Synthesis and attributes of nano-SiO2 local metakaolin based-geopolymer

Abstract

The present experimental study treats the synthesis of local meta-kaolin based geopolymer with and without incorporation of nano-silica. The physical behavior was examined by compressive strength, water absorption, density and ultra-pulse velocity measurements. The XRF, XRD and FTIR were used to investigate the chemical composition and structural properties of the synthesized geopolymers, while the microstructural characteristics were studied by SEM, optical transmittance and MIP analysis. The XRD and FTIR spectra showed that the addition of 5% nano-silica increased the amorphous structure and improved the nucleation site of geopolymer gel. Moreover, the addition of nano-silica densified the geopolymer matrix as shown by SEM and MIP analysis and confirmed by the trends of the optical transmission, water absorption and density values. Furthermore, the increase in the compressive strength was noticed with 5% addition of nano-silica at 20 °C and 80 °C. However, the increase in the compressive strength at 28 days for the nano-silica geopolymer was more significant at 20 °C as compared to the 80 °C. In addition, TG analysis revealed that the nano-silica geopolymers have shown greater weight loss compared to the control geopolymer. Finally, the experimental results have shown the possibility of using the local clay for the synthesis of alkali activated geopolymer; however, the detailed eco-environmental considerations are necessary for its industrial applicability.