Protection of concrete structures in immersion service from biological fouling with silicone-based coatings

The unrestricted growth of aquatic organisms (macrofouling) on surfaces of submerged concrete intake structures and circulating water systems of power plants is a significant problem in the industry, resulting in substantial operating and maintenance costs. Traditional chemical approaches to control the problem are under increasing legislative scrutiny, and regulatory actions that limit chemical discharge and require toxic use reduction may also further curtail the use of biocides. Nontoxic, silicon-based foul release coating systems appear to be an especially attractive solution to conventional treatment methods; however, criteria for coating selection and successful application are not well defined due to the relatively limited use of this technology in the industry. This article presents case histories from two utilities, reviews their testing and coating selection strategies, and discusses the application difficulties with coating-aged concrete surfaces in immersion service