Evaluation of Coarse Aggregates using Three-Wheel Polishing Device and Field Friction Assessment

Abstract: The enhancement of surface friction in asphalt mixtures can significantly reduce or prevent accidents on wet pavements. However, current hot mix asphalt (HMA) design procedures do not explicitly include friction as a design criterion. It is well established that the frictional properties of coarse aggregates in wearing course mixtures are crucial for improving pavement surface friction. This study aimed to utilize a three-wheel polishing device (TWPD) to assess the polishing and skidding resistance of coarse aggregates and to develop a predictive model for evaluating asphalt pavement skid resistance based on laboratory tests. To achieve this, seven coarse aggregate samples, directly sourced from various asphalt plants, were selected to create laboratory aggregate rings for TWPD polishing tests according to AASHTO PP103 standards. The dynamic friction tester (DFT) and circular texture meter (CTM) were used to assess the micro and macro textures of the aggregates during polishing. Additionally, field friction measurements, including DFT, CTM, British pendulum tester (BPT), and locked wheel skid tester (LWST), were performed on asphalt pavements containing the tested aggregates. Correlations were developed between the lab and field test results. Specifically, a model was constructed to predict field DFT values from lab-tested aggregate DFT results, and a correlation was established to estimate field skid resistance (LWST results) using various lab and field aggregate and mixture properties.