Influence of Coarse-Aggregate Angularity on Asphalt Mixture Macroperformance: Skid Resistance, High-Temperature, and Compaction Performance

Abstract

Macroperformance, i.e., skid resistance, high-temperature, and compaction performance, are related to the functional performance, safety, and durability of asphalt pavement. Currently, the research on such influencing factors focuses on the properties of asphalt, gradation composition, pavement structure, and so forth, whereas the geometrical characteristics of coarse aggregate, especially its angularity, has not gained due attention from researchers. This paper investigated the effects of coarse-aggregate angularity on the skid resistance, high-temperature performance, and compaction performance of asphalt mixtures. Three-dimensional angularity (3DA) computed by X-ray computed tomography (XCT) was employed to characterize coarse-aggregate angularity. Texture depth (TD) and British pendulum number (BPN) were evaluated through the sand patch test and the British pendulum test (BPT), respectively. The dynamic stability and rutting depth of mixtures with different coarse-aggregate angularities were examined with the wheel tracking test. The variation in height of the specimen with different angularity asphalt mixtures during the compaction process was tested through the Superpave gyratory compactor (SGC). The dynamic modulus (|E*|) of the asphalt mixtures was analyzed with the asphalt mixture performance tester (AMPT) and the generation of master curves. The results showed that three-dimensional (3D) angularity is able to characterize the angularity of the coarse aggregate. A lower coarse-aggregate angularity leads to a smaller skid resistance of the asphalt mixture. The angularity greatly influences the high-temperature and compaction performance of asphalt mixtures. Higher angularity leads to better high-temperature stability but causes difficulty in compaction. The angularity has a significant influence on the |E*| values of SMA-16 asphalt mixture. The results revealed that the decrease in coarse-aggregate angularity translated into a decrease in |E*| values on average. This study provides support for further research into and application of macroscopic properties of asphalt mixtures.