Preparation of multifunctional gypsum composite with compound foaming process

In this paper, a compound foaming process (a combination of physical foaming and chemical foaming) was used to prepare lightweight flue gas desulfurization (FGD) gypsum composites (FGD gypsum/white cement ratio is 7:3, by mass) to enhance sound absorption and thermal insulation. The effect of H2O2 (chemical foaming agent, 0.0 wt%, 1.0 wt%, 2.0 wt%, 3.0 wt%) on their sound absorption, thermal insulation properties, and pore structure was evaluated. The relationship between pore structure parameters and performance was investigated based on a Pearson correlation analysis. According to the X-ray computed tomography (X-CT), the compound foaming process (H2O2, 2.0 wt%) can successfully increase the coordination number of pores by 14.0% and raise open porosity by 6.4% when compared to the physical foaming technique (H2O2, 0.0 wt%). The compound foaming process increased the noise reduction coefficient (NRC) of the material by 28.57% and decreased the thermal conductivity by 7.68%.