Drying of concrete : modelling of a hydric damage
Résumé
Drying shrinkage of concrete induces the formation of microcracks that damage concrete structures.This damage can be characterised by deteriorating material elastic prop- erties over the years.In this investigation,we present a modelling of this phenomenon,simple and easy to be implemented,and that should allow engineers to predict cracking as a durability indicator and to model ageing.We first present the basic hypotheses of our model,and for- mulate hydric damage by using an isotropic scalar variable proportional to the decrease in water content. Uncoupling between drying-induced damage and classicalmechanical damage is assumed.Two simple applications are proposed.For the one-dimensional drying case (cylin- drical specimens),we compare the simulation of the varia- tion in time of the dimensionless stiffness with experi- mental results in uniaxial compression.A good adequacy is observed.For the bi-dimensional drying case (prismatic specimens),the knowledge of measurements of mass loss and average longitudinal shrinkage in time allows us to predict the value of drying induced stresses in a cross sec- tion,taking hydric damage into account.A better estimate of stresses induced by drying is proposed.