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What
is Gypsum Drywall?
A description of gypsum drywall must first begin with a discussion of gypsum itself. Gypsum, a naturally occuring mineral, is composed of calcium sulfate (CaSO4) and water (H2O). Also referred to as hydrous calcium sulfate (CaSO4.2H2O), gypsum is mined from deposits formed by ancient seabeds as a raw material for many different manufacturing, industrial, and agricultural uses. Over 80% of the gypsum mined is used in manufactured products such as drywall. Gypsum possesses many attributes that make it an attractive construction material. Calcined gypsum can be wetted to form a paste that can be directly applied to a structure’s surface or that can be molded into a desired shape; the gypsum hardens upon drying. Gypsum is naturally fire resistant. Gypsum drywall, often referred to as gypsum wallboard or sheet rock, replaced gypsum plaster as the major material used for interior wall surfaces because of its ease of installation. Gypsum drywall consists of approximately 90% gypsum and 10% paper facing and backing. Drywall is manufactured by first calcining the gypsum, a process that heats the mineral to remove part of the water (resulting in CaSO4.1/2H2O). The stucco that is formed is then rehydrated by mixing with water, and the slurry created is spread onto a moving continuous sheet of paper and sandwiched between another layer of paper. This continuous sheet of wallboard is allowed to harden for several minutes, cut into panels and sent to a kiln for final drying. It is trimmed to the dimensions required, bundled, and is then ready for shipment. Drywall comes in many different types and sizes to meet specific construction needs. For more information on gypsum and gypsum drywall products, visit the gypsum association home page or one of the gypsum manufacturing company websites. |
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