Multiple Stress Creep Recovery Test

The Multiple Stress Creep Recovery (MSCR) test measures how much an asphalt binder deforms permanently under repeated loading at high pavement temperature, and how much it springs back. It runs on the same Dynamic Shear Rheometer (DSR) used for other performance grading tests, but loads the binder far harder: instead of a tiny oscillation, it applies a steady shear stress for one second and then lets the binder recover. Its main result, Jnr, is the basis of the high-temperature grade in AASHTO M 332 (Federal Highway Administration, 2011¹). See Performance-Graded Binder Specifications Today for how the results are used.

The test is AASHTO T 350 (formerly the provisional TP 70) and ASTM D7405.

The Test

The test is run on binder aged in the Rolling Thin-Film Oven, which represents the binder just after construction, when rutting risk is highest. The specimen is a disc of binder between the DSR's 25 mm plates, set to a 1 mm gap, held at the test temperature. Under M 332 that temperature is the climate's high pavement temperature, for example 64°C (Federal Highway Administration, 2011¹).

Each loading cycle has two parts:

1. Creep: a constant shear stress is applied for 1 second, and the binder strains.
2. Recovery: the stress is removed for 9 seconds, and the binder recovers part of that strain.

The binder is put through 10 cycles at a low stress of 0.1 kPa, then immediately 10 cycles at a high stress of 3.2 kPa. At the low stress almost any binder behaves nearly elastically; at the high stress, the differences between binders, and especially between neat and polymer-modified binders, show up clearly.

Calculating the Results

For each cycle, three strains are read: the strain at the start of the cycle, $\varepsilon_0$; the strain at the end of the 1-second creep, $\varepsilon_c$; and the strain at the end of the 9-second recovery, $\varepsilon_r$. From these:

The percent recovery for the cycle is the share of the creep strain that the binder recovers:

The nonrecoverable creep compliance is the unrecovered strain divided by the applied stress:

Each value is averaged over the 10 cycles at each stress level, giving $R_{0.1}$, $R_{3.2}$, $J_{nr,0.1}$ and $J_{nr,3.2}$. The sensitivity of the binder to the higher stress is described by the percent difference in compliance:

A low Jnr means the binder leaves little permanent strain behind each load, so the mixture made with it should resist rutting. A high percent recovery at 3.2 kPa shows a strong delayed elastic response, which is the signature of a well-formed polymer network (Federal Highway Administration, 2011¹).

Why the Test Discriminates

The older high-temperature parameter, G/sin δ, is measured at strains small enough that a polymer network barely stretches. The binder's measured stiffness then reflects the polymer only as a filler. The MSCR test's 3.2 kPa stress strains the binder enough to engage the polymer, so two binders with the same G/sin δ can have very different Jnr and recovery. In the example published by FHWA, two binders made from the same base with the same 4 percent SBS polymer, one blended well and one poorly, had nearly the same conventional high-temperature grade, but percent recoveries at 3.2 kPa of about 40 and 19 percent (Federal Highway Administration, 2011¹).

Practical Points

• Temperature control matters more than in most DSR tests, because Jnr changes rapidly with temperature.
• Specimen preparation follows the DSR practice: avoid trapped air, trim the edge cleanly, and keep the thermal history consistent.
• Highly modified binders can show very low Jnr and very high recovery. Results at the low stress for such binders are near the limit of what the test resolves, which is one reason later editions of M 332 changed how Jnrdiff is applied.

Standard Test Methods

• AASHTO T 350, ASTM D7405: Multiple stress creep recovery test of asphalt binder using a DSR
• AASHTO T 240: Rolling thin-film oven test
• AASHTO M 332: Performance-graded asphalt binder using the MSCR test

@misc{pavint-multiple-stress-creep-recovery-test,
  author = {{Pavement Interactive}},
  title = {Multiple Stress Creep Recovery Test},
  year = {2026},
  publisher = {HeadLight},
  howpublished = {\url{https://pavementinteractive.org/reference-desk/testing/binder-tests/multiple-stress-creep-recovery-test/}},
  note = {Accessed [date]}
}