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What is gypsum ? Why is gypsum widely used in the building industry... Print E-mail



  • What is gypsum ? Why is gypsum widely used in the building industry around the globe ? Which country that first produced gypsum plasterboard ? 







  • Gypsum (gypse as in French / gypsos as in Greek), chemically formulated as CaSO4.2H2O, is calcium sulphate dihydrate. Gypsum is often found in nature as sedimentary rock in underground mines or open pits. Under the effects of high temperature and pressure, gypsum rock is naturally formed about 160 to 200 million years ago as a combination between Ca(2+), SO4(2-) and water (H2O), which are abundant in seas and oceans. In pure form, gypsum rock is white, but in many cases, its colour might be pink, brown, yellow, grey, etc. depending on its impurities.

  • When heated in a certain time length and temperature, gypsum partly loses its water molecules and turns to plaster, chemically formulated as  CaSO4.1/2H2O, known as calcium sulphate hemihydrate. By then, the rock becomes soft, porous, easy for grinding into fine powder particles. Plaster is an unstable product, always tends to absorb and react with water to turn back to its original state, that is gypsum. Taking advantage of this feature, through series of industrial processes, human being has produced many gypsum based products used in the building and construction industry. Just name a few: gypsum plasterboards or wallboards, fibrous cast gypsum boards, plaster compounds for jointing and bonding, moulding plasters for ceramic industry, ground gypsum as soil conditioner, etc.

  • Depending on fire protection requirements, various building structures such as floors, walls, ceilings, roofs, beams, joists, columns are lined with special fire resistant gypsum boards to achieve a fire resistance level from 30 minutes (0.5 hours) up to 240 minutes (4 hours). This excellent feature results from the water molecules chemically combined in gypsum crystals matrix, which make up to 50% in volume or 21% in weight: when exposed to hot flames, water is gradually released from gypsum and forms a vapour barrier, preventing the temperature of the building components just behind layers of gypsum lining boards from far exceeding 100 degres C. This is similar to the temperature of boiling water at normal atmospheric pressure.

  • In 1894, Augustine Sackett, an American businessman, invented the process of producing industrial gypsum boards. In the early days, the product consisted of alternate layers of papers and gypsum. Nowadays, gypsum plasterboard is manufactured from fully automatic production lines, with a gypsum core mixed with selected additives, sandwiched between special kraft paper liners that embrace the front and back faces and two long edges.

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