Yuquan Plaster Raw石膏Powder, Building石膏Powder, Supply, Customized, Direct Sale

Plaster of Paris generally appears white or colorless transparent. When impurities are present, it can take on shades of gray-brown, yellow, etc. Its specific gravity ranges between 2.31 to 2.33, and its Mohs hardness is 1.5 to 2. Its solubility in water is relatively low; at 20°C, the solubility of the dihydrate石膏, when converted to CaO, is 2.05 grams per liter. After hardening, plaster has a high porosity, up to 50% to 60%, resulting in low density and strength. Building plaster has a strong hygroscopic nature; upon absorbing moisture, the bond between crystals weakens, significantly reducing its strength. When it encounters water, the crystals dissolve, causing damage. Freezing after absorbing water makes it more prone to cracking. Therefore, the water resistance and frost resistance of pure building plaster are poor. Unlike lime and cement, plaster does not shrink upon setting; instead, it slightly expands (about 1%) and does not crack during hardening. This allows plaster to be cast into components with precise dimensions and smooth, fine surfaces. Plaster is a poor conductor of heat, with a thermal conductivity of 0.259 kcal/m·°C·hr between 16°C and 46°C. When exposed to fire, the heat is absorbed due to the evaporation of crystalline water in the dihydrate石膏, and the resulting anhydrous material is an excellent thermal insulator, making plaster fire-resistant.