Performance evaluation of asphalt mixture using brake pad waste as mineral filler

The failed brake pads have been recognized as a kind of solid waste, which result in serious environmental problem. In order to provide an approach for treating the brake pad waste (BPW), this paper investigated the feasibility of using BPW as mineral filler in asphalt mixture. Firstly, BPW was laboratory manufactured into powder with a size lesser than 0.075 mm. Then, the effect of BPW powder on the physical and rheological properties of asphalt mortar was studied by the softening point test, the penetration test, the rotation viscosity test, and the dynamic shear rheological (DSR) test. The results showed that the addition of BPW powder could improve the viscosity and high temperature performance of asphalt mortar. Finally, the influence of BPW powder on the mechanical properties of asphalt mixture was analyzed by the Hamburg wheel tracking test, the accelerated freezing-thawing test, the dynamic uniaxial compression test, the semi-circular bending test and the four-point bending fatigue test. Although the low temperature property of WBP mixture was worse than the control asphalt mixture with limestone filler, BPW mixture has better anti-moisture, anti-rutting and fatigue properties. Asphalt mixture containing BPW filler showed satisfactory performance improvement.