Fatigue Damage Self-Healing Analysis and the Occurrence of an Optimal Self-Healing Time in Asphalt Concrete

Abstract

Fatigue damage is one of the main distresses responsible for the deterioration of asphalt roads. Self-healing, occurring during rest periods, has been shown to increase the total number of loading cycles. The increase is assumed to depend on the time at which healing is induced and the healing duration. In the first damage stage, in which damage is caused by thixotropy, self-heating and permanent deformation, the recovery is equal to the reversible phenomena thixotropy and self-heating. In the second and third damage stages, the closure of cracks starts to dominantly contribute to the gain of additional loading cycles. The healable crack volume depends on the healing method and healing duration, and includes aspects of the crack type. If the healable volume is insufficient to completely close cracks, the healing efficiency decreases due to exponential crack growth. Other occurring phenomena related to the healing process, like thermal degradation, could lead to a further increase in loading cycles at the expense of other asphalt performance aspects. The heterogeneity of asphalt introduces uncertainty into measurements. Hence, the optimal healing time to induce healing for a maximum extension of loading cycles can be determined only in a range.