Laboratory evaluation of the effect of gilsonite on the performance of stone matrix asphalt mixtures

This study investigates the benefits of modifying asphalt and stone matrix asphalt (SMA) mixtures in flexible pavement. Sixty to seventy penetration-grade asphalt cement and Iranian natural bitumen (gilsonite) were subjected to physical and performance tests. Physical and conventional tests were conducted on modified and unmodified bitumen (penetration, softening point, ductility and viscosity). Performance tests, including Marshall stability, indirect tensile strength, moisture susceptibility, resilient modulus and rutting resistance, were conducted on unmodified and modified SMA mixtures. Results of conducted tests on the modified asphalt binders with 5%, 10% and 15% gilsonite show that using gilsonite improves performance of SMA mixture.