Mechanical Activation of Medium Basicity Steel Slag under Dry Condition for Carbonation Curing

This paper attempts to turn medium basicity basic oxygen furnace (BOF) slags into construction materials by carbonation curing and enhance the reaction rate by utilizing mechanical activation. It was found that BOF slag becomes an aggregated after 30 min of grinding, providing the specific surface area was reduced with prolonged milling. The silicates, hydroxides, sulfates, aluminates and ferrates comprising BOF slag became amorphous after mechanical activation, however, the RO phase was nearly unchanged, and CaO crystalized. Mechanical activation cannot enhance the carbonation conversion of BOF slag after carbonation up to 24 h in duration alone. However, mechanical activation improved the compressive strength of carbonated BOF slag compacts when the water-solid ratio was high. The accelerated hydration reaction forms C-S-H and C-A-S-H, acted as catalysis for the carbonation process. To effectively activate the steel slag for carbonation curing at ambient temperature, this method that could enhance the rate of carbonate precipitation and is preferred to simply grinding.