Performance assessment of mechanical and durability properties of cupola slag geopolymer concrete with fly and rice husk ashes

Abstract

Research into substituting recycled materials for cement and aggregates can yield beneficial natural resource conservation, waste management, cost savings, and reduced embodied energy in concrete. Hence, this research investigates the potential adoption of coal fly ash (CFA) and rice husk ash (RHA) as geopolymer binders to partially substitute cement in varying proportions up to 25%. However, cupola furnace slag (CFS) was also used as a partial substitute of crushed granite from 0% to 35% in steps of 5% in the production of geopolymer concrete (GPC). The selected geopolymer binders were synthesized using an alkaline solution. Workability, compressive strength, and rapid chloride penetration tests on fresh and hardened normal concrete (NC) as control and GPC containing CFS were evaluated at different water-binder ratios. The findings revealed that integrating 15%CFA, 20%RHA, and 30%CFS with w/b of 0.50 and 0.65 improved the workability by 180% and 105.7%, respectively, but compressive strength is significantly reduced. The findings further showed that combining 75%OPC, 20%CFA, 5%RHA, 100%RS, 20%CFS, and 80%CG results in optimal compressive strength of 19.68 N/mm2 and, 21.49 N/mm2 at 28 days and 56 days with w/b of 0.50, respectively, as contrasted to the lowest possible strength requirement. The Rapid Migration Test (RMT) was used to determine the chloride ions permeability in various concrete mixes. The results show that GPC produced with the combination of 15%CFA, 20%RHA 65%OPC, 30%CFS, and 70%CG with w/b of 0.65 is more durable and has higher chloride ion penetration resistance than most other mix proportions.