Fatigue-induced degradation of self-healing properties of asphalt mixtures: An energy-based characterization and a fatigue life prediction method

While the synergistic interaction between fatigue and self-healing influences the fatigue life, the accuracy of predictions is limited by the application of fixed healing parameters. To quantitatively analyze the fatigue-induced evolution of self-healing properties, this study simplified the indirect tensile (IDT) fatigue-healing test and developed a modified healing model. The effects of aging, dynamic water cycles, temperature, and loading level on the self-healing properties were also evaluated. Furthermore, a fatigue life prediction method incorporating quantifiable healing parameters is established within the hot mix asphalt fracture mechanics (HMA-FM) framework. Validation is performed by comparing the predicted and measured fatigue life from IDT fatigue tests, using laboratory and field-cored specimens. Results indicated that the normalized healing rate ( h r ) serves as a measure of self-healing degradation during fatigue, showing insensitivity to healing time. While limited aging increased the asphalt mixture's tensile strength and modulus, it reduced the self-healing properties and fatigue life. The self-healing properties decreased with dynamic water cycles, transitioning from an initial decline to a slower reduction. Although polymer-modified asphalt (PMA) had minimal effect on the healing rate at low stress levels, it markedly mitigated the degradation of self-healing property at high stress levels by retarding damage accumulation and aging. The logarithm of the predicted fatigue life varied linearly with aging, dynamic water cycles, and temperature. Of note, incorporating healing parameters improved fatigue life prediction accuracy by 24% to 45% compared to conventional models that lacked or employed fixed healing parameters.