Galvanic cathodic protection of steel reinforcement using metallized zinc coatings.

Corrosion of steel reinforcement in concrete bridges and parking garages due to the intrusion of chloride ions from deicing salt is a serious problem in northern climates. A number of approaches have been used in the past to mitigate steel corrosion. Cathodic protection is considered to be the only technique to slow down corrosion in salt contaminated concrete to a negligible rate. This is accomplished by either an impressed current anode or a sacrificial anode in the system. The impressed current anode system, with metallized zinc as the anode material, has been used with success on a number of bridges. The sacrificial anode system has been used on a limited number of bridges under marine environment. An impressed current system is difficult to apply to parking garages because of the thickness of concrete cover in these structures. Cover in concrete parking garages is typically much thinner than that used in bridges, and may easily cause electrical shorts between the anode and the reinforcing bar. Systems with sacrifical anodes, commonly referred to as galvanic cathodic protection systems, instead, take advantage of the reduced thickness of concrete cover, thus becoming a feasible form of protection for parking structures. The goal of this research project is to develop a sacrificial anode for cathodic protection of steel reinforcement in parking garages and bridges. Although it is too early to draw conclusions, certain trends have been reported on performance of sacrificial anode systems. So far the results indicate that the effectiveness of galvanic cathodic protection increases with decreasing the thickness of concrete cover. Salt contamination and moisture also increase the effectiveness of galvanic cathodic protection of reinforcement.