Evaluation of multiple stress creep and recovery (MSCR) data for Arizona

In the recently released AASHTO M332 asphalt binder specification, the Multiple Stress Creep and Recovery (MSCR) test replaces the current modulus and phase angle based method used for high temperature characterization. In anticipation of possible future adoption of this standard, the Arizona Department of Transportation (ADOT) has cataloged Multiple Stress Creep and Recovery (MSCR) test results on more than 375 different asphalt binder samples dating back to 2008. In this paper, this database is reviewed to evaluate potential implications of the adoption of a revised grading procedure based on the outcomes from the MSCR test. The database is graded in both the current and the M332 system to compare temporal changes in asphalt binder under both systems. The standard is then evaluated for its ability to detect polymer modified asphalt binder supplied in Arizona, and for the interaction between grade and temperature. It is found that under the M332 system the number of required grades for the state of Arizona would increase from the current number of eight to a total of fourteen. Future work includes the reduction of the total number of grades through engineering judgment and knowledge of asphalt binder selection based on local Arizona conditions. Under this review, Arizona asphalt binder suppliers may not necessarily have to add additional storage capacity to their facilities to accommodate a transition to the M332 standard.