Kinetics-based fatigue damage investigation of asphalt mixture through residual strain analysis using indirect tensile fatigue test

Fatigue damage, one of the major distresses of asphalt pavement, has been found to have a phenomenological correlation with the accumulated residual strain (RS) of the asphalt mixture tested by stress-controlled fatigue test with excessive creep. However, it remains a challenge to quantitatively model such phenomenological correlation. This study aims to address this challenge by applying the kinetics theory to the indirect tensile fatigue test (ITFT) with excessive creep data of various asphalt mixtures. First, ITFTs of asphalt mixtures under different conditions were conducted to analyze the RS response. Then, the RS kinetics model was established based on the fast-constant rate kinetics model. Finally, two of the kinetics model parameters, the RS constant rate (k_c) and activation energy, were successfully applied to characterize the fatigue life (N_f) and the fatigue damage resistance of the asphalt mixture, respectively. It was found that the established RS kinetics model can accurately describe the development of the accumulated RS determined by ITFT. The k_c determined by ITFT is an effective indicator for the rate of the initial damage evolving to the failure threshold. The established k_c-based fatigue equation can be used to predict the N_f of the asphalt mixture tested by ITFT from k_c. The RS accumulation activation energy can effectively characterize the fatigue damage resistance of the asphalt mixture tested by ITFT.