Executive Summary : | Cathodic protection (CP) systems with galvanic anodes have gained popularity in concrete repair industry as an electrochemical repair treatment to arrest the corrosion of steel and extend the service life of the structures. The currently used inspection/assessment techniques and acceptance criteria available for CP system in concrete are derived from metals in low-resistive electrolytes (ship in seawater, pipelines in soil, etc.). This project will first assess the feasibility of existing test methods for long-term and routine performance assessment of anodes embedded in concrete (with much higher resistivity than seawater or soil). Also, there are practical difficulties in installing and maintaining monitoring boxes for long term for these tests. The proposed work will assess the feasibility and efficiency of the existing test methods (say, EN ISO 12696) for the routine/non-destructive inspection and long-term performance assessment of galvanic anodes in reinforced concrete systems. Then, the electrical and electrochemical characteristics of the concrete-steel-anode (CSA) system will be determined using laboratory studies. Following this, an electrochemical model that can estimate the potential and current distribution in a three-dimensional CSA element will be developed using a finite element method. In addition, an electrical model of the CSA system will be developed to establish correlation between the electrical response parameters and the connected potential/normal current density at various points in the actual concrete specimens. Based on these data, an electrical and electrochemical (EEC) model will be developed and the instantaneous performance of the galvanic anodes in CSA systems will be assessed. Then, the response of CSA systems against a small electrical perturbation will be assessed and a non-destructive test method will be developed such that CSA systems can be inspected on a routine basis and without multiple monitoring boxes. These EEC models will be developed using laboratory tests. Then, they will be calibrated and validated using further tests on prototype panel specimens with CSA systems and representing field structural elements. Further, an acceptance criteria for CSA systems will be developed. Such rational acceptance criteria will help make decisions on the quality of CSA systems in various field conditions and can be used for routine inspection and condition assessment of CSA systems in large concrete structures. This project is aiming at developing tools to enhance our ability to inspect and hence, enhance the quality of the overall concrete repair industry, especially the cathodic protection industry. |