Significance of macrocell currents in reinforced concrete columns partially immersed in seawater: Fid-Bau Portal

Significance of macrocell currents in reinforced concrete columns partially immersed in seawater

Lliso-Ferrando, J.R. / Soto, J. / Gasch, I. / Valcuende, M.

Highlights • Disregarding macrocell currents can lead to unrealistic corrosion estimations. • Steel mass loss by corrosion can be 8-fold higher in submerged areas (anodic areas). • Macrocell currents decrease corrosion in aerial zone close to the water surface. • The effect of macrocell currents is negligible in rebars that are in passive state. • Macrocell currents increase chloride diffusion due to a migration process.

Abstract Corrosion in reinforced concrete structures located in marine environments is probably the main cause of damage, especially in elements that are partially immersed in seawater. The moisture gradient and different chloride concentrations occur in pieces under such conditions, which give way to the formation of macrocell currents between different rebar regions. Despite being studied by several authors who have run experiments in solution or with small test specimens, the significance of macrocell currents in structures has not yet been accurately quantified. The present work studied four columns that were partially immersed in seawater for more than 1 year, when the electrical resistance of concrete and the corrosion rate were monitored. After exposure, moisture and chloride content analyses were performed, and a rebar inspection was carried out. The obtained results show that macrocell currents can increase mass loss by rebar corrosion between 3- and 8-fold. They also reveal that macrocell currents can mitigate corrosion damage in areas showing cathodic performance.