Laboratory Accelerated Testing of Traffic Polishing Effects on Asphalt Paving Mixtures

Abstract

Abstract Most laboratory polishing machines for pavement materials in use today are bulky and could not be easily fabricated in a typical pavement engineering laboratory. Most machines adopt a small-diameter circular-path polishing mode, which is different from actual field polishing actions, to save space and reduce test durations. Still, each test typically lasts longer than a day. To overcome the problems of test duration and polishing mode, this study developed a high-slip ratio linear-path polishing device to achieve a test duration of less than 4 h. The main research objectives were to study the polishing effects of different polishing modes and propose a polishing procedure to produce a polished state of British pendulum number (BPN) and mean texture depth (MTD) matching with field measured values. The four polishing modes studied were 1. dry polishing, 2. wet polishing, 3. dry polishing with sand, and 4. wet polishing with sand. The presence of water was found to have no statistically significant effect on the terminal BPN and MTD. When sand was applied, whether in dry (Mode 3) or wet (Mode 4) polishing, lower terminal MTD but higher BPN than those by Mode 1 or 2 were obtained. If polishing was continued without sand, the terminal BPN became lower than that achieved by Mode 1 or 2. Upon comparing laboratory polished BPNs with polished BPNs of in-service pavements, this study recommended the following two-stage mixed-mode polishing procedure: Mode 3 or 4 polishing with sand, followed by either Mode 1 or 2 polishing without sand.