The Kentucky Transportation Cabinet (KYTC) has maintenance oversight responsibilities for approximately 1,100 steel bridges; it also helps local governments and other entities with maintenance painting on other steel bridges. Because maintaining steel bridges is costly, Cabinet officials asked Kentucky Transportation Center (KTC) researchers to identify materials and methods that will prolong their service lives. Steel bridges are uniquely vulnerable to deterioration resulting from exposure to atmospheric conditions (e.g. moisture, ultraviolet rays) and chlorides, the latter due to the application of deicing materials. This study examines two strategies for extending service lives. First, it appraises a novel method of hot dip galvanization (HDG) and metallizing girders. Rather than dipping an entire girder in molten zinc at once, steel plates are immersed and then welded to form girders. In testing, all pieces that were coated using the method were adequately galvanized and metallized, thus establishing adequate protection against corrosion. The process can likely be scaled up and applied to larger steel pieces and girders. Next, researchers investigated whether carrying out an additional abrasive blast cleaning following power washing can reduce chloride levels. A second blast cleaning did not significantly lower chloride levels, and even led to slight increases, which may be the product of unreliable field testing or the use of recycled steel grit abrasive. Other methods of reducing chlorides should accordingly be investigated (e.g., specialized coating systems, high-performance coating systems).
Digital Object Identifier
Wells, Danny; Hopwood, Theodore; Meade, Bobby; and Palle, Sudhir, "Longer Service Life Bridge Coatings" (2020). Kentucky Transportation Center Research Report. 1738.