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Gypsum belongs to the monoclinic crystal material, with a high degree of cleavage, and easy to crack into thin slices. Heating the gypsum to 100-200°C will lose part of the crystal water and obtain hemihydrate gypsum. It is an air-hardening cementitious material with two forms of α and β, both of which are rhombic crystals, but their physical properties are different. α-type hemihydrate gypsum has good crystallinity and firmness; β-type hemihydrate gypsum is a flaky and cracked crystal with very fine crystals, and its specific surface area is much larger than α-type hemihydrate gypsum.

When producing gypsum products, α-type hemihydrated gypsum requires less water than β-type, and the products have higher compactness and strength. Usually, it is α-type hemihydrate gypsum, also called high-strength gypsum, which is steamed in an autoclave in a saturated steam medium; it is β-type hemihydrate gypsum, which is also called building plaster. Industrial by-product chemical gypsum has the same properties as natural gypsum and does not require excessive processing. The slurry mixed with hemihydrate gypsum and water re-forms dihydrate gypsum, which quickly condenses and hardens during the drying process to gain strength, but it softens when exposed to water.

Gypsum is the main raw material for the production of gypsum cementitious materials and gypsum building products, and it is also a retarder for Portland cement. After the gypsum is calcined at 600-800°C, a small amount of lime and other catalysts are added to grind together to obtain anhydrite binder (also called King's binder); calcined at 900-1000°C and ground to obtain high-temperature calcined gypsum . Products made from these two types of gypsum have higher strength than building gypsum products, and anhydrite binder has better thermal insulation, and high-temperature calcined gypsum has better wear resistance and water resistance.