Heat Of Hydration

Summary

Heat Of Hydration - is the release of heat during concrete curing.

Technical Information

Heat of hydration can be problematic in deep pours as it can cause large differential temperature gradients between the centre and the surface of deep concrete members; leading to thermal cracking.

Another problem associated with the heat of hydration in concrete floor slabs is early thermal shrinkage. This is where the concrete maintains a much higher temperature than its surroundings as it is hydrating quickly in the early phases of its strength development. After the concrete has set, hydration starts to slow down and cool to the ambient temperature. This will cause the slab to shrink and, if restrained, crack.

In Portland cement the gypsum component is responsible for the steady hydration of the concrete; in turn ensuring undesirable temperatures aren’t reached. The peak temperature reached in a slab can be reduced by using cement replacing materials which hydrate more slowly, such as GGBFS.