Novel Foam Insulation Material Produced by Calcined Phosphogypsum and ${\mathrm{H}}_2{\mathrm{O}}_2$

A novel foam insulation material was prepared using calcined phosphogypsum (CPG) as the raw material and hydrogen peroxide (${\mathrm{H}}_2{\mathrm{O}}_2$) as a foaming agent. Stable foaming of ${\mathrm{H}}_2{\mathrm{O}}_2$ in a CPG-based suspension was achieved. The effects of ${\mathrm{H}}_2{\mathrm{O}}_2$ on the mechanical properties, thermal conductivity, and pore structure of the CPG-based foam insulation materials were investigated. The results showed that, with increasing ${\mathrm{H}}_2{\mathrm{O}}_2$ content, the expansion volume increased but the growth rate decreased. The total porosity and macroscale porosity ($>100\mathrm{\mu m}$) first increased and then plateaued, while the microscale porosity ($<100\mathrm{\mu m}$) first increased and then decreased before plateauing. When the content of ${\mathrm{H}}_2{\mathrm{O}}_2$ was 4%–5%, CPG-based foam insulation materials with low bulk density ($\le 500\mathrm{kg}/{\mathrm{m}}^3$), low thermal conductivity [$\le 0.13\mathrm{W}/(\mathrm{m}·\mathrm{K})$], and acceptable compressive strength ($\ge 0.24\mathrm{MPa}$) were manufactured; these values are similar to those of other thermal insulation materials, such as cement foam and geopolymer foam in low density ranges.