Evaluation of the terminal blend crumb rubber/SBS composite modified asphalt

Abstract

Abstract Terminal Blend rubberized asphalt (TBRA) is a novel application of Crumb Rubber (CR) modified asphalt. Compared with traditional CR modified asphalt, TBRA has good storage stability with a lower viscosity. However, TBRA generally has inferior high temperature performance, thereby SBS polymer is usually incorporated for composite modification. This paper evaluates the performances of TB/SBS composite modified asphalt with various modification formulas. Different rubber contents and SBS polymer contents were considered. Low temperature performance grading test, thermal stress master curve and low temperature Semi-Circular Bend (SCB) test were conducted for low-temperature performance evaluation. Multiple Stress Creep and Recovery (MSCR) and Hamburg Wheel Tracking (HWT) test were conducted for high-temperature performance evaluation. The results show that a 2% SBS addition can enhance the rutting resistance and moisture resistance of TBRA mixture without impairing its low-temperature performances. But more SBS introduction is not putting much extra value. Also, it is observed that with the presence of chemically active SBS polymer, rubber molecules from TB process also take part in the polymer crosslinking networking and strengthen the mixture. Based on both performance evaluation and cost analysis, a 10%TB plus 2%SBS formula is recommended in this study.