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Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ·2H 2 O. [4] It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk.
Gypsum is a mineral and non-combustible building material (a class A1 building material in accordance with the German DIN 4102, the European EN 13501 or the British BS 476 or the American ASTM E119) consisting of calcium sulphate dihydrate (CaSO 4 ·2H 2 O). Because of the stored water, gypsum is a good fire protection building material. In the ...
The development of plasterboard (a sandwich of gypsum plaster between two sheets of paper) dates back to the late nineteenth century in the US. The first patent was granted in 1894 but it was not until an American, Frank Culver, persuaded his new employer, Thomas McGhie and Sons, to buy a plasterboard plant from the US that this new product was introduced to Britain.
Various sized cuts of 1 ⁄ 2 in (13 mm) drywall with tools for maintenance and installation . Drywall (also called plasterboard, dry lining, [1] wallboard, sheet rock, gib board, gypsum board, buster board, turtles board, slap board, custard board, gypsum panel and gyprock) is a panel made of calcium sulfate dihydrate (), with or without additives, typically extruded between thick sheets of ...
Although gypsum is a widely used material in the construction industry, phosphogypsum is usually not used, but is stored indefinitely because of its weak radioactivity caused by the presence of naturally occurring uranium (U) and thorium (Th), and their daughter isotopes radium (Ra), radon (Rn) and polonium (Po).
Plaster was first used as a building material and for decoration in the Middle East at least 7,000 years ago. In Egypt, gypsum was burned in open fires, crushed into powder, and mixed with water to create plaster, used as a mortar between the blocks of pyramids and to provide a smooth wall facing.
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With judicious heating, gypsum converts to the partially dehydrated mineral called bassanite or plaster of Paris. This material has the formula CaSO 4 ·(nH 2 O), where 0.5 ≤ n ≤ 0.8. [8] Temperatures between 100 and 150 °C (212–302 °F) are required to drive off the water within its structure.