Assessment of cracking performance indices of asphalt mixtures at intermediate temperatures

Abstract

ABSTRACT In recent years, two types of test methods have emerged to evaluate the susceptibility of asphalt mixtures to cracking at intermediate temperatures as part of performance-related mix design specifications: the indirect tensile (IDT) test and the semi-circular bending (SCB) test. In parallel, several associated analysis approaches have been utilised to evaluate cracking characteristics of these mixtures. The objective of this paper was to evaluate various cracking indices obtained from IDT and SCB tests in terms of their ability to provide a low-variability and high-discrimination response. In addition, the ranking potential of the considered indices in terms of cracking performance of asphalt mixtures was evaluated and inter-correlated. The cracking indices were able to capture the asphalt mixture performance with the fracture strain tolerance (FST) index and cracking resistance index (CRI) showing better performance when compared to other cracking indices. Generally, the IDT test results better distinguished the cracking performance of asphalt mixtures when compared to the SCB test results. The Ideal-CT index (CTindex) from the IDT test and the flexibility index (FI) from the SCB test demonstrated a fair correlation. Overall, the results demonstrated the suitability of both tests for predicting the cracking performance of asphalt mixtures at intermediate temperatures.