Effect of TC–TTS‐Modified Steel Slag Powder on Pavement Performance of Asphalt Mastic and Asphalt Mixture

To verify the feasibility of replacing mineral filler with steel slag powder in asphalt mixtures, surface modification was performed on two steel slag powders from different sources (Liansteel powder and Xiangsteel powder) using a TC–TTS titanate coupling agent. The physicochemical properties and micromorphology of the modified steel slag powders were systematically studied. The physical, rheological, chemical, and thermal properties of the modified steel slag powder asphalt mastics at filler–bitumen ratios of 0.6, 0.8, and 1.0 were analyzed, and the pavement performance of the modified steel slag powder asphalt mixtures was verified. The results indicate that TC–TTS modification significantly reduces the plasticity index of steel slag powder (by 35%–42%), thereby meeting the specification requirements. The crack resistance of the modified steel slag powder asphalt mastic is more than 20% higher than that of the mineral filler mastic, and its glass transition temperature decreases by 1.3°C–2.7°C. Chemisorption occurs between the modified steel slag powder and asphalt, forming a Si–O–Si network structure that markedly enhances the low‐temperature toughness of the mastic. The steel slag powder asphalt mixture achieves an improvement in low‐temperature crack resistance exceeding 10% and exhibits superior low‐temperature aging resistance. This study provides a theoretical basis and technical support for the high‐value utilization of steel slag powder in asphalt pavement engineering.