Electric Arc Furnace Slag as Coarse Recycled Aggregate for Concrete Production

Electric arc furnace (EAF) slag is a by-product of steel production in electric arc furnaces. Several studies have tried to demonstrate its suitability in civil engineering application, such as in bituminous mixtures and cement based materials, due to its good physical, chemical and mineralogical properties. Particularly the re-use as coarse aggregate for concrete production has been shown to be a promising valorisation, when physical and chemical stability is guaranteed. Additionally, EAF slag’s high mechanical strength makes it suitable for high-performance concrete production. In this work three EAF concretes, with various cement content and also with silica fume addition, were compared with a reference concrete, to identify a convenient mix design to reach a concrete strength class between C50/60 and C60/75. Mechanical strength was evaluated analysing compressive and tensile strength, and elastic modulus. A complementary microstructural analysis was performed after the failure of the specimens, with the aim of analysing the morphology of the interfacial transition zone. Results indicate that the use of EAF slag in concrete allows reaching higher compressive strength than with coarse natural aggregates. EAF slag application in structural concrete promotes also the reduction of cement content in the mix to reach the same strength class.