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construction science and materials
Member rating: No Rating | Words: 4117 | Submitted: Sat Jun 02 2007
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Construction science and materials: Assessment No 4: TASK 1 Production and manufacturing processes: LIME: Lime is made by heating chalk or limestone (both calcium carbonate, CaCO3) to a temperature of 900° in a kiln. The heating breaks down the limestone to produce quicklime (calcium oxide, CaO) and carbon dioxide gas (CO2). The chemical reaction is shown below: CaCO3 Heat CaO CO2 + Limestone 900°C quick lime carbon dioxide When quicklime is added to water the quicklime combines with the water to form hydrated lime (calcium hydroxide Ca (OH) 2.) This process is known as slaking. The chemical reaction, which takes place, is shown below: CaO H2O Ca (OH) 2 + Quicklime Water Hydrated lime GYPSUM PLASTER: Gypsum plaster is made from gypsum, whish is naturally occurring rock (calcium sulphate dihydrate, CaSO4 .2H 20). The gypsum is quarried, crushed and ground to a fine powder. The gypsum is then heated to drive off some or all of the water. If the gypsum is heated to 150°C, then only some of the...
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