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Multiple Stress Creep Recovery (MSCR) Testing Helps Predict Rutting

MSCR results for RET 
MSCR testing shows how repeated recovery from loads is a key to Elvaloy® RET's observed rut resistance.
Dynamic shear rheometry (DSR) methods have been refined recently, to better predict polymer-modified binder properties related to rutting and high temperatures. Current asphalt test standards now include AASHTO TP70, "Standard Method of Test for Multiple Stress Creep Recovery (MSCR) Test of Asphalt Binder Using a Dynamic Shear Rheometer (DSR)."

The MSCR test produces lab results that are closely correlated with actual mix performance. By dynamically loading the modified binder, and watching its accumulated "nonrecoverable creep compliance" (Jnr), the new test more accurate predicts polymer-modified binder performance, recognizing differences in polymer behavior at different temperatures and stress levels.

Using the MSCR test can often save money on polymer additives, by better matching the polymer level to needed performance. For an RET-modified binder, the test typically shows that very low levels of polymer can be used, to create binders that consistently outperform SBS and other modification methods.

"It is the Asphalt Institute’s opinion that MSCR represents a technical advancement over the current PG specification."

Bob Horan, P.E.
Regional Engineer
Asphalt Institute

From a presentation at the SEAUPG Annual Meeting, December 9, 2010, in Oklahoma City, Oklahoma » Download Asphalt Institute Guidance Document
Transportation Research Board Looks at Latest Binder Science
MSCR is one of advances discussed in this recent review of binder specifications and test programs by the TRB, a U.S. Government advisory council administered as part of the National Academies of Science. » Learn more