Performance evaluation of using electric arc furnace dust in asphalt binder

Electric arc furnace dust (EAFD) is one of the harmful by-products of steel manufacturing industry which contains elements such as Cr, Pb, Zn, Cu, and Cd. These elements are emitted after charge melting in an electric arc furnace. The results of leaching tests demonstrate that the amount of these elements in EAFD exceeds the established limits. To deal with this problem, EAFD can be used as an alternative material in asphalt mix production which improves fatigue life. A large amount of investments are spent on the road maintenance and a significant portion of these investments is assigned to repair cracks caused by iterative traffic load and freeze-thaw cycles. The potential of asphalt self-healing, the ability of recovering mechanical characteristics, aims in improving fatigue life of asphalt pavement as well as reducing energy consumption and environmental side effects. Mastic asphalt is a material with self-healing capability. This paper proposes an effective and efficient treatment which utilizes EAFD as filler in the asphalt mixture. Accordingly, the performance of the fatigue and self-healing potential in the mastic along with two common fillers including Granite and hydrated lime are compared through a time sweep test with/without rest period using a DSR device. Results show that asphalt mastic containing EAFD filler has much better self-healing and fatigue performance than those containing Granite filler. Consequently, using this filler in asphalt mixture decreases environmental side effects in addition to manufacturing cost reduction and improving economic aspects of asphalt production. Moreover, the environmental aspects of using EAFD in asphalt binder are investigated and the result of leaching test indicates that pavements constructed by EAFD has no threat for ground and surface waters. For monitoring the amount of pollution leaching from asphalt mixture containing EAFD into flowing water, Toxicity Characteristic Leaching Procedure (TCLP) was investigated. TCLP Results showed that the amount of heavy metals for all of these samples are lower than the regulatory levels.