The Utilization of Concrete Residue with Electric Arc Furnace Slag in the Production of Geopolymer Bricks

The purpose of this study was to investigate the ratio of concrete residue (CR) and electric arc furnace slag (EAF) for the production of facing brick according to Thai Industrial Standard (TIS) 168-2546. These two industrial wastes contain high alumina and silica for the production of geopolymer bricks. In this research, CR and EAF were collected and homogenously mixed at the following CR to EAF ratios: 100: 0, 90: 10, 80: 20, 70: 30, and 60: 40, with sodium hydroxide (10M NaOH) and sodium silicate (Na2SiO3) solutions as catalysts. The ratio of Na2SiO3 to 10M NaOH was 2.5. The mixtures were poured in molds (5 cm x 5 cm x 5 cm) and cured in plastic film at room temperature for 28 days. Then the mechanical and chemical properties of the brick specimens were analyzed, including dimensions and tolerances, wryness, deviation from right angles, water absorption, compressive strength, stains, holes, rails, and cracks, according to TIS 168-2546. The results showed that the optimum CR to EAF ratio of geopolymer bricks that was compliant to the TIS 168-2546 standard was 80: 20, which had the highest compressive strength value (17.04 MPa) and the lowest water absorption (0.69%). Therefore, CR and EAF can be used as raw materials for facing bricks production.