Electric arc furnace slag and its use in hydraulic concrete

•EAF slag is a rocky material of use in construction and civil engineering.•EAF slag shows some chemical changes and slight expansiveness over time.•Collaboration producers-consumers of EAF slag is essential to efficient re-use.•EAF slag is a suitable aggregate for hydraulic cement concrete.•EAF slag forms a particular type of microstructure in the interfacial transition zone.

Electric arc furnace oxidizing slag (EAFS) is a by-product of the steelmaking industry, generated after the melting and the preliminary acid refining of liquid steel. It is a stony material that is easy to crush for use as aggregate in concrete mixes.This study examines the long-term aging reactions of EAFS and its volumetric stability, to gain further knowledge of this by-product, its behaviour as a construction material, and its inherent risk of swelling. Additionally, the good compressive strength of hydraulic mixes that incorporate this slag can be analyzed and explained on the basis of its steady and expansive compounds and its chemical evolution over time in the interfacial transition zone (ITZ); the appearance of calcium carbonate enhances the cohesiveness, stiffness and strength of this zone and, as a consequence, of the hydraulic concrete.