Corrpro's Ocean City Research subsidiary completed two research programs sponsored by the Federal Highway Administration in response to increased regulatory concern over bridge painting practices. The maintenance painting of bridges has been significantly affected by an increased awareness of the hazards to workers and the environment caused by toxins (lead and chromates) in most existing bridge coatings. Requirements for painting contractors to comply with regulations have placed an increased financial burden on federal and state Departments of Transportation (DOTs) and other bridge owners.

The purpose of the first program was to identify the elements of good painting practices to achieve optimum coating performance. The research/methodology included field and laboratory evaluation of the levels of volatile organic compounds (VOC) in the coatings tested. In general, coating manufacturers have successfully lowered the VOC content.

The study concluded that surface cleanliness, proper environmental conditions and coating application were of utmost importance in achieving good coating performance. Because of their durability, inorganic zinc and metallizing coating systems performed better than all others tested and should provide the lowest life-cycle cost when applied in conjunction with other best painting practices.

The purpose of the second program was to evaluate the benefits and limitations of painting over existing coatings. OCRC tested coating materials designed for overcoating by applying such coatings to numerous bridges across the country. Bridge overcoating is a maintenance painting option where minimal surface preparation is performed before coating over existing paint and corrosion. In the short term, this option is less expensive than coating replacement due to several factors, including mobilization of safety equipment to control the workplace environment, and the time and expense involved in surface preparation. The research concluded that overcoating is likely to provide a shorter life expectancy for a coating system as opposed to treatments using good painting practices. Overcoating is a compromise from other maintenance painting options employing more thorough surface preparations.

Final technical reports for these programs will be available from the Federal Highway Administration in early 1997. The results of this research can be used by owners of bridges and highway structures to get the most for their coating maintenance dollars.