Cathodic Polarization and Protection of Simulated Prestressed Concrete Pilings in Seawater

Abstract

Experiments were conducted to determine the effectiveness of localized cathodic polarization for reducing corrosion of simulated prestressed concrete piles containing continuous and segmented tendons exposed to seawater. Conductive rubber was used as the anode material. Corrosion of the steel was enhanced for most specimens by admixing calcium chloride (CaCl2) during concrete pouring. Specimens were polarized cathodically at constant potentials (current on) ranging from –0.72 VSCE to –1.10 VSCE. The magnitude of impressed current and its distribution along the embedded steel were monitored as a function of exposure time and level of polarization. Potential distributions for the continuous and segmented tendons were measured also. The level of cathodic polarization was assessed as a function of position along the specimens by the depolarization method and by post-test visual inspection. Protection was achieved where instant-off potentials were more negative than –0.75 VSCE. Polarization was negligible at heights > ~ 1 dm above the anode. Results were presented within the context of protecting marine pilings from corrosion.