Evaluation on Mixing Parameter of S/L and Na2SiO3/NaOH Ratios Towards Fly Ash Geopolymers

Effect of solid-to-liquid ratios (S/L) and sodium silicate-to-sodium hydroxide (Na2SiO3/NaOH) were studied in this paper. Fly ash was used as the raw material for making the geopolymers paste. The geopolymers were cured at room temperature (24 hours) and 60 degrees C (24 hours), respectively. Strength development, total porosity and microstructural analysis were investigated to reveal the results of this study. Furthermore, SEM micrographs disclose that the fly ash dissolve more readily in the alkaline activator. The correlation between microstructures of the both ratios and their strength development are discussed. The microstructure shows that the matrix denser compared to other ratios. It is revealed that solid-to-liquid (S/L) and sodium silicate-to-sodium hydroxide (Na2SiO3/NaOH) ratios of 2.0 and 2.5 results in the decreases in porosity of the fly ash geopolymers while the compressive strength achieves the highest value.