Geopolymerization of glass- and silicate-containing heated clay

Abstract

The microstructures of cured alkali-activated glass-modified heated clay and sodium silicate-containing heated clay were investigated by using X-ray diffraction, Fourier transform infrared spectroscopy, thermal analysis and scanning electron microscope. Moreover, the effects of the SiO2/Na2O ratio, ageing time and curing temperature and their mutual interactions on bending strength and water absorption of the cured alkali-activated materials were assessed by using the response surface methodology (RSM). It was found that the cured materials were composed of gels, neoformed crystalline phases (Na-chabazite, sodium carbonate) together with starting constituents (illite, quartz, metakaolinite, glass). The zeolite/gel essentially neoformed from metakaolinite derivatives. Sodium carbonate was the product of samples carbonation. A part of the gel formed from waste glass and sodium silicate derivatives respectively. The RSM results showed that the weights of the effects of the experimental factors on the measured properties of the materials obtained were well predicted by using polynomial models, and the SiO2/Na2O ratio was the most influencing factor. The effects of the factors studied were discussed in relation to the microstructure characterization. Also, the results showed that cured alkali activated glass-amended heated clay could be suitable for bricks manufacturing.