| Calcium silicate | |
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Calcium silicate |
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Dicalcium silicate |
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Other names
Belite Calcium orthosilicate |
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| Identifiers | |
| CAS number | 1344-95-2 , 111811-33-7 hydrate , 12168-85-3 calcium oxide |
| PubChem | 14941, 44154858 hydrate, 25523 calcium oxide |
| ChemSpider | 14235 , 23811 calcium oxide |
| UNII | S4255P4G5M |
| EC number | 235-336-9 |
| KEGG | D03309 |
| MeSH | Calcium+silicate |
| ATC code | A02 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | Ca2O4Si |
| Molar mass | 172.24 g mol−1 |
| Exact mass | 171.881767331 g mol-1 |
| Appearance | White crystals |
| Melting point |
1540 °C, 1813 K, 2804 °F |
| Hazards | |
| MSDS | [1] |
| Main hazards | Irritant |
| NFPA 704 |
0
2
0
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| Flash point | Not applicable |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Calcium silicate (often referred to by its shortened trade name Cal-Sil or Calsil) is the chemical compound Ca2SiO4, also known as calcium orthosilicate and sometimes formulated 2CaO.SiO2. It is one of group of compounds obtained by reacting calcium oxide and silica in various ratios[2] e.g. 3CaO.SiO2, Ca3SiO5; 2CaO.SiO2, Ca2SiO4; 3CaO.2SiO2, Ca3Si2O7 and CaO.SiO2, CaSiO3. Calcium orthosilicate is a white powder with a low bulk density and high physical water absorption. It is used as an anti-caking agent and an antacid. A white free-flowing powder derived from limestone and diatomaceous earth, calcium silicate has no known adverse effects to health. It is used in roads, insulation, bricks, roof tiles, table salt[3] and occurs in cements, where it is known as belite (or in cement chemist notation C2S).
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Calcium silicate is commonly used as a safe alternative to asbestos for high temperature insulation materials. Industrial grade piping and equipment insulation is often fabricated from calcium silicate. Its fabrication is a routine part of the curriculum for insulation apprentices. Calcium silicate competes in these realms against rockwool as well as proprietary insulation solids, such as perlite mixture and vermiculite bonded with sodium silicate. Although it is popularly considered an asbestos substitute, early uses of calcium silicate for insulation still made use of asbestos fibers.
One of the most successful materials in fireproofing in Europe is calcium silicate. Where North Americans use spray fireproofing plasters, Europeans are more likely to use cladding made of calcium silicate. Calcium silicate is easily damaged by water. Therefore, silicone treated sheets are available to fabricators to mitigate potential harm from high humidity or general presence of water. Fabricators and installers of calcium silicate in passive fire protection often also install firestops.
Calcium silicate is also a constituent of the slag that is produced when molten iron is made from iron ore and calcium carbonate in a blast furnace. When this material is processed into a highly refined, repurposed calcium silicate aggregate, it is used in the remediation of acid mine drainage (AMD) on active and passive mine sites.[4] Calcium silicate neutralizes active acidity in AMD systems by removing free hydrogen ions from the bulk solution, thereby increasing pH. As its silicate anion captures H+ ions (raising the pH), it forms monosilicic acid (H4SiO4), a neutral solute. Monosilicic acid remains in the bulk solution to play other important roles in correcting the adverse effects of acidic conditions. As opposed to limestone (a popular remediation material),[5] calcium silicate effectively precipitates heavy metals and does not armor over, prolonging its effectiveness in AMD systems.[4][6]
When sodium silicate is applied as a sealant to cured concrete or the shells of fresh eggs, it chemically reacts with calcium hydroxide or carbonate to form calcium silicate hydrate, sealing pores with a relatively impermeable material.
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