Effects of Binder Modification on Rutting Performance of Asphalt Binders

Asphalt binder is the driving economical factor in asphalt pavement design. As a result, it is a good target to optimize the design by minimizing the overall cost while maximizing the performance. Modifying asphalt binders with polymers has been historically a successful method of optimization of pavement design. However, fluctuations in polymer prices and concerns related to sustainability lead many engineers to consider scrap tire rubber as a full or partial replacement of the polymers. Polymer coated rubber (PCR), a hybrid blend of crumb rubber and polymer, is a relatively new alternative material to improve asphalt mixture performance. The objective of the study reported in this paper is to investigate the relative performances of the neat asphalt binder, polymer modified (PM) binder and PCR modified binder using the wet process (PCR-Wet). The influence of the modifications on the viscosity, stiffness and rutting performance were explored. The experimental program included rotational viscosity measurements, linear viscoelastic characterization using frequency sweep (|G*|) test and rutting resistance using multiple stress recovery (MSCR) test on the base binder and the PCR modified binder. Findings from this study suggest that the more sustainable and rut-resistant asphalt binders can be achieved by using the PCR-Wet process.