Influence of loading history upon the tensile properties of concrete

Abstract

Synopsis In this paper, the influence of sustained and cyclic load regimes upon the tensile properties of concrete and paste is reported. The results indicate that prior loading of any form reduces the strength of concrete on reloading. For paste, however, the effect is not so marked and a slight increase in strength is observed after cyclic preloading. Strain to peak stress on reloading follows the same trends as strength, whilst the elastic modulus of both paste and concrete is reduced on reloading, irrespective of the mode of previous loading. It is considered that, for concrete, the damage resulting from the initial loading produces limited microcracking at the aggregate-matrix interface, which propagates due to a time- (and load-) dependent mechanism previously proposed. For cement paste, the initial damage and hence microcracking is much less and hence the consequent effect of the prior loading regimes upon the properties of the paste is also less than for concrete.