Utilization of Alumina Waste and Silica Waste for Geopolymer Production

This research studies the utilization of alumina waste and silica waste for geopolymer production. Alumina waste was obtained from aluminium thermal metallurgy industry, silica waste was obtained from silicone recycle industry in Thailand. This present study aimed at investigating the basic physical and chemical properties of waste materials and also the optimal proportion in geopolymer production. The results revealed that alumina waste contained 48 percent of aluminium oxide, 4.18 percent of Silicon dioxide and average particle size is 36 micrometers. Silica waste contained 71.3 percent of Silicon dioxide and average particle size is 49 micrometers. The leaching tests of heavy metals also indicated that the level of all heavy metals concentration were over the standard set by the Ministry of Industry, Thailand which means both alumina and silica waste were considering as hazardous waste. In geopolymer production, the mortar was cast in 5x5x5 centimeters cubic shape for both methods with cured temperature at 60 degree celsius. Compressive strength was tested at 1, 7, 14 and 28 days. The results revealed that the best SiO2:Al2O3 ratio must be 3:1 mixed by alumina waste 46 g. and silica waste 24 g. with 10 ml of sodium hydroxide and 20 ml of sodium silicate. This proportion gain the highest compressive strength for 262.8 kg/cm2 at 28 days of curing which over the standard for hollow load-bearing concrete masonry units (TIS57-2530) and costs 4.03 THB/mortar. The leaching tests were estimated again after the production of geopolymer. The results indicated that the concentration of all heavy metals was within the standard set by the Ministry of Industry, Thailand. Therefore the production of geopolymer mortar from alumina waste and silica waste were not considering as hazardous waste.