A predictive phase-field approach for cover cracking in corroded concrete elements

Abstract

Steel bar corrosion is a crucial problem in reinforced concrete structures. Corrosion, being one of the most prevalent deterioration mechanism in concrete elements, has a significant impact on the structure's serviceability and durability, since the cross section of the steel reinforcement is reduced and the mechanical steel performances deteriorate. Additionally, residual material is created as a result of the steel oxidation process, and the volume occupied by the reinforcement grows, forcing the concrete cover to crack and spall. The carbonation-induced rebar corrosion and the subsequent cover cracking are simulated via the usage of a predictive model which combines the concrete carbonation process with the phase-field technique for brittle fractures. First, the carbon dioxide transport within the concrete is described using the Fick’s second diffusion law. Then, the corrosion process is estimated via the electrochemical kinetics equations providing the associated steel expansion. The steel deformation and strain are calculated with the Faraday Law. Finally, a phase field approach for brittle material is used to reproduce rupture in the concrete cover. The developed model is validated against examples available in literature and representative examples are illustrated, describing the capability of the proposed approach to replicate the cover cracking in concrete.