Drying shrinkage and drying creep strains represent significant components of the delayed strains occurring in concrete. Natural drying, induces not only deformation throughout the material but also a strong structural effect: the skin of the concrete dries much more quickly…
Drying shrinkage and drying creep strains represent significant components of the delayed strains occurring in concrete. Natural drying, induces not only deformation throughout the material but also a strong structural effect: the skin of the concrete dries much more quickly than the core, thereby generating tension at the skin and ultimately leading to cracking. Supported by a series of tests conducted by Granger, we will demonstrate that a model of concrete's drying and an scalar elasto-plastic damage approach enable recre- ating a considerable number of experimental phenomena for drying structures (loaded and unloaded). Indeed, for unloaded structures, the observed initial cracking phase and proportional shrinkage I weight loss are prop- erly described for thick specimens. Further, the model reproduces the additional asymptotic shrinkage phase due to crack opening I closure in the case of thin specimens for which the drying is a short time process. Moreover, cracks occur at the skin of the concrete, even in the case of a compressive loading. Cracking is less pronounced in this case, but leads to an additional time-dependent deformation, namely the structural drying creep strain. Numerical simulation shows that this strain increases rapidly in the skin of the concrete, which can not bee neglected, since its value is of the same order of the elastic one. A comparison of experimental re- sults with numerical results is made and points out that the model is able to reproduce accurately the evolution of drying shrinkage and drying creep strains.