Rheological analysis of multi-stress creep recovery (MSCR) test

It has been known for some time that the current AASHTO M 320-05 specification does not address the true rutting potential of modified asphalt binders. The multi-stress creep recovery (MSCR) test was proposed by the United States Federal Highway Administration to replace the AASHTO M 320-05 high-temperature specification parameter and various SHRP + test methods. The new parameter of non-recoverable compliance, Jnr, is currently being considered as a replacement for the Superpave high-temperature binder parameter of vertical bar G*vertical bar/sin delta (omega = 10rad/s) (AASHTO TP 70-09). An investigation of the suggested new parameter in capturing the rutting potential and a rheological analysis of the MSCR test method were carried out for conventional and modified asphalt binders and are reported in this paper. The laboratory wheel tracking test was conducted to study the rutting potential of asphalt mixes prepared with the same asphalt binders. Correlation of the new parameter, Jnr, with rutting in asphalt mixes is briefly discussed. A linear viscoelastic compliance model was developed to describe the MSCR test and is also discussed.