Hybrid anode concrete corrosion protection – independent study

Abstract

This study was the first of its kind to investigate the long-term performance of hybrid anode systems in reinforced concrete as part of a holistic approach to corrosion risk assessment. An independent appraisal of the site performance of hybrid anode corrosion protection systems (UK invention disclosed in Patent GB2426008B) was conducted on six bridge structures in 2014. The aim of the study was to investigate the effectiveness of current design approaches in meeting the residual service life when the anodes are operating in the galvanic phase. This was achieved by analysing data on the general condition of the structures, studying the ongoing performance of the installed hybrid anodes and assessing the overall corrosion risk. It was found that the six structures were generally in good condition, with low associated corrosion risk in areas protected by the hybrid anode systems. This is a positive finding for the wider implementation of hybrid anode systems as an alternative corrosion management technique. The reinforcement in the protected areas remained predominately in a passive condition, with calculated corrosion rates below the ISO 12696:2012 recommended threshold of 2 mA/m2. Recommendations regarding design are provided in order to improve the redundancy, functionality and robustness of hybrid anode systems.