Effect of steel slag contents on road performance of rubber-modified permeable asphalt mixtures

Based on laboratory test results, this study provides a comprehensive evaluation of the mechanical properties, durability, microstructural characteristics, and functional properties of steel slag rubber permeable asphalt mixtures with different steel slag contents, leading to the following conclusions: Incorporating steel slag into the mixture effectively enhances its skeleton strength and high-temperature stability. When the steel slag content reaches 60%, the dynamic stability (DS) of the mixture increases to 7,852 cycles/mm. Although the low-temperature failure strain of the steel slag mixture decreases to 2,820 με, the addition of rubber modifiers ensures that the mixture meets winter road performance requirements. Due to the alkalinity of steel slag which enhances bonding between aggregates and asphalt, the soaked residual stability of the mixture increases to a maximum of 91.2%, and the freeze-thaw splitting strength ratio peaks at 88.6% when the steel slag content is 50%. The addition of steel slag effectively regulates the internal void structure of the mixture, creating more interconnected voids. At a 60% steel slag content, the water permeability coefficient of the mixture significantly increases to 5,581 mL/min. Although the porous surface structure of steel slag causes aggregates to adhere to a thicker asphalt film, resulting in an initial pendulum value stabilizing around 62, the texture depth of the mixture significantly increases to 2.48, which benefits road traffic safety. The optimal steel slag incorporation ratio is ultimately determined to be 50%–60%. This study concludes that steel slag rubber permeable asphalt mixture is a highly promising sustainable material that not only alleviates the shortage of high-quality natural aggregates but also enables high-value utilization of industrial solid waste.