Effects SiO2/Na2O molar ratio on mechanical properties and the microstructure of nano-SiO2 metakaolin-based geopolymers

The effects of the SiO2/Na2O molar ratio (1.0-2.0) on the properties of nano-SiO2 metakaolin-based geopolymers were studied. The setting time and compressive strength were investigated and mercury intrusion porosimetry (MIP), FTIR and SEM used to study the properties of the geopolymers. It was shown that the compressive strength increased, and that the products of geopolymerisation filled pores, with curing time, causing the microstructure to become dense. A nano-SiO2 metakaolin-based geopolymer sample with a SiO2/Na2O ratio of 1.5 had higher strength, higher density, and lower porosity. Applying nano-SiO2 to a geopolymer enhances the compactness, improves uniformity, and increases strength.