Editing Calcium silicate (section)

==Use==
===As a component of cement===
Calcium silicates are the major ingredients in [[Portland cement]]s.<ref>{{cite book |doi=10.1002/14356007.a05_489.pub2 |chapter=Cement |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2008 |last1=Sprung |first1=Siegbert |isbn=978-3-527-30385-4 }}</ref>

{|class=wikitable
|+ Typical constituents of portland clinker plus gypsum<br><small> showing [[cement chemist notation]] (CCN)</small>
! Clinker
! CCN
! Mass
! Mineral
|-
|Tricalcium silicate (CaO)<sub>3</sub> · SiO<sub>2</sub>||C<sub>3</sub>S|| 25–50%|| [[alite]]
|-
| Dicalcium silicate (this article) (CaO)<sub>2</sub> · SiO<sub>2</sub>||C<sub>2</sub>S|| 20–45%||[[belite]]
|-
|[[Tricalcium aluminate]] (CaO)<sub>3</sub> · Al<sub>2</sub>O<sub>3</sub>||C<sub>3</sub>A|| 5–12%
|-
|[[Calcium Aluminoferrite|Tetracalcium aluminoferrite]] (CaO)<sub>4</sub> · Al<sub>2</sub>O<sub>3</sub> · Fe<sub>2</sub>O<sub>3</sub>||C<sub>4</sub>AF|| 6–12%
|-
|CaSO<sub>4</sub> · 2 H<sub>2</sub>O||CS̅H<sub>2</sub>|| 2–10%||[[gypsum]]
|}

===High-temperature insulation===
[[File:Calcium silicate cladding 2of2.jpg|thumb|left|Calcium-silicate [[passive fire protection]] board being clad around steel structure in order to achieve a [[fire-resistance rating]]]]
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 [[apprentice]]s. Calcium silicate competes in these realms against [[Mineral wool|rockwool]] and proprietary [[Thermal insulation|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.

===Passive fire protection===
[[File:Promat signum tray cladding 1.jpg|thumb|left|[[Circuit integrity]] [[fireproofing]] of [[cable tray]]s in Lingen/Ems, [[Germany]] using calcium-silicate board [[system]] qualified to DIN 4102. Other methods for exterior protection of electrical circuits include boards made of [[sodium silicate]], bonded and pressed [[vermiculite]], and flexible wraps made of ceramic fibre and rockwool.]]
It is used in [[passive fire protection]] and [[fireproofing]] as [[calcium silicate brick]] or in roof tiles. It is one of the most successful materials in [[fireproofing]] in [[Europe]] because of regulations and fire safety guidelines for commercial and residential building codes. Where [[North America]]ns use spray fireproofing [[plaster]]s, Europeans are more likely to use [[cladding (construction)|cladding]] made of calcium silicate. {{why|date=December 2012}} High-performance calcium-silicate boards retain their excellent dimensional stability even in damp and humid conditions and can be installed at an early stage in the construction program, before wet trades are completed and the building is weather-tight. For sub-standard products, [[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 [[firestop]]s.{{citation needed|date=July 2017}}

While the best possible reaction to fire classifications are A1 (construction applications) and A1Fl (flooring applications) respectively, both of which mean "non-combustible" according to EN 13501-1: 2007, as classified by a notified laboratory in Europe, some calcium-silicate boards only come with fire classification of A2 (limited combustibility) or even lower classifications (or no classification), if they are tested at all.{{citation needed|date=July 2017}}

