Influence of the type of foam agent on microstructure and properties of gypsum stone

The article investigates the microstructure and properties of gypsum stone (GS) when used with synthetic (SFA) and protein (PFA) foaming agents The authors found out that the microstructure of GS with SFA is represented by coarse particle crystals of calcium sulfate dihydrate of plate-acicular morphology with a volume of mesopores with a diameter of 3-33 nm up to 43×10-3 cm3/g and macropores with a diameter of 60-130 nm up to 30×10-3 cm3/g. The microstructure of GS with PFA differs in the content of finely dispersed, close-packed CaSO4×2H2O crystals of a prismatic habit with a mesopore volume of up to 57×10-3 cm3/g and macropores of up to 19×10-3 cm3/g. It was established that synthetic foaming agent enables to reduce average density of gypsum stone to 430 kg/m3, and the thermal conductivity to 0,14 W/(m×°C). Protein foaming agent results in compaction and hardening of the GS.