Abstract
The objective of this study was to investigate the crack initiation behavior of asphalt mixtures and examine the fracture mechanism using dynamic semicircular bending (SCB) test. The scope of the study encompassed estimation of crack initiation parameter (Ni) and fatigue failure of six asphalt mixtures, including, conventional dense-graded (D) and rubber-modified gap-graded (AR) mixtures covering 144 SCB specimens. At 5°C, 15°C, and 25°C, D-mixes produced higher Ni than AR mixtures attributed to higher stiffness of D-mixes. Relative share analysis of Ni was found to be higher for D-mix than AR mixtures. Furthermore, correlation between |E*| and Ni indicated that higher stiffness of the mix resulted in brittle failure, which in turn increased the time for crack initiation to occur. Importantly, the stiffness of asphalt mixtures played a deciding role in contributing to the crack initiation phenomenon of these materials. Overall, the dynamic SCB test developed as part of the study was found to be a promising assessment technique to characterize crack initiation behavior of different types of asphalt mixtures.