Modelling of 3D periodic cathodic protection problems in reinforced concrete structures with accelerated boundary element method

Abstract

The steel used for concrete reinforcement exhibits either active or passive electrochemical behavior. As long as the concrete environment remains highly alkaline, the steel remains passive. However, carbonation and/or chloride contamination of concrete will cause steel to become active and corrode. In the latter case, a common strategy is the use of cathodic protection (CP) systems to lower the potential of the steel at a protective level. The numerical modelling of cathodically protected concrete buildings and infrastructures usually requires large-scale models due to their size and complex geometry. An efficient modelling approach is to consider any possible periodicity in these problems by applying periodic boundary conditions to a representative volume element of the structure. The boundary element method (BEM) is extensively used for solving CP problems. A BEM formulation is proposed for solving 3D periodic CP problems in this work. The computation cost is reduced by applying acceleration techniques based on adaptive cross approximation (ACA). As an engineering application, a sacrificial anode CP system of a reinforced concrete column is designed, illustrating the importance of detailed modelling in the design of such systems. To this end, the macrocell corrosion problem is initially solved, and a parametric study with respect to concrete conductivity is carried out.