Multiple stress creep recovery, run in a DSR on RTFO-aged binder at the high pavement temperature. The sample is loaded for 1 second and allowed to recover for 9 seconds, through a series of cycles at 0.1 kPa and then 3.2 kPa, giving non-recoverable creep compliance (Jnr) and percent recovery. Lower Jnr means less rutting, and the grade adds a traffic letter, S, H, V or E, so a binder graded for extremely heavy traffic reads PG 64E-22.
MSCR recovery's 78 percent, that's real polymer in there, not some stiffened-up base binder dressed up as a 76.
Also heard as
- multiple stress creep recovery
Related terms
DSR
Dynamic shear rheometer: the instrument that measures a binder's stiffness and elasticity by twisting a thin disk of it.
Polymer-modified asphalt
Binder blended with an elastic polymer, usually SBS, to resist rutting in heat and cracking in cold.
PG
Performance Grade: the binder rating that names the hottest and coldest pavement temperatures a binder can handle.
Rutting
Channel-shaped depressions that form in the wheel paths as the pavement deforms under repeated loads.