Effects of Coarse Aggregate Shape Parameters on Workability, Design, and Performance Characteristics of Stone Matrix Asphalt Mixes

The present study explores the effects of coarse aggregate shape characteristics on the performance of stone matrix asphalt (SMA) mixes. The aggregates were produced with two commonly using different crushing mechanisms, namely JH (jaw-horizontal shaft impactor) and JJV (jaw-jaw-vertical shaft impactor). The digital image based Aggregate Image Measurement System was used to capture aggregate shape parameters. The effects of aggregate shape on the SMA mix were captured via various indicators, such as workability, design (resilient and dynamic modulus), and performance parameters (i.e., shear, rutting, and fracture). The shape characterization showed that aggregate produced from JH had significantly higher angularity, texture, and flat and elongated particles compared to JJV. However, the JJV-produced aggregate had significantly higher sphericity/cubicity compared to JH. Moreover, the SMA mix derived from JJV offered better rutting and shear resistance, and modulus values, while both mixes (i.e., JH and JJV) showed a similar fracture resistance behavior. Conclusively, it was perceived that aggregates having high cubicity with moderate angularity and texture offered significantly improved performance. Therefore, it can be inferred that the type of crusher can significantly affect aggregate shape characteristics and the subsequent performance of SMA mixes.