Material Design and Mechanism Explanation of Epoxy Asphalt Toughened with SBS/CR and CSR

Abstract

As a potential long-life pavement material, the high brittleness of epoxy asphalt prevents its application. Recycled from waste tires, crumb rubber (CR) can be used with styrene-butadiene-styrene (SBS) to prepare SBS/CR composite modified asphalt. The main objective of this paper is to conduct the material design of epoxy asphalt with SBS, CR, and core-shell rubber (CSR) to toughen the epoxy asphalt and enhance its performance. First, SBS modified epoxy asphalt and SBS/CR composite modified epoxy asphalt (CMEA) were prepared to optimize the toughening materials based on tensile tests. Subsequently, based on the optimized material, the optimal proportion was determined through the response surface method by the Design-Expert software. Third, the microscopic morphology of different epoxy asphalt was observed by laser scanning confocal microscopy (LSCM), and the changes in functional groups were tracked using Fourier transform infrared spectroscopy to reveal the toughening mechanism. Finally, the viscosity test was carried out on the optimal SBS/CR-CSR CMEA at different temperatures to determine its mixing temperature and allowable time. The results show that the SBS/CR-CSR CMEA is the best toughening method, and the optimal epoxy and CSR proportion is 37% and 12%, respectively. Its tensile strength increases by 467.11% and elongation at break increases by 68.73% compared with unmodified epoxy asphalt. The formation of interpenetrating polymer network structure between the SBS/CR network and epoxy resin network, as well as the change in the benzene ring that determines the softness and toughness, may be the main strengthening and toughening mechanisms. The suitable mixing temperature is 160°C for the optimal SBS/CR-CSR CMEA in this paper, which reduces about 20°C compared with conventional CR or SBS/CR composite modified asphalt, providing better environmental benefits. Overall, the SBS/CR-CSR CMEA presents a new solution for the promotion and application of epoxy asphalt.