Abstract
Steel in concrete in marine service corrodes actively when chloride ion concentration exceeds a critical threshold level, CT, causing passive film breakdown. There is interest in alternative or supplemental corrosion management approaches to extend structural life. One such approach is Cathodic Prevention (CPrev), based on the increase of CT when steel is polarized in the cathodic direction while still in the passive condition. This work seeks to determine the effectiveness of cathodic prevention on cracked concrete in a marine environment. Experiments use reinforced concrete blocks with controlled-width cracks placed along the length of a central reinforcing steel bar, with initial cyclic exposure to a 5% NaCl solution. Crack widths ranging from 0.01 in to 0.04 in and polarization levels ranging from -330 mV to -540 mV (SCE) were evaluated over 1 year. Results suggest that CPrev with moderate cathodic polarization levels may be of limited benefit in the presence of the lengthwise cracks. Polarization at potentials = -430 mV SCE was insufficient to prevent corrosion initiation in cracks of any of the tested sizes. Polarization at the stronger -540 mV SCE regime resulted in no corrosion initiation events for any crack size during the one-year test interval.