===Acid mine drainage remediation===
Calcium silicate, also known as [[slag]], is produced when molten [[iron]] is made from [[iron ore]], [[silicon dioxide]] and [[calcium carbonate]] in a [[blast furnace]]. When this material is processed into a highly refined, re-purposed calcium silicate aggregate, it is used in the remediation of [[acid mine drainage]] (AMD) on active and passive mine sites.<ref name="steel slag">{{cite web|last=Ziemkiewicz|first=Paul|title=The Use of Steel Slag in Acid Mine Drainage Treatment and Control|url=http://wvmdtaskforce.com/proceedings/98/98zie/98zie.htm|website=Wvmdtaskforce.com|access-date=25 April 2011|url-status=dead|archive-url=https://web.archive.org/web/20110720064631/http://wvmdtaskforce.com/proceedings/98/98zie/98zie.htm|archive-date=20 July 2011}}</ref> 
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<sup>+</sup> ions (raising the pH), it forms monosilicic acid (H<sub>4</sub>SiO<sub>4</sub>), 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),<ref>{{cite web|last=Skousen|first=Jeff|title=Chemicals|url=http://www.wvu.edu/~agexten/landrec/chemtrt.htm#Chemicals|work=Overview of Acid Mine Drainage Treatment with Chemicals|publisher=West Virginia University Extension Service|access-date=29 March 2011|url-status=dead|archive-url=https://web.archive.org/web/20110524070234/http://www.wvu.edu/~agexten/landrec/chemtrt.htm#Chemicals|archive-date=24 May 2011}}</ref> calcium silicate effectively precipitates heavy metals and does not armor over, prolonging its effectiveness in AMD systems.<ref name="steel slag"/><ref>{{cite journal|last=Hammarstrom|first=Jane M.|author2=Philip L. Sibrell|author3=Harvey E. Belkin|title=Characterization of limestone reacted with acid-mine drainage|journal=Applied Geochemistry|issue=18|pages=1710–1714|url=http://mine-drainage.usgs.gov/pubs/AG_18-1705-1721.pdf|access-date=30 March 2011|archive-date=5 June 2013|archive-url=https://web.archive.org/web/20130605231303/http://mine-drainage.usgs.gov/pubs/AG_18-1705-1721.pdf|url-status=dead}}</ref>

===As a product of sealants===
It is used as a sealant in roads or on the shells of fresh [[egg (food)|eggs]]: when [[sodium silicate]] is applied as a sealant to cured [[concrete]] or egg shells, it chemically reacts with [[calcium hydroxide]] or [[calcium carbonate]] to form calcium silicate hydrate, sealing micropores with a relatively impermeable material.<ref>{{cite journal | last1 = Giannaros | first1 = P. | last2 = Kanellopoulos | first2 = A. | last3 = Al-Tabbaa | first3 = A. | year = 2016 | title = Sealing of cracks in cement using microencapsulated sodium silicate | journal = Smart Materials and Structures | volume = 25 | issue = 8| page = 8 | doi = 10.1088/0964-1726/25/8/084005 | bibcode = 2016SMaS...25h4005G | doi-access = free }}</ref><ref>{{cite journal | last1 = Passmore | first1 = S. M. | year = 1975 | title = Preserving eggs | journal = Nutrition & Food Science | volume = 75 | issue = 4| pages = 2–4 | doi = 10.1108/eb058634 }}</ref>

===Agriculture===
Calcium silicate is often used in agriculture as a plant available source of silicon. It is "applied extensively to Everglades mucks and associated sands planted to sugarcane and rice" <ref>{{cite journal|last=Gascho|first=Gary J.|title=Chapter 12 Silicon sources for agriculture|journal=Studies in Plant Science|volume=8|issue=8|pages=197–207|doi=10.1016/S0928-3420(01)80016-1|year=2001|isbn=9780444502629}}</ref>

===Other===
Calcium silicate is used as an [[anticaking agent]] in food preparation, including table salt<ref name="mortonsalt1">[http://www.mortonsalt.com/faqs/food_salt_faq.html#q6] {{webarchive|url=https://web.archive.org/web/20081225045630/http://www.mortonsalt.com/faqs/food_salt_faq.html|date=2008-12-25}}</ref> and as an [[antacid]]. It is approved by the United Nations' [[FAO]] and [[WHO]] bodies as a safe [[food additive]] in a large variety of products.<ref>
{{cite web| title = Food Additive Details: Calcium silicate| url = http://www.codexalimentarius.net/gsfaonline/additives/details.html?id=315| access-date = July 28, 2013| archive-url = https://web.archive.org/web/20120605054550/http://www.codexalimentarius.net/gsfaonline/additives/details.html?id=315| archive-date = June 5, 2012
}} ''Codex General Standard for Food Additives (GSFA) Online Database'', FAO/WHO Food Standards Codex alimentarius, published by the Food and Agricultural Organization of the United Nations / World Health Organization, 2013.</ref> It has the [[E number]] reference '''E552'''.

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