Accelerated carbonation of steel slag for enhanced carbon capture and utilization as aggregate in alkali-activated materials
Eduardo Antonio Pinto Dias, Adriano G. S. Azevedo, Holmer Savastano, Paulo Henrique Ribeiro Borges
Abstract
Accelerated carbonation of Ca- and Mg-rich solid wastes is a transformative method to control CO 2 emissions and eliminate waste and by-products, such as basic oxygen furnace slag (BOFS). This technology is considered a feasible method to limit volumetric instability and bring economic and environmental value to BOFS aggregates. This study evaluated the effect of pre-treatment carbonation conditions (temperature, moisture conditions and CO 2 pressure) of BOFS subsequently used as aggregates for alkali-activated mortars. The mechanical, physical and microstructural properties of alkali-activated mortars containing 100 % BOFS aggregates carbonated from different conditions were assessed. The results showed that the carbonation process of BOFS aggregates is mainly influenced by its moist conditions, followed by the CO 2 pressure. In general, carbonated BOFS aggregates present after the pre-treatment a rougher surface characterized by a higher specific surface area, which improves the bonding between the matrix and aggregate, with consequent improvements in the mechanical properties of the alkali-activated mortars.