AGE, ENVIRONMENT AND FRACTURED CONCRETE

This article is concerned with the behaviour of fractured concrete. After a brief outline of earlier investigations, the authors give details of a series of experiments that they have carried out to study the effect of age and environment on the healing of fractured concrete. Their results show that water-cured concrete heals better than air-cured concrete and that the best ability to heal occurs when stressing takes place at 14 days (when it was found to be stronger at 28 days than when unstressed). They also found that the strength of concrete diminished when exposed to a dry atmosphere and subsequently fractured at ages of 60 days or more. Other findings were:- that whilst environment and age affected both pre-and post-failure stress-strain characteristics, post-failure was affected to the greater extent; that pre-failure sustained loads had little effect on post-failure behaviour whereas post-failure sustained loads resulted in a reduction in strength; that post-failure cyclic loading increased residual strength and that the effect of sustained loading on concrete previously loaded to maximum stress was to increase strength to values greater than the corresponding strength of the concrete not previously subjected to loading. /TRRL/