Editing Accelerant (section)

=== Cement and concrete ===
{{Main|Cement accelerator}}

Cement accelerators are available as [[admixture (concrete)|admixtures]] for use in [[concrete]], [[mortar (masonry)|mortar]], [[cement render|render]], and [[screed]]. The addition of an accelerator speeds the setting time and thus [[curing (chemistry)|curing]] starts earlier.<ref name="Justnes">Justnes, H. (2000): Accelerator Blends for Portland Cement. Proceedings of Cement and Concrete Technology in the 2000s, September 6–10, 2000, Istanbul, Turkey, Vol. 1, pp.&nbsp;433&ndash;442</ref> This allows concrete to be placed in winter with reduced risk of [[frost damage (construction)|frost damage]].<ref name="ACI">ACI 306R-88: Cold Weather Concreting. {{cite web |title=Cold Weather Concreting |website=Concrete Contractors Association of Greater Chicago |url=http://www.ccagc.org/pdfs/ACI_306R-88_Cold_Weather_Concreting.pdf |access-date=2011-03-05 |url-status=dead |archive-url=https://web.archive.org/web/20110725150450/http://www.ccagc.org/pdfs/ACI_306R-88_Cold_Weather_Concreting.pdf |archive-date=2011-07-25}}</ref> Concrete is damaged if it does not reach a strength of {{convert|500|psi|MPa}} before freezing.{{sfn|Korhonen|Cortez|Durning|1997|p=19}} Typical cement accelerators are [[calcium nitrate]] ({{chem|Ca|(NO|3|)|2}}), [[calcium formate]] ({{chem|Ca|(HCOO)|2}}), and [[sodium nitrate]] ({{chem|Na|N|O|3}}).<ref>{{cite journal |last1=Korhonen |first1=Charles J. |last2=Cortez |first2=Edel R. |last3=Durning |first3=Timothy A. |date=1997 |title=Antifreeze Admixtures for Concrete |journal=[[Cold Regions Research and Engineering Laboratory]] |volume=Special Report 97-26 |isbn=9781428913158}}</ref>