Effect of Kaolinite Mass Ratio on Compressive Strength of Kaolinite-Calcite Based Geopolymer

Abstract

This study focuses on the preparation of geopolymers using various proportions of kaolinite and calcite mixture, and the effects of kaolinite mass ratio to calcite on compressive strength of kaolinite/calcite-based geopolymer. Several geopolymer samples were formed using pure kaolinite, pure calcite, and various mass ratio of kaolinite to calcite to examine properties of the geopolymers. The impact of NaOH concentration on the compressive strength of the geopolymers was also examined. The results of the laboratory analyses indicate that the compressive strength of geopolymers did not increase steadily with increasing concentration of NaOH. The optimum workability of geopolymers was obtained at 10 M NaOH and 30 % kaolinite content in the mixture. Several sensitivity experiments were carried out using the parameters at cure temperatures of 22, 45, 65 and 85 o C. The best compressive strength of 12.68 MPa was obtained on the 28th day of curing process at 85 o C. The structural evolution of the geopolymers prepared was investigated using FTIR spectroscopy. They were also characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM).