Geometrical characteristics of aggregates: The influence of sphericity, angularity, and surface texture on the workability of asphalt mixtures

Workability of asphalt mixtures is considered as an essential factor in quality control of asphalt pavement construction. However, there are fewer studies related to the influence of geometric properties of aggregates on the workability of asphalt mixture. The main purpose of this paper is to explore the influence of aggregate sphericity, angularity and surface texture on the workability of asphalt mixture during the mixing process. Firstly, a self-developed workability equipment of asphalt mixture was used to analyze the differences in the asphalt mixture workability of three materials, namely, basalt, limestone and pebble. Next, using the Aggregate Image Measurement System (AIMS), the geometric characteristics of the aggregates were determined. Accordingly, the correlation between the geometric characteristics of the aggregates and the workability index was established through linear correlation analysis. Finally, investigating the distribution uniformity of asphalt film by scanning electron microscope (SEM), the influence of the geometric characteristics of the aggregates on the workability of the asphalt mixture was determined. The results demonstrated that, compared with limestone and pebble asphalt mixtures, a significantly greater workability value was observed for the basalt asphalt mixture. Moreover, the geometric characteristics of the aggregates were found to influence the change rule of workability in the following order: sphericity > surface texture > angularity. Furthermore, the geometric characteristics revealed to have a significant effect on the uniformity of the asphalt film.