Specifying weathering steel for bridge applications in Florida is being considered for cost savings and structural design advantages. Chloride deposition is a significant concern regarding use of uncoated weathering steel and, in Florida, coastal regions receive sea salt depositions. A606-04 steel panels (same composition as A588 weathering steel) were exposed at 30 sites in southeast Florida for periods of up to 3.5 years. The distances of the sites from the east coastline ranged from 0.1 mi to 21 mi. Generally, the corrosion rates decreased with distance from the coast, but there were interesting exceptions related to unimpeded exposure to the coastline and sulfur dioxide depositions. Results are compared to those of Townsend and Zoccola’s study of weathering steel exposures and suggestions provided for rapid site characterization for weathering steel suitability at specific locations. Corrosion rates appeared acceptable at distances greater than 2 mi from the shoreline. Direct assessments (specimen weight loss) appeared to have significant advantages over indirect, parameter measurements of chloride, sulfur dioxide and TOW (time of wetness). An advantage of direct assessment is that no environmental factor, anticipated or not, will likely be neglected. A method for making a direct assessment in an equivalent time period as indirect (ISO or ASTM) assessments is presented.
Key words: weathering steel, uncoated weathering steel, chloride, sulfur dioxide, TOW, atmospheric deposition