Chemo-Mechanical Modeling Requirements for the Assessment of Concrete Structure Service Life

Abstract

This paper deals with the formulation requirements for the finite-element modeling of the life cycle of concrete structures subjected to chemical evolution combined with mechanical loading. In particular, it considers the coupling of chemical evolution with nonlinear mechanical behavior combining creep and damage. Not only do the parameters of the mechanical model have to be adapted to the effect of chemical evolution, but also the chemical effects on the internal mechanical state variables of the chemical evolution have to be carefully considered. These two couplings are discussed and clarified in a general formulation useful for a finite-element implementation of a mechanical behavior law intended for chemo-mechanical applications. The approach is illustrated through a model developed to assess the mechanical behavior of concrete structures subjected to hydration and then to leaching during their service life. Hydration and leaching need to be considered together in the same model to study how damage of the concrete at its early age can affect its response in the long term. The model is implemented in a finite-element code and applied, first to the simulation of an early age creep test and then to the prediction of the very-long-term mechanical behavior of a nuclear waste storage facility.