What is Gypsum
Gypsum is a soft white rock known by mineralogists as hydrous calcium sulfate. The term hydrous indicates that it has some water in it. However, this moisture is chemically combined with the other compounds in the rock so it is not readily present. In order to make it usable for construction, Gypsum is heated to temperatures in excess of 350°F (176.6°C) and crushed into a fine powder. This powder can be mixed with water to make plaster of Paris. Plaster of Paris is a thick viscose material that can be poured into molds of all shapes.
Gypsum use in construction
Gypsum is the primary component of both drywall and plaster. After gypsum is turned into a dry powder, it is mixed with water and other materials and either poured into drywall panels or spread as plaster. Besides drywall gypsum is used in other construction materials such as Portland cement, gypsum block, and exterior glass mat sheathing panels.
Gypsum is also used in quick-setting drywall mud. It is combined with other materials like clay, salts, plasticizers, and starchy glues. Ready mix drywall mud usually is made with limestone and talc rather than gypsum though some ready mix drywall muds may include gypsum