ABSTRACT
The hydration of portland cement is exothermic and the total heat produced can be as high as 500 kJ/kg. In large concrete pours, where the heat of hydration dissipates very slowly, signicant temperature rises in the range of 12 to 14°C per 100 kg (8 to 10°F per 100 lb) cement can occur (FitzGibbon, 1976a, 1976b), which can result in peak internal concrete temperatures as high as 80°C (176°F) or more in certain cases. When concrete cools from its peak temperature it contracts, and thermal cracking can occur if the contraction is restrained externally or if signicant thermal gradients occur within the concrete mass (for example, if the external surface cools much more rapidly than the internal bulk). One way to reduce the risk of thermal cracking is to reduce the peak internal temperature of the concrete.
