Preparation of calcium silicate board from tobermorite-rich residue for energy conservation in buildings

Abstract

The tobermorite-rich residue was derived from coal fly ash after alumina extraction via a hydrothermal process, which was used to prepare calcium silicate board for energy conservation in buildings. By employing a formulation comprising 94 wt% tobermorite-rich residue and 6 wt% pulp, the resultant calcium silicate board exhibited notable characteristics when subjected to a compression pressure of 20 MPa, including a bending strength of 6.75 MPa, a bulk density of 0.63 g/cm3, and a thermal conductivity of 0.14 W/(m·K). Tobermorite within the residue predominantly exhibited a fibrous morphology and formed porous aggregations, which proved advantageous in preparing calcium silicate board of high bending strength and good thermal insulation performance. Furthermore, the tobermorite retained its fibrous morphology even at elevated temperatures exceeding 650 °C, this thermal stability conferred excellent fire resistance performance upon the resulting calcium silicate board. Conclusively, the calcium silicate board prepared from tobermorite-rich residue demonstrated superior performances like good thermal insulation, exceptional fire resistance, light weight and high strength, etc., which would show great potential for use in buildings.