Synthesis of nano-alumina and their effect on structure, mechanical and thermal properties of geopolymer

Abstract

This paper reports on a study of the effects of nano-alumina on the structural, mechanical and thermal properties of geopolymer matrices. Sample composites were produced by mixing metakaolin, an alkaline solution and nano-alumina (1%, 2% and 3%) with a constant L/S ratio 0.55. The resulting products were investigated by XRD, XRF, FTIR, SEM, MIP, TG/DTA and a compressive strength test. The results showed that the insertion of nano-alumina powder improves geopolymer strength. From FTIR and XRD spectra, we found that the structure and geopolymer gel content were enhanced, especially for the optimized proportion of nano alumina (2%), leading to a more homogenous structure, as shown in SEM images. Thus, the density and water absorption of the nano-alumina geopolymer mixture were improved. The introduction of the nano-alumina also had the effect on the thermal properties of the geopolymers, of increasing the weight loss of the composite.