Steel slag quality control for road construction aggregates and its environmental impact: Case study of Vietnamese steel industry – Leaching of heavy metals from steel making slag

Abstract Steel slag is an industrial by product of steel manufacturing processes and has been widely used in countries like Japan, United States, and European Union nations. However, the current utilization of steel slag in Vietnam is very low mainly because of lack of quality control of slag treatment and chances for reuse of treated steel slag. This paper presents the current steel slag production status and its potential to use as road construction aggregates in consideration of environmental and quality control issues. The basic oxygen furnace (BOF) and electric arc furnace (EAF) slag samples were collected from the seven large steel making factories of Vietnam and brought back to evaluate leaching amount from the slags. The batch leaching test methods were performed at laboratory using the leaching test of steel slag roadbed material in Japan (JIS K 0058 − 1) and Toxicity Characteristic Leaching Procedure (EPA method 1311) widely adopted in Vietnam. The results show that pH level and parameters such as T-Cr, Ni, Cu, Pb, As, Mn differ from the two test methods. The EPA 1311 seems too harsh to evaluate the environmental impacts because in the operation condition of the road, acidic liquid is absent. It is concluded that JIS test, which uses fresh water with gentle mixing not to degradation in size while leaching, is suitable for the evaluation, for the environmental assessment in service of the slag aggregate for roadbed.