Synthetic aluminosilicates for geopolymer production

Abstract

The use of geopolymer has been studied as a potential substitute for Portland cement due to lower CO2 emission and improvements on structural properties. Some of the major raw materials used in the manufacture of the geopolymer are: steel slag, fly ash and metakaolinite. Due to the impurities contained in these raw materials, the present study uses high purity synthetic aluminosilicates made from the sol gel process for production of geopolymers. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR). The results showed that the synthetic aluminosilicates have similar behavior to metakaolinite (reference). It was found that the coordination of Al in the synthetic aluminosilicate changed from VI to IV and V from 300 °C, with the highest intensity at 900 °C. Temperature at which the highest mechanical strength of the geopolymer was also observed.