The potential of industrial waste: Electric arc furnace slag (EAF) as recycled road construction materials

Abstract

This research aims to obtain insights into the expansion catalyzation mechanisms of (i) water at room temperature and 80 °C, and (ii) acetic acid on the Electric Arc Furnace (EAF) slag before use as aggregates in road materials. The volume expansions of the EAF slag after soaking under various conditions were investigated. The results indicated that the soaking of EAF slag in 2 wt% acetic acid was the most effective technique to minimize the volume expansion before usage as construction materials when compared to the soaking of EAF slag in water at high temperature of 80 °C. The lowest value of 0.12 % was found for the specimens soaked in the 2 wt% acetic acid for five days. The specimens soaked in the 2 wt% acetic acid for soaking times < 5 days met the criteria for safe use as aggregates in base materials according to the local road authority. The soaking of EAF slag in 2 wt% acetic acid has shown dissolved Calcium (Ca) from unstable mineralogy phases forming calcium acetate and calcite. The California bearing ratio (CBR) values of EAF slag soaked in 2 wt% of acetic acid, for all soaking periods, were slightly lower than those of the specimens soaked in water due to the lower surface particle strength caused by the acid corrosion. The CBR values were however found to meet the minimum requirement corresponding to the Thailand’s Department of Highways (DH-S210/2547). Toxicity characteristic leaching procedure analysis (TCLP) of EAF slag has shown that leachates contained heavy and hazardous elements within the permissible limits according to USEPA. The outcome of this research will promote the usage of EAF slag treated with acetic acid in sustainable road applications.