Fatigue-Damage Model of a Pothole-Repairing Composite Structure for Asphalt Pavement

Abstract

Cumulative fatigue damage caused by repeated loads is one of the important factors that leads to formation of asphalt pavement potholes after they have been repaired. Investigations show that a recurring pothole often starts along the bonding surface between the repairing material and the original asphalt pavement, and the bonding failure is closely related to the repetitive effect of the traffic load. This phenomenon indicates that fatigue damage exists along the bonding surface of pothole repairing structure. It involves fatigue resistance of the asphalt mix and the bonding material. The fatigue process of the asphalt mix can usually be divided into three stages of deceleration fatigue, constant-speed fatigue, and accelerated fatigue. Until now, the accelerated fatigue stage has not been precisely characterized. Based on the existing fatigue theory, the effects of material damage on pothole repairing structures were analyzed in this paper. The analysis was conducted on repairing composite beams by establishing a nonlinear viscoelastic-viscoplastic fatigue damage constitutive model. Three kinds of bonding materials were used in the composite beams to make a bonding property comparison. Results show that fatigue lives of repairing composite beams are typically affected by the bonding material and the stress ratio. The fatigue strain rate is correlated with the change of the stress ratio. Compared with previous models, the strain-fatigue life curve produced by the proposed model is better matched with test results. It is also proved that the proposed model can precisely describe the deceleration, constant-speed, and acceleration stages of fatigue damage, especially the third stage.