Multiple Stress Creep Recovery Test to Differentiate Polymer Modified Bitumen at High Temperature

Abstract The constant demand for high-performing and more reliable roads has led to an increasing use of complex bituminous binders such as polymer-modified bituminous binders, which has become a widespread practice for asphalt pavement. As a result, specification and testing have evolved to better distinguish between quality materials. In recent years, more focus has been devoted to better evaluating the rutting resistance of bituminous binders. The multiple stress creep recovery (MSCR) test has gained popularity over the last decade, especially for polymer-modified binders, bringing more advantages in discriminating amongst quality binders such as polymer-modified bitumen. Within the International Union of Laboratories and Experts in Construction Materials, Systems and Structures technical committee 272, Phase and Interphase of Behavior of Innovative bituminous Materials, and its TG1 task group, several binders were thoroughly evaluated, including two non-modified and two polymer-modified bituminous binders, under various testing conditions to address the high-temperature behavior. Five laboratories performed MSCR on short-term aged binders after performing the rolling thin film oven test, in the same temperature conditions for all binders. Despite the limited data set, the variability between laboratories was reasonable. The MSCR results were compared with softening point temperature, high-temperature performance grade criteria, |G*| / sinδ, and equi-modulus temperature. MSCR was able to distinguish between complex binders better as compared with conventional parameters. It generates multiple useful parameters, amongst which percent recovery and non-recoverable creep compliance are the most relevant. This paper presents the analysis of MSCR results and comparison with other test methods.