Nonlinear Coupling of Carbonation and Chloride Diffusion in Concrete

External reinforced concrete elements exposed to chloride and/or CO2 will eventually have a lower pH, which in turn will depassivate the reinforcement and initiate corrosion, thus causing spalling. This paper seeks to address the complex multiphysics nature of concrete environmental damage, which is governed by coupled nonlinear partial differential equations. Heat, relative pore humidity, chloride, and carbonation are all implemented in a two-dimensional coupled nonlinear finite-difference code. Coupling between carbonation and chloride diffusion is explored in the context of both homogeneous and heterogeneous concrete models. Numerical simulations results are presented.