Friday, August 22, 2008

Effects of high temperature on concrete

Concrete is essentially a mixture of cement, aggregate and water. Its qualities are greatly affected by temperature during mixing, placing and compacting.

High temperatures can have the following effects on concrete:

  • reduced setting times and early stiffening
  • increase in the rates of hardening
  • loss of 28 day strength
  • increase in tendency for plastic shrinkage
  • difficulties in the operations of placing and finishing
  • development of cold joints - a cold joint is formed when plastic concrete is placed against concrete that has set and started hardening.

Admixtures are added to control these effects of hot temperature.