Synthesis of calcined kaolin-based geopolymer foam: Assessment of mechanical properties, thermal insulation, and elevated temperature stability

Calcined kaolin-based geopolymer foam was prepared, characterized, and evaluated in this paper. The different hydrogen peroxide foaming agent dosages were added to the geopolymer paste at 2.5%, 5%, 7.5%, and 10 wt%. The specimens were cured at temperatures of 40 degrees C, 60 degrees C, and 80 degrees C. The influence of hydrogen peroxide and different curing temperatures on the physical properties, mechanical characteristics, and pore distribution were studied. Correlations between these properties were drawn. The results indicated that geopolymer foam can be synthesized using calcined kaolin with acceptable compressive strength values (2.35-11.23 MPa). The geo-polymer foam had a bulk density of (0.46-1.25 g/cm3), a porosity of 45.2%-87.4%, and thermal conductivity of (0.14-0.33 W/mK). The estimated cost of the geopolymer foam developed in this investigation was 156.12 ($/m3). Compared to common thermophysical materials, the developed geopolymer foam is considered a cost-effective option for insulating construction materials.