Synopsis
Measurements of the coefficient of thermal expansion of different aggregates, and of concretes prepared from them with different cements, have been made over the temperature range 32°F. to 104°F.
The values for aggregates have been found to range from 2.1 to 6.5 × l0-6 per °F. Siliceous materials have the highest coefficients, limestones the lowest, and igneous materials intermediate.
Concretes have values in the range 3.4 to 7.3 × 10-6 per °F. The magnitude of the coefficient of expansion of concrete depends largely on the aggregate used; concretes with siliceous aggregate have the highest values and those with limestone aggregate the lowest, whilst concretes with igneous aggregate have intermediate values.
The coefficient of thermal expansion of neat hydrated cement is higher than that of any aggregate measured. The richer mixes tend to have the higher thermal expansion but the order of difference is not high; the age of concrete has little effect on its thermal expansion.
The method of curing and the water content have only a small influence on the thermal expansion. Desiccated and water-saturated concretes have similar coefficients of expansion but the values are lower than that of partly-dry concrete.
