The goal of this project, which was developed in response to the Durability Initiative, NSF 98-42, is to formulate and validate a model which can use results from accelerated tests to improve the performance of cathodic protection systems for concrete structures. Existing data and the current understanding of the following processes will be incorporated within a comprehensive three-dimensional model: (i) the electrochemical kinetics of iron oxidation, oxygen reduction, and water reduction at the concrete-rebar interface; (ii) the electrochemical kinetics of zinc anode oxidation and subsequent reactions of Zn(II) at the concrete-zinc interface; (iii) the transport of water and oxygen through concrete; and (iv) the transport of ions, particularly chloride, through concrete. The model will be validated in laboratory tests and then used to investigate strategies for controlling cathodic protection systems for optimal performance, for avoidance of buildup of electrical resistance at the anode-concrete interface, and for electrochemical migration of chlorides away from the rebar. The model will finally be field-tested in suitable real structures. ***
