Evaluation and characterization of properties of crumb rubber/SBS modified asphalt

Abstract

This research studies the effects of SBS copolymer and asphalt compositions on the properties of CR/SBS modified asphalts prepared by the terminal blend (TB) method. These CR/SBS modified asphalts, also called TB binders, were prepared by blending 20 wt% CR powders with two base asphalts and various amounts of SBS copolymers. The samples were subjected to conventional, rheological, force-ductility, rotational viscosity, thermal storage, and fluorescence microscopy tests. The results show that TB rubberized binders have superior properties to unmodified asphalts. The properties of TB rubberized asphalts were further improved by adding SBS copolymers, indicating that this is a feasible way to produce high-performance binders. However, the extent of improvement induced by SBS copolymer addition was less than that induced by CR addition. Activation energy (Ea) results suggest that this may be because the SBS copolymers do not form a polymer network structure throughout the asphalt. Moreover, the properties of TB binders are also affected by the asphalt composition. In terms of their stability index (SI) values, TB binders with various SBS contents showed good storage stability. Fluorescence observations revealed the state of rubber and SBS copolymer dispersion in the asphalt matrix, providing an explanation for the improved storage stability and confirming the deductions drawn from the Ea data. In conclusion, TB asphalt technology combined with SBS modification shows great potential to produce high-performance and cost-effective asphalt binders.