Ceramics-Silikáty 58 (3) 215-222 (2014)

Role of the synthesis method on the microstructure and mechanical properties of metakaolin-based potassium geopolymers

The synthesis method used has an important effect on the development of the compressive strength of a material. This work aims to research the effect of synthesis temperature (30°C and 70°C), curing condition (dried and sealed curing) and alkaline solutions (S_c commercial alkaline solution and S_l laboratory alkaline solution) on the development of compressive strength. The microstructure of these geopolymers was characterized using thermal analysis as well as porosity and microscopic observations, and the results were discussed. The total porosity was found to play a negative role on the compressive strength. Synthesis at a lower temperature demonstrated a better compressive strength due to the lower porosity and smaller pore sizes. The S_l geopolymers showed a better compressive strength than the S_c geopolymers due to their lower porosity. It was also found that the reaction was hindered when the samples were cured under a dried curing condition.

Keywords: Temperature effect, Curing condition, Compressive strength, Alkaline solution, Microstructure, Synthesis methodology