Abstract The aim of this work is to comprehensively investigate the possibility of partially substituting natural aggregates with Black/Oxidizing Electric Arc Furnace (EAF) slag in concrete production. Five recycled and one traditional mixes were produced to identify a convenient substitution ratio for the concrete. Main physical and mechanical properties of concrete containing EAF slag as aggregate according to Fuller’s grading curve were experimentally investigated. Chemical and durability tests were performed to study the microstructure and analyse the behaviour of the conglomerate exposed to detrimental agents. Results showed that high substitution ratios of coarse natural aggregates are possible without decreasing mechanical properties of concrete. Conversely, replacement of fine natural aggregates with recycled ones seems feasible at lower substitution ratios only. Presence of calcium and magnesium oxides in the slag does not seem to represent a limit for the durability of concrete, due to their stabilization in crystalline lattice.