Synthesis of geopolymer binder from the partially de-aluminated metakaolinite by-product resulted from alum industry.

In this study an experimental work has been done to test the feasibility of using partially dealuminated metakaolin (PDK) with metakaolin (MK) in the production of geopolymer binder. The chemical composition and physical properties of de-aluminated metakaolin was tested. For this purpose, metakaolin (MK) was partially substituted with partially de-aluminated metakaolin (PDK) at ratios of 0-60% by weight. The alkaline activator was NaOH. Geopolymer pastes were cured at room temperature. The compressive strength was measured by testing standard cubes at 7 and 28 days. Satisfactory results have been achieved by using 15, 20, 30, 35 wt.% of PDK. Hence it was suggested to use the local metakaolin with added proportions of PDK up to 35% of metakaolin to produce economic geopolymer binder. It is technically feasible, resulting in a sustainable and environmentally friendly source of vitreous material. The effect of PDK on porosity and compressive strength were tested. The internal microstructure, and hydration were investigated by using modern methods such as, Thermo-gravimetric (TGA) and differential thermal analysis (TGA, DTGA), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The findings assure the potentiality for the application of PDK as a siliceous material can be used in manufacturing of geopolymer cement. [ABSTRACT FROM AUTHOR]