Characterization and activation of Basic Oxygen Furnace slag

BOF slags are by-products of steel conversion. They are a valuable mineral resource for the construction but have chemical properties that directly control their stability or any hydraulic activity. This paper provides a complete characterization and quantification of BOF slag phases in order to better understand their potential hydraulic activity. The acceleration of the hydration by chemical admixtures is also presented. The BOF slag variability is investigated on several samples with different origins and ages.BOF slag with different origins mainly contain 38–52% C2S, 20–30% C2F, 1–7% Ca(OH)2, 11–13% Fe1−xO, 2–8% CaO. Calcium silicate is present in β-C2S form which is the active polymorph present in clinker. BOF slags have poor hydraulic activity at early ages which can be enhanced by calcium chloride addition.

► We propose a comprehensive methodology for Basic Oxygen Furnace slag characterization using complementary techniques.
► We study the chemical activation of BOF slag hydrated pastes with different chemical admixtures.
► BOF slag mainly contain C2S, C2F, Ca(OH)2, Fe1−xO, CaO, and with fewer proportions CaCO3, SiO2 and MgO.
► CaCl2 significantly increases the early age resistance of BOF slag.