Investigation of fatigue cracks on RAP mixtures containing Sasobit and crumb rubber based on fracture energy

Fatigue cracking, rutting and low temperature cracking are three major distresses of asphalt mixtures. In last years, different methods based on fracture mechanic have been developed to measure performance of asphalt mixtures due to cracking. In this study, fracture mechanic method developed by Roque et al. has been employed to evaluate fatigue cracking performance of modified asphalt mixtures. Samples containing Reclaimed Asphalt Pavement (RAP) with different percentages of Sasobit (as a Warm Mix Asphalt additive) and crumb rubber were built. Resilient Modulus, static creep and Indirect Tensile (IDT) tests also conducted on samples and Resilient Modulus, creep compliance and Indirect Tensile Strength were measured. Based on fracture mechanic, Dissipated Creep Strain Energy (DCSE) was calculated for each sample, and fatigue strength of mixtures were investigated. The results indicated that the use of RAP, crumb rubber and Sasobit simultaneously caused desirable fatigue performance of modified mixtures. These mixtures had better Resilient Modulus and more loading capacity, as well as, lower cumulative damage rates rather than virgin sample. The ITS results also indicated more appreciable improvement in crack initiation threshold, Fracture Energy (FE) and Energy Ratio (ER).