Description
The Multiple Stress Creep Recovery (MSCR) test has received increased attention by agencies as a means to specify and purchase asphalt cement binder. These agencies are using the protocol to either grade all asphalt cements or only as a means to screen for modification. The Arizona Department of Transportation is one agency that has been examining this protocol. The principal type of modified asphalt cement used in the state is a terminal blended rubber with polymer additive, referred to as a TR+ binder. In this paper, these binders have been tested and evaluated to determine their MSCR based performance grade and also to see if the MSCR test can detect the presence of the rubber and polymer additive. Limited comparisons are drawn between the TR+ binders and other, polymer only modified asphalts. It is found that the TR+ binders generally grade at a higher traffic level in the MSCR based system and also that the MSCR test detects the presence of the modifier.
