Mechanical Response of Geopolymer Foams to Heating-Managing Coal Gangue in Fire-Resistant Materials Technology

Two geopolymer foams were prepared from a thermally activated coal gangue containing kaolinite. As the foaming agent, aluminium powder and 36% hydrogen peroxide were used to obtain two levels of porosity. The materials' high temperature performances were investigated: tensile and compressive strength evolution with temperature. This study shows that the mechanical performances of developed geopolymer foams are similar to foam concrete of the same apparent density. The geopolymer foams from coal gangue present stable mechanical performances up to 600 degrees C. When the glass transition temperature is achieved, sintering occurs and mechanical performance increases. SEM observations confirm the glass transition and densification of the matrix at temperatures above 800 degrees C. Moreover, the XRD measurements revealed a high amount of mullite that forms at 1000 degrees C that explained the observed strength increase. The synthesis of good-quality geopolymer foams from coal gangue and its application as a thermal barrier is feasible. The constant level of porosity and its stable character in the range of temperatures 20-1000 degrees C ensures stable thermal insulation parameters with increasing temperature, which is extremely important for fire protection.

Automated summary

This study investigates the high temperature performance of geopolymer foams prepared from thermally activated coal gangue. The foams exhibit stable mechanical performance up to 600°C and demonstrate sintering and increased strength at higher temperatures. Mullite formation is observed at 1000°C, explaining the observed strength increase. The research shows that geopolymer foams from coal gangue can be used as a thermal barrier with stable insulation parameters up to 1000°C.