Mineralogical composition of EAF slag and stabilised AOD slag aggregates and dimensional stability of slag aggregate concretes

An interesting valorisation way of EAF slag and stabilised AOD slag is their use as aggregates in concrete. Mineralogical studies of these steel slags are therefore necessary. In this study, observations of slag aggregates under UV light are associated with usual mineralogical analyses (XRD, SEM and EDS) to ensure more representative results of the mineralogical variability within slag aggregates. Relationships between aggregate mineral composition and UV fluorescence colours are proposed. Mineralogical studies also show that the stainless steel slag contains low amounts of expansive mineral phases (free CaO, free MgO) that could affect concrete volume stability. To verify this finding, swelling measurements of high strength concretes made of EAF slag and stabilised AOD slag aggregates are carried out. The linear expansion of stainless steel slag concretes is slightly higher than that measured for concretes with silico-calcareous aggregates.