Monday, October 7, 2013


Accelerating admixtures are added to concrete to increase the rate of early strength development in concrete to
  • Permit earlier removal of formwork
  • reduce the required period of curing
  • Advance the time that a structure can be placed in service
  • Partially compensate for the retarding effect of low temperature during cold weather concreting
  • In the emergency repair works
 Calcium chloride is the material very commonly used as accelerator.

The action of calcium chloride is assisting concreting at low temperature is three fold as-
  • It lowers the temperature at which freezing of the wet mixture takes place
  • It helps to keep the mixture warm by accelerating the generation of heat by chemical action 
  • It increases the ability of the concrete to resist frost action by speeding up the rate of gain of strength
Effects of calcium chloride on concrete:
  • Increases volume changes in concrete 
  • Increases the alkali-aggregate reaction 
  • Reduces the resistance of concrete  to sulphate attack

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