Study on Low-Temperature Performance of Steel Slag Crumb Rubber Modified Asphalt Mixture

ABSTRACT To explore the low-temperature performance of steel slag crumb rubber powder modified asphalt mixtures, the mix ratio was firstly designed, the optimal mix ratio of compounded steel slag mixtures was selected through the gray target decision theory, and three kinds of asphalt mixtures were prepared. Then the low-temperature performance of steel slag crumb rubber modified asphalt mixtures was comprehensively analyzed through the low-temperature crack resistance, low-temperature creep performance, and low-temperature relaxation performance tests of asphalt mixtures by considering different test temperatures and loading conditions. Finally, based on the linear viscoelasticity theory, the low-temperature creep and relaxation properties were analyzed, and numerical analysis was applied to realize the mechanical response analysis of the mutual transformation of creep flexibility and relaxation modulus. The results show that the road performance of asphalt mixture modified with steel slag partially replacing asphalt mixture with basalt aggregate and asphalt binder modified by crumb rubber of 5∼20-mm particle size is optimal. The larger the proportion of steel slag in the asphalt mixture, the better the low-temperature cracking resistance, creep deformation capacity, and relaxation performance of the asphalt mixture, but the maximum bending tensile strength (RB) and the maximum bending tensile strain (ϵB) of the all steel slag asphalt mixture show unstable patterns of change at lower temperatures (≤10°C). The analysis of interfacial damage coefficients revealed that the ambient temperature as well as the content of steel slag in the asphalt mixture affects the apparent morphology of the cracked surface of the asphalt mixture. Lower temperature or larger steel slag content will cause cracking to concentrate in the asphalt mastic. Numerical analysis revealed that the best results were obtained by converting the relaxation modulus with direct tensile creep tests.