Study of the size effect in a model to simulate concrete cracking due to rebar corrosion and comparison to accelerated corrosion tests

Abstract

An immediate consequence of the corrosion of reinforcement in concrete structures consists in the generation of an oxide layer at the steel surface which, due to the greater specific volume of the oxide with respect to the steel, induces internal pressure on the surrounding concrete and thus cracks the concrete cover [1, 3]. Focussing on the prediction of the mechanical effects of the oxide expansion, a numerical model to simulate the effect of the oxide layer was programmed, assuming that the oxide layer expansion is given at a any specified time [5]. The basic ingredient of such a model is an interface element with zero initial thickness that incorporates both the expansive and mechanical behaviors of the oxide, which is characterized by its ability to debond, with nearly free sliding (very small shear stiffness) and nearly free separation in tension (strongly reduced normal tension stiffness). It was called expansive joint element and it has already been presented in previous conferences. Concrete cracking is simulated by finite elements with embedded adaptable cohesive cracks [4] that follow the basic cohesive crack model proposed by Hillerborg