Research on low-temperature performance of steel slag/polyester fiber permeable asphalt mixture

In order to improve the low-temperature crack resistance of the permeable asphalt mixture, five steel slags with equal volumes of substitution rates (0%, 25%, 50%, 75%, 100%) were used to replace the limestone coarse aggregate above 2.36 mm. At the same time, six types of polyester fibers (0%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50% by the weight of the mixture) were selected to prepare permeable asphalt mixture samples. The ultrasonic non-destructive testing test, semi-circular bending (SCB) test and scanning electron microscope (SEM) test were carried out to study the cracking performance of steel slag/polyester fiber asphalt mixture at low temperature (0 °C, −10 °C, −20 °C). Ultrasonic non-destructive testing shows that by appropriately increasing the number of compactions (85 times), the aggregate embedding effect of G50X0.45 permeable asphalt mixture can be increased, and the compactness of the mixture can be improved. SCB test results suggest that the critical load for cracking of steel slag/polyester fiber permeable asphalt mixture first increased and then decreased with the decrease of temperature, reaching the maximum at −10 °C; At 50% steel slag replacement rate and 0.45% polyester fiber content, the ultimate tensile stress and ultimate tensile strain of the asphalt mixture were the largest, showing the optimal low-temperature crack resistance. The SEM test results indicate that adding steel slag enhances the embedding and squeezing effect between the internal aggregates of the mixture, the physical and chemical adsorption between the steel slag and the asphalt forms an asphalt orientation layer, which enhances the cohesion of the mixture. The incorporation of polyester fiber weaves a three-dimensional structure network inside the mixture, which firmly locks the coarse and fine aggregates together, greatly improves the density of the mixture, reduces the freeness of the asphalt, and thus improves low-temperature crack resistance of steel slag/polyester fiber asphalt mixture.