Cathodic protection is the standard procedure available to control corrosion and the resulting concrete damage in existing reinforced concrete bridge members. Therefore, its use should be considered whenever a structure is located in a severe chloride environment. New and replacement members can be cathodically protected or prepared for cathodic protection during construction, but cathodic protection is more commonly installed as part of a rehabilitation procedure to extend the life of the structure. In principle, there are two methods for cathodic protection of bridges, sacrificial anode and impressed current.
Sacrificial anode system are, however, limited in the current and voltage that they can produce. For concrete with high resistivity, as found in atmospheric concrete, the energy output is generally not sufficient to achieve protection. In other environments, such as contact with seawater or seawater splash, protection may be achieved with the use of sacrificial anodes. Impressed current systems provide greater flexibility because the current or output can be easily adjusted. While sacrificial anode corrode, requiring periodic replacement, the service life of the anodes used for impressed current systems is usually much longer.