Abstract:
The hydration of cement is an exothermic reaction, which begins almost immediately
upon contact with water. This produces a large amount heat that subsequently raises
the temperature of the concrete mixture, creating a temperature gradient across the
member. The temperature rise associated with hydration induces thermo-mechanical
stresses. These stresses can cause damage to the structure, affecting the durability and
in extreme cases the functionality of the structure. If the maximum rate of heat
evolution experienced can be minimised through the selection of the constituents of a
concrete mixture, then the thermal stresses that develop in the concrete can be
reduced. The main aim of this research is to develop a knowledge of how the heat
evolution characteristics of concrete are affected by changing certain concrete
mixture parameters and ingredients. The focus is on the addition of three different
cement extenders and varying the water/cement ratio. This will be a step towards the
development of a model for predicting the thermal properties of concrete. As a part of
this investigation, a prediction model for the change in heat rate in concrete was
developed. The model is intended to predict the contribution of the individual clinker
crystallographic phases in cement and the heat liberated in concrete during hydration.
