Synopsis
Details are given of a novel test rig developed to investigate the creep of concrete under varying temperature. Tubes of saturated mortar were subjected to sustained torsional load, and the creep in shear was measured. The results showed that, when the temperature was raisedfor the first time, the creep rate increased greatly in comparison with that of a similar specimen heated before loading. No such change of rate was observed when the temperature was lowered or when it was raised to a level previously attained. It is shown that creep under variable temperature may be considered as the sum of three components: under constant temperature, flow (irrecoverable) and delayed elastic strain (recoverable); and as a result of the first temperature rise, transitional thermal creep (irrecoverable).
