Improving toughness of epoxy asphalt binder with reactive epoxidized SBS

TLDR: In this article, a reactive thermoplastic elastomer, epoxidized styrene-butadiene-styrene copolymer (ESBS) was introduced into epoxy asphalt binder (EAB).

Abstract: Brittleness is an inherent shortcoming of epoxy resin which results in the longitudinal fatigue cracking of mixtures during the long service time of orthotropic steel deck bridges. In this paper, this problem was addressed by introducing a reactive thermoplastic elastomer, epoxidized styrene–butadiene–styrene copolymer (ESBS) into epoxy asphalt binder (EAB). Epoxy ESBS modified asphalts (EESBAs) with various epoxidation degrees were prepared. Double phase separation occurred in the EESBAs. In the EESBAs with 18% and 31% epoxidation degrees, most of ESBS domains dispersed on the edge of the secondary asphalt phase and in the epoxy phase. Furthermore, the size and number of ESBS domains decreased in the epoxidation degree. However, un-epoxidized SBS domains completely dispersed the asphalt phase and all ESBS domains moved to the epoxy phase when the epoxidation degree increased to 39%. In EESBAs, the average diameters of asphalt domains increased in the epoxidation degree. The inclusion of ESBS increased the viscosity of the pure EAB and the viscosity of EESBAs increased in the epoxidation degree. Nevertheless, all EESBAs had at least a 150-min allowable construction time. By adding 2 wt% ESBS with 39% epoxidation degree, the glass transition temperature (Tg) decreased. The Tg of EESBAs decreased in the epoxidation degree. The inclusion of ESBS greatly enhanced the damping properties of the pure EAB. The elongation at break and toughness of the pure EAB were remarkably increased by 263% and 93%, respectively, with the incorporation of 2 wt% ESBS with 39% epoxidation degree. Furthermore, the toughness of EESBAs increased in the epoxidation degree.