100

90

80
y = 29.371x –0.2633
70
Passing % recovery
% recovery

60

50

40

30

20
Failing % recovery
10

0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1

Jnr, kPa
Figure X2.1—Non-recoverable creep compliance versus percent recovery

X2.2. On the graph in Figure X2.1, plot the average percent recovery at 3.2 kPa, R3.2, versus the average
non-recoverable creep compliance at 3.2 kPa, J nr3.2 , measured at the same temperature.

X2.3. If the plotted point falls above the line on the graph, the indication is that the asphalt binder is
modified with an acceptable elastomeric polymer. If the plotted point falls below the line on the
graph, the indication is that the asphalt binder is not modified with an elastomeric polymer.

TS-2b TP 70-8 AASHTO

© 2010 by the American Association of State Highway and Transportation Officials.
All rights reserved. Duplication is a violation of applicable law.