Creep of Concrete in Compression During Drying and Wetting

SYNOPSIS The paper describes a study of concrete creep during drying-and-wetting regimes. Damp specimens were loaded at ages of 7 or 140 days and drying began at intervals thereafter. Drying creep was observed; its rate of development was linearly related to that of concurrent shrinkage. The correlation was independent of age at loading and of delay in drying, and only mildly dependent upon stress. For different concretes, drying creep can be closely predicted from water/cement ratio or 28 day strength. The creep recoveries of drying specimens were greater than those of damp specimens; drying creep was recoverable to the same extent as basic creep. No additional recovery of drying creep was observed upon rewetting unloaded specimens. Specimens rewetted under load exhibited wetting creep which was linearly related to concurrent swelling. Reference is made to the calculation in practice of strains in concrete subjected to stress and varying humidity. The nature of drying creep is discussed briefly.