Investigating fatigue life prediction of rubber asphalt mixture based on damage evolution using residual strain analysis approach

This study aims to develop the fatigue life (Nf) prediction method of rubber asphalt mixture based on residual strain (RS) analysis by using three-point bending fatigue test. The RS mechanical model established based on the modified Burgers model was used to characterize the evolution laws of RS, the residual viscoelastic strain (RVES) and the residual viscous-flow strain (RVFS), and the mechanical parameter of residual strain ratio (RSR) was defined based on the evolution laws. The correlation analysis was performed to explore the relationship between the Nf and the RSR, and the damage indication was advanced. The damage variable was defined based on the RSR evolution and the established fatigue damage model based on the ExpAssoc damage evolution model was used to perform the damage evolution analysis. The correlation analysis between the RSR and the damage evolution speed (Ds) was conducted to establish the fatigue and remaining fatigue equations. The results showed that RS mainly consisted of RVES and RVFS, and the RVFS was primarily responsible for the material damage. The RS mechanical model can characterize the non-linear evolution laws of RS, RVES and RVFS with sufficient accuracy, and the RVES can be regarded as a constant under given conditions. The RSR characterizing Ds can determine damage evolution and Nf prediction, and define the damage variable by isolating the damage factor from the viscoelastic factor. The established damage model can be capable of capturing the damage evolution of the rubber asphalt mixture. The increased Ds led to the exhibited decrease in the Nf. The established fatigue equation and remaining fatigue equation succeeded in accurately predicting the Nf and remaining fatigue life (Nfr) corresponding to the early damage evolution stage of rubber asphalt mixture, respectively