Development of Room Temperature Curing Geopolymer from Calcined Water-Treatment-Sludge and Rice Husk Ash

Geopolymer is an environmental friendly material, and is expected to use as the cement replacement materials. Because, the geopolymer production does not emit carbon dioxide gas, and is a low energy consuming process. Moreover, geopolymer can be synthesized from variety kinds of waste materials. The present work, the room temperature curing geopolymer has been developed by using the calcined water-treatment-sludge (WTS) and the rice husk ash (RHA) as the precursors. Mixture of sodium hydroxide solution and sodium silicate solution was used as an alkali activator solution. The results show that the RHA promotes strength of the WTS-geopolymer. By adding RHA 30 wt%, strength of geopolymer is close to the minimum required strength of the ordinary Portland cement (OPC). In addition, density of WTS-RHA geopolymer is 3 times lower than that of the OPC. Knowledge in the present work opens an opportunity to apply geopolymer for using in variety kinds of engineering applications, especially the lightweight construction materials.