Improving skid-resistance durability of ultra-thin friction course in asphalt pavements through recycled steel slags as basalt replacements

Abstract

The ultra-thin friction course (UTFC) has emerged as an effective solution for restoring skid-resistance on worn pavements. However, the scarcity and high cost of high-quality basalt aggregates pose challenges for UTFC implementation. This study explores the potential of utilizing recycled steel slags (blast furnace slag (BFS), basic oxygen furnace slag (BOFS), and electric arc furnace slag (EAFS) as alternatives to basalt aggregates in UTFC applications. The durability of skid-resistance and shear strength of these steel slag-UTFCs are investigated, and the chemical and mineral compositions of the steel slags are analyzed to assess their suitability. The findings reveal that EAFS-UTFC exhibits superior surface roughness, enhanced wear resistance, and comparable shear strength to Basalt-UTFC. The dynamic friction coefficient (μ) between EAF-UTFC and rubber at 120 km/h is 1.12 times higher than that of basalt at 0 wear cycles, and this advantage amplifies to 3.11 times higher after 400k wear cycles. However, BFS and BOFS are not suitable for direct use in UTFC, which have lower wear resistances and shear strengths compared to basalt, attributed to their poor bulk stability caused by high levels of free CaO and MgO. Consequently, a significant portion of their surface aggregates are dislodged under repeated wheel loading before sufficient polishing occurs. This study offers insights into sustainable solutions for improving skid-resistance on asphalt pavements.