Safe use of Electric Arc Furnace Dust (EAFD) as secondary raw material in self-compacting mortars production

Abstract

This research contributes to the development of the Circular Economy concept by managing waste through its use as a construction material. A novel process in which two samples of industrial waste Electric Arc Furnace Dust (EAFD) collected from two different steelwork plants are used as secondary raw material (SRM) in the production of self-compacting mortars is proposed. At a previous stage, a characterisation of mortar material components was carried out. Then, self-compacting mortars with replacement ratios of 25%, 50% and 100% of siliceous filler with EAFD were designed. The feasibility of EAFD use was analysed by means of the study of mechanical strength, mineralogical, capillary properties and leaching behaviour in monolithic and granular state. The environmental classification of mortars, according to their leaching behaviour, was carried out in accordance with European Directive 2003/33/EC (2003). EAFD incorporation modified the self-compactability and common hydration reactions. Mechanical strength decreased with EAFD incorporation, although the mortar with 25% of replacement with one of the EAFD's showed a negligible loss compared to the self-compacting reference mortar. Water absorption by capillarity increased with EAFD content, consistently with the mortars' mechanical behaviour. The leaching behaviour analysis in a monolithic state revealed that all mortar releases were below the permitted limit. In a granular state, the mortar with the best mechanical behaviour was environmentally safe, leaving all the elements encapsulated by the self-compacting matrix. The results of this study contribute to EAFD management through its valorisation as secondary raw material in the production of self-compacting mortars, addressing an unprecedented line of research.