Preparation and fireproofing performance of the wollastonite-metakaolin-based geopolymer foams

This paper aims to investigate the physical properties and fire resistance of wollastonite-metakaolin-based geopolymer foams (WMGFs). Both compressive and flexure strengths of WMGFs are significantly improved since wollastonite fibers possess inherent stiffness and provide effective crack control. Meanwhile, wollastonite addition promotes viscosity of geopolymer slurry to some extent and then determines pores formation in foaming process, which is also crucial for mechanical strength development. The thermal conductivity of the specimens rises triflingly with elevated wollastonite addition corresponding to slightly decrease in porosity. Owing to the steady skeleton structure of WMGFs, the highest reverse-side temperature of sliced blocks is merely 202.7 degrees C after exposed to fire for 3 h, showing that the reduction in thermal conductivity has no negative impact on fire resistance of specimens. Physicochemical stability of wollastonite under high temperature and alkaline environment is confirmed to be vital for sustaining integrated porous skeleton structure of geopolymer foams. Therefore, geopolymer foams reinforced by wollastonite possess extraordinary mechanical strength and fire resistance, revealing strong possibility for fire protection.