Bridges

Across the globe, a huge sum is spent each year in maintaining and protecting steel infrastructure assets against corrosion. Most of the steel assets are protected using protective coatings or coating systems.

In a coating system, the first coat to be applied on the steel substrate, the primer, is generally chosen to be such as to act in galvanic or sacrificial mode which means that whereas the primer corrodes, the substrate is protected.

There are a wide variety of coatings that can be used as single coat system or standalone coatings to protect the steel substrate through galvanic action. Even though the use of single coat system is generally adopted in comparatively benign environment, galvanic coatings are in extensive use on bridge structures as primers in a multi coat system.

This paper describes the mechanism of galvanic protection and the types of coatings that are commonly used for galvanic protection, either in a multi coat coating system or as standalone coatings. It provides insight into the relative merits and limitations of the different types of such coatings. The paper is anticipated to provide specialist knowledge to the bridge community on galvanic protection of steel in a simple way so that an appropriate coating type could be selected to suit the specific need.