Rutting resistance and resilient modulus evaluation of polymer-modified SMA mixtures

摘要

Ethylene copolymer bitumen (ECB), namely Lucobit, as a thermoplastic polymer, SBS as a thermoplastic-elastomer polymer, and ethylene-vinyl-acetate (EVA) combined with Fischer-Tropsch wax and resin additives, namely Rheofalt WKR-2, as a modified thermoplastic polymer were used for stone matrix asphalt modification. Two types of asphalt modification processes including polymer-modified bitumen (PMB) and direct addition of polymer into mixture were employed and the effect of each one on resilient modulus and rutting resistance was evaluated by performing Indirect Tensile Resilient Modulus and Hamburg Wheel Tracking tests. PMB, SBS, and Rheofalt-modified mixtures resulted in lower rut depth and higher resilient modulus than did those modified by ECB. In direct addition of the polymer into mixture process, there is reduction in rutting resistance and resilient modulus of Rheofalt-modified mixtures in comparison with PMB. Furthermore, there was no improvement for ECB-modified mixtures by direct addition modification.