Utility of Submerged Anodes for Cathodic Protection of Above-Waterline Reinforced Concrete Elements—Part 2: Bulk Magnesium Anodes

In a previous paper (Part I), the utility of Zn-submerged bulk anodes (ZnSBA) for providing cathodic protection to the above-waterline portion of a marine-reinforced concrete bridge substructure was investigated. It was determined that polarizations greater than 100 mV reached to the top of cast-in place footers (about one meter above mean tide) but decayed sharply in the columns above this. As such, it was concluded that these anodes alone did provide some protection in the splash zone, albeit not as much as when combined with either zinc thermal-spray or zincjackets. In the present investigation, similar field trials were performed using Mg-submerged bulk anodes (MgSBA), which were considered to be potentially more effective in providing protection to the above-waterline zone because of greater driving voltage. Results of these trials indicate that 100 mV depolarization was achieved in some cases to as high as 2.5 m above mean water. In addition, the substructure footer and column with MgSBA wa...