For the last 30 years, coating systems consisting of a zinc rich primer, a middle coat, and a topcoat have been used on steel bridges. The zinc primer is used because it will corrode preferentially to the steel thus preventing corrosion. The middle coat is primarily used to prevent damage, while the topcoat prevents damage to the primer and preserves the appearance of the structure. Current coating systems used on steel bridges give adequate protection from corrosion for up to 20 years. However, the appearance of current topcoats begins to degrade almost immediately, and soon, chalking, loss of gloss, and color fade can occur. This degradation is accompanied by a loss of topcoat thickness, reducing the topcoat's effectiveness in preventing corrosion. In general steel bridges will need to be repainted within 20 years. A class of coatings called fluoropolymers have been used on steel bridges in Japan for more than 30 years. These coatings have excellent resistance to the elements and offer lifetimes exceeding 60 years in some cases. The use of these materials offers substantial life cycle cost savings and reduced maintenance costs when compared to conventional coatings. This paper will compare field and laboratory test results of coatings made with fluoropolymers with more conventional coatings. Longevity of these coatings will be demonstrated by long term results from bridges in Japan. The life cycle costs of fluoropolymers will be compared to those of conventional coatings. Lastly, coating project profiles for both rail and road bridges will be reviewed.
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