Title: Electrochemical Modeling of Cathodic Protection Systems Applied to Reinforced Concrete Structures

Abstract approved A numerical model for the cathodic protection of steel in reinforced concrete is developed. Parameters are set to represent a three-dimensional section of a bridge beam exposed to the atmosphere and coated with a thermally sprayed zinc anode. Both diffusion of oxygen and conduction of charge within the concrete are considered explicitly through a two-dimensional finite element model. The diffusivity and conductivity are represented as functions of concrete moisture content. Electrochemical reactions considered at the rebar-concrete interface are reduction of oxygen, oxidation of iron, and evolution of hydrogen in a constant-potential cathodic protection circuit. Reaction-kinetic parameters for actively corroding steel (not passivated steel) are used. Reactions at the zinc-concrete interface are not considered explicitly. The effectiveness of protection is found to vary significantly with both concrete moisture content and position on the rebar. For spatially uniform pore saturation, the drier the concrete is, the greater the corrosion current and the greate