Investigation on the impact of different activator to solid ratio on properties and micro-structure of metakaolin geopolymer

The aim of this paper is to investigate the effects of different activator -to-solid ratios on water consumption, setting time, fluidity, adhesion properties, bulk density and mechanical properties at standard consistency. The microstructural mechanisms of metakaolin geopolymer were also investigated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The experimental results showed that for the different activator to solid ratios and mix designs used in this paper, higher ratios enhanced the fluidity, consistency, and setting time. Besides, the standard consistency water consumption of the metakaolin polymer mortar was reduced. SEM and FT-IR tests revealed macroscopic phenomena where the polyaluminum silicate structure improved with increasing activator -to-solids ratios. Excessive sodium silicate reduced strength, thus affecting mechanical properties.