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THERMAL MOVEMENT IN CONCRETEAs with any material, concrete will expand and contract as the temperature rises and falls. The size of movement depends upon the change in temperature and the coefficient of thermal expansion o f concrete. The coefficient of thermal expansion of concrete is influenced largely by the coefficient of thermal expansion of the aggregates since the aggregate occupies 70-80% of the volume of the concrete. Some typical examples of the thermal expansion coefficient of concrete are shown plotted against those of aggregates.
Fig: Thermal expansion of concreteKnowledge of the magnitude of the thermal movement is necessary to evaluate the risk of thermal cracking in situations where large thermal gradients are likely to occur, and to calculate dimensional changes in structures such as bridge decks.