Laboratory Investigation for the Road Performance of Asphalt Mixtures Modified by Rock Asphalt-Styrene Butadiene Rubber

In this paper, styrene butadiene rubber (SBR) was utilized to improve the low-temperature performance of Buton-rock asphalt (BRA)-modified asphalt. Firstly, the optimum content of SBR modifier agent was determined by basic mechanical property tests, including penetration, ductility, and soft point tests. The comprehensive road performance, including high- and low-temperature performance, moisture resistance, and antifatigue performance at a low-temperature condition, of SBR-BRA-modified asphalt mixtures was evaluated by comparison with a base asphalt mixture, SBR-modified asphalt mixture, BRA-modified asphalt, and styrene-butadiene-styrene (SBS)-modified asphalt mixture. The fatigue test under the experimental temperature of -10 degrees C and loading frequencies of 0.01, 0.1, 1, 5, and 10 Hz were designed to evaluate the antifatigue capacity of SBR-BRA-modified asphalt mixture under the low-temperature region. The S-N fatigue equation with the stress ratio related to loading rates was proposed to characterize the fatigue property of asphalt mixtures and reveal the different effects of loading frequency and materials on the fatigue property of asphalt mixtures. The tests results demonstrated that the SBR-BRA-modified asphalt has an equal road performance to SBS-modified asphalt. Analyzed by the S-N fatigue equation with the stress ratio related to loading rates, the fatigue test results under different loading frequencies could be fitted to a fatigue curve, and the fatigue curves of different asphalt mixtures exist at an angle and intersect at point (1, 1). (C) 2020 American Society of Civil Engineers.