Substituting brick aggregate with induction furnace slag for sustainable concrete

Due to the scarcity of natural sources of stone in Bangladesh, crushed brick chips are predominantly used as coarse aggregate in concrete. The production process of bricks is not environment-friendly. In this study, the potential of waste induction furnace slag (IFS) as a replacement of brick aggregate was investigated. The effects of replacing crushed brick aggregate by IFS aggregate on properties of concrete were studied, for varying mix design parameters including W/C ratio (0.45 and 0.50), cement content (340, 375, and 400 kg/m3), and fine aggregate to total aggregate volume ratio (0.40, 0.44, and 0.48). Concrete mechanical properties were assessed using conventional means and ultrasonic pulse velocity through concrete was measured. Aggregate-matrix interfaces were examined using a scanning electron microscope (SEM). Results indicate that any replacement of brick aggregate by IFS enhances concrete mechanical performance and workability compared to 100% brick aggregate concrete, while the best mechanical performance is achieved at 50% replacement. Relationships between different hardened-state properties of concrete have been proposed for 0%, 50%, and 100% replacements. A 35% reduction in the CO2 footprint of concrete can be achieved by fully replacing brick aggregate with IFS, with at least a 30% reduction in cost.