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单词 cement
释义
cement

Chemistry
  • Any of various substances used for bonding or setting to a hard material. Portland cement is a mixture of calcium silicates and aluminates made by heating limestone (CaCO3) with clay (containing aluminosilicates) in a kiln. The product is ground to a fine powder. When mixed with water it sets in a few hours and then hardens over a longer period of time due to the formation of hydrated aluminates and silicates.


Chemical Engineering
  • A widely used material in the construction industry which, when mixed with sand and aggregates, is used in the construction of buildings, bridges, and roads. The raw materials in its manufacture are limestone, silica-rich clay, gypsum (used to control the hardening process), and other materials such as sand or slag from a blast furnace used to adjust the mix. They are finely ground and burnt in a kiln at 1,500ºC to form clinker. The clinker is formed due to reactions and the evaporation of water, and results in the formation of carbon dioxide. Cement is chemically unstable. When water is added, it cures gradually hardening.


Biology
  • A thin layer of bony material that fixes teeth to the jaw. It covers the dentine of the root of a tooth, below the level of the gum, and is attached to the periodontal membrane lining the tooth socket in the jawbone.


Geology and Earth Sciences
  • 1. Manufactured powder made from limestone and clay which sets to a solid mass when mixed with water. Commercial cements have to fulfil certain defined standards. Combined with aggregate it forms concrete.

    2. Material, e.g. calcite, that fills open pore space in fragmental and organic sediments.


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