Evaluation of Low-Temperature Performance of SBS/CR Composite Modified-Asphalt Mixture under Aging and Freeze–Thaw Cycles

Abstract

To study the effects of aging and freeze–thaw cycles on the low-temperature performance of styrene–butadiene–styrene (SBS)/crumb rubber (CR) composite modified asphalt mixtures. Digital image correlation (DIC) technology was combined with the three-point bending test to compare the strain field changes of SBS/crumb rubber composite modified asphalt mixture (SBS/CRMA) and SBS-modified asphalt mixture (SBSMA) during loading. A new index, linear strain density (GE), is proposed to evaluate the crack resistance of asphalt mixtures; GE is the cumulative value of linear strain from loading to failure. In addition, using the bending beam rheometer (BBR) test and asphalt–aggregate contact angle test, the cracking characteristics of two kinds of asphalt mixtures under different conditions were analyzed from two aspects: low-temperature rheological properties, and adhesion and bond failure. The results indicated that the new index (GE) and the macroscopic index (FE) for evaluating the cracking characteristics of asphalt mixtures have a good correlation with BBR and contact angle test results. After aging and freeze–thaw cycles, the crack resistance and adhesion of the two modified asphalts decreased, decreasing the crack resistance of SBS/CRMA and SBSMA. Under the same conditions, the cracking resistance, aging resistance, and freeze–thaw resistance of SBS/CRMA were better than those of SBSMA. SBS/CRMA could better meet the demands of pavement materials in cold regions.