Biogalvanic cathodic protection applied to a large-scale laboratory pilot concrete pier: Influence of the bioanodic surface, tidal variations and temperature

The management of corrosion in reinforced concrete (RC) structures is crucial for addressing the challenges posed by aging infrastructure, particularly in marine environments where the aggressiveness of seawater can severely impact durability. This study explores a novel approach known as BioGalvanic Cathodic Protection (BGCP), inspired by Benthic Microbial Fuel Cells, for the electrochemical maintenance of RC exposed to marine corrosion. BGCP utilizes electroactive microorganisms naturally present in marine sediments to form bioanodes on conductive materials, which provide protective electrical currents to partially submerged RC structures. A pilot study involved a 3-m-high concrete pier, which was partially immersed in natural seawater and sediments with embedded bioanodes. The current distribution from the BGCP system to the steel was monitored for over a year under various configurations, including changes in steel surface area and the number of bioanodes, while simulating tidal variations and monitoring ambient temperature. Results indicated that BGCP effectively demonstrated cathodic prevention for passive steel, with improved performance observed when multiple bioanodes were utilized. Indeed, the total current density received by the steel was in the range of [-0.2;-2 mA/m2] at all times. The current distribution varied with tidal changes, peaking at the air/water interface. A notable correlation emerged between temperature and current output, suggesting better performance at elevated temperatures. Although CP has not yet been achieved on actively corroding steel, BGCP offers significant potential for delaying corrosion initiation through the development of a selfsustaining and environmental-friendly technology.