Cement accelerator

A cement accelerator is an admixture for the use in concrete, mortar, rendering or screeds. The addition of an accelerator speeds the setting time and thus cure time starts earlier.[1] This allows concrete to be placed in winter with reduced risk of frost damage.[2][3]

Typical chemicals used for acceleration today are calcium nitrate (Ca(NO3)2) and sodium nitrate (NaNO3). Formerly Calcium chloride (CaCl2) has been very popular, but due to its corroding behaviour for reinforcement bars its use is according CAA ATS4 [4] not recommended and in many countries actually prohibited. Sodium compounds might compromise the long term compressive strength.[5]

References

  1. ↑ 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. 433-442
  2. ↑ Korhonen, C.J., Cortez, E.R. and Durning, T.A. (1997): Antifreeze Admixtures for Concrete. Special Report 97-26. Cold Regions Research & Engineering Laboratory, US Army Corps of Engineers
  3. ↑ ACI 306R-88: Cold Weather Concreting. http://www.ccagc.org/pdfs/ACI_306R-88_Cold_Weather_Concreting.pdf
  4. ↑ CEMENT ADMIXTURES ASSOCIATION: Admixture Sheet – ATS 4: Accelerating admixtures, http://www.admixtures.org.uk/downloads/ATS%204%20Accelerating%20admixtures.pdf
  5. ↑ Volset, D.(2010): The Use of Antifreeze Agents. http://www.mapei.com/public/NO/linedocument/the_use_of_anti-freeze_agents.pdf


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