Multiple Stress Creep Recovery (MSCR) characterization of polymer modified asphalt binder containing wax additives

Abstract

The effect of wax additives on the characteristics of polymer modified asphalt (PMA) binders (SIS, SBS and CRM) was investigated in this study. The binders were blended using the two wax additives (LEADCAP and Sasobit) and then artificially aged using rolling thin film oven (RTFO) and pressure aging vessel (PAV) procedures. Superpave binder tests were conducted to determine viscosity, G∗/sin δ, G∗sin δ and stiffness values. Multiple Stress Creep Recovery (MSCR) test was carried out to evaluate the rutting resistance properties, in original and RTFO aged states. In general the results showed that (1) after the addition of wax additives, the viscosity of PG 64-22 and PMA binders was decreased; (2) higher cracking resistance (i.e., lower stiffness and G∗sin δ values) was observed at the binders with LEADCAP; (3) by adding the wax additives, the percentage increase of rutting resistance (G∗/sin δ) was found to be higher for PG 64-22 binder, compared to the PMA binders; (4) it was found that the effect of wax additives cannot be identified using MSCR test results; (5) the MSCR test was observed to be potentially inappropriate to measure the rutting performance of CRM binder.