Impressed Current and Galvanic Discrete Anode Cathodic Protection for Corrosion Protection of Concrete Structures

摘要

Chloride induced corrosion is recognized as a significant disease in the nation's concrete infrastructure. Government agencies and private owners are forced to contend with the rising costs of maintaining their failing structures. In response to this need, a number of electrochemical techniques have been developed over the last two decades in order to provide some relief from the normal regime of 'chip and patch' repair, or whole-scale structure replacement. This paper will provide an overview of the various corrosion mitigation techniques available and then focus on two innovative methods of using discrete anodes embedded within the concrete to provide corrosion protection to existing structures. The first of these methods uses gas vented discrete anodes to provide impressed current cathodic protection. Gas vented discrete anodes provide several key attributes which enable them to be a valuable tool for providing corrosion protection. Benefits of this anode system include; their ability to provide uniformity of protection to thick members, suitability for use on structures with low cover, structures with heavy reinforcement, and use on structures with membranes, coatings, or FRP systems. The second method to be covered is the use of embedded galvanic anodes to provide passive corrosion protection. These galvanic anodes have a lower operating potential and generally require less maintenance over their service life. These innovative discrete anodes provide the corrosion engineer with two more tools in the range of options available to cost effectively extend the life of corroding concrete structures.