Effect of elevated hot temperatures on hybrid geopolymer synthesized with a mixture of coal fly and bottom ashes

摘要

We have employed a mixture of coal fly and bottom ashes as a source materials of geopolymer. To investigate the thermal behavior of the hybrid geopolymer subjected to high temperature, we manufactured the geopolymer under NaOH solution by replacing the content of bottom ash from 0, 20, 40, 60, and 80 % in weight of the total ash mixture. The hybrid geopolymer specimen obtained in these way were exposed to 300, 600, and 900 °C. The variations in compressive strength, thermal conductivity and micro-structure over temperature conditions were investigated. Especially, after exposure to 900 °C, we obtained the highest values of compressive strength and thermal conductivity than the other thermal conditions. It has been confirmed that the strength enhancement come from the phases change of amorphous microstructure matrix into crystalline phases such as cristobalite, anorthoclase, and nepheline in the SEM and XRD results.