Exploring skid resistance over time: Steel slag as a pavement aggregate—comparative study and morphological analysis

Abstract

Steel slag has been investigated as a potential aggregate for pavement-wearing courses in road engineering. The volume stability, resistance to high and low temperatures, and water stability for asphalt mixtures containing steel slag have been widely studied. As for the skid resistance, previous studies have primarily focused on the initial performance. The relationship between the steel slag's appearance morphology and skid resistance during the wearing process remains to be further explored. It is essential to undertake a comparative study on the long-term skid resistance of steel slag and conventional aggregates to address the differences. This research picked two steel slags and two types of conventional aggregates (granite and limestone) as research samples. The chosen aggregate samples underwent various degrees of wear treatment with the Los Angeles abrasion machine, and their angularity was examined utilizing an aggregate image measurement system (AIMS). Based on the polishing pre-treatment, the micro-texture of the aggregates was observed with the assistance of a laser confocal microscope, and its correlation with skid resistance was determined. British pendulum number (BPN) tests were also conducted and analyzed at various polishing durations. The results show that steel slag has a low abrasion rate and higher initial angularity and abrasion resistance compared to natural stones. The micro-texture analysis demonstrates that steel slags have a coarser roughness, more contact points, and more durable abrasion resistance. Additionally, the fluctuations in BPN further prove that steel slag has superior initial and sustained skid resistance. Overall, steel slag can be a promising alternative for pavement-wearing course aggregate due to its superior long-term skid resistance.