Influence of Coarse Aggregate Morphological Properties on the Performances of Warm-Mix Asphalt Containing Recycled Asphalt Pavement

AbstractThe properties of asphalt and aggregate in the warm-mix asphalt (WMA) containing recycled asphalt pavement (RAP) are critical to the mixture performances. This study quantified the effects of the morphological properties of WMA-containing RAP through the gray correlation analysis. The properties of asphalt and aggregate involved in this study included RAP content, two-dimensional morphological properties of recycled coarse aggregate, three-dimensional angle of recycled coarse aggregate, and surface free energy of recycled asphalt. The high-temperature performance represented by dynamic stability, low-temperature indicated by maximum bending strain, and moisture susceptibility characterized by the tensile strength ratio were chosen as the criteria for evaluating the impacts of different factors. The results showed that the RAP content had the greatest influence on high-temperature performance, followed by recycled asphalt’s surface free energy (SFE), and aggregate sphericity. The irregular shape factor of aggregate particles significantly influenced the mixture’s low-temperature properties. The SFE of asphalt was pivotal to the moisture susceptibility, and samples with higher SFE of asphalt presented better moisture damage resistance.