Foamed gypsum composite with heat-resistant admixture under high temperature: Mechanical, thermal and deformation performances

Abstract This paper presents an experimental study to investigate the mechanical, thermal and deformation properties of foamed gypsum exposed to high temperature. The pure gypsum, ordinary foamed gypsum with different densities (800 kg/m3, 650 kg/m3), foamed gypsum with glass fiber or with expanded vermiculite were tested in the temperature range of 25 °C-800 °C. The results show that the low density ordinary foamed gypsum generates less thermal cracks than the high density gypsum at elevated temperature. Furthermore, the incorporation of the glass fiber can increase the thermal shrinkage and cracks of the gypsum composite after the melting of glass fiber, while the expanded vermiculite can significantly benefit in reducing the loss of mechanical strength, shrinkage and cracks of gypsum composite at high temperature. Finally, the mechanisms of substantial changes of the mechanical strength related to physical, chemical and microstructural transformations were discussed.