Evaluation of skid resistance durability of steel slag asphalt concrete through skeleton structure strength and stability analysis

Steel slag is a sustainable alternative to natural aggregates in high-performance skid-resistant asphalt concrete, but the relationship between texture evolution and internal skeleton stability during field service remains insufficiently understood. To address this issue, this study investigated SMA-13 mixtures containing 0% (SS-0), 45% (SS-1), and 78% (SS-2) steel slag from the perspectives of aggregate durability, skeleton strength, and structural stability. Scanning electron microscopy and the Aggregate Imaging Measurement System were used to characterise aggregate micro-textural durability, while computed tomography and dSPACE-based dynamic monitoring were employed to analyse skeleton contact characteristics, deformation resistance, and energy transmission. Field tests were also conducted at different service periods to evaluate the long-term evolution of skid-resistance performance. The results showed that steel slag, owing to its high angularity, density, and complex pore structure, formed a spatial multi-point load-bearing skeleton and enhanced energy dissipation; the average contact number of SS-2 increased by 21.6%, improving structural stability and delaying macro-texture degradation; and after 17 months of service, the side-force coefficient advantage of SS-2 over SS-0 increased from 43.4% to 47.7%. Finally, these findings provide a practical basis for optimising skid-resistant surface layers in high-grade pavements and promoting sustainable material utilisation.