Galvanic Corrosion Risk of Using Galvanized A325 Bolts in Corrosion-Resistant Steel Bridges

Abstract

This experimental study was the first to evaluate the galvanic corrosion risk of using galvanized ASTM A325 Type I bolts with ASTM A1010 steel girders in the construction of A1010 steel bridges. The emerging construction of A1010 steel bridges is intended to extend the service life of bridges and reduce the need for maintenance under atmospheric corrosion attack, particularly in regions subject to severe saline exposure. However, combining high-corrosion-resistant A1010 steel with connection bolts that have a lower corrosion-resistance rating can lead to galvanic corrosion that accelerates the metal dissolution of bolts after installation and while in service. The results of this study indicate that under light saline exposure, the galvanic corrosion rate of galvanized ASTM A325 bolts used with A1010 steel was similar to the corrosion rate of A325 bolts used with ASTM A588 weathering steel. Under heavy saline exposure, however, the galvanic corrosion rate of A325 bolts was significantly higher when used with A1010 steel than when used with A588 weathering steel. Reducing the galvanic corrosion rate can be achieved by painting the joints of the steel girders, thereby reducing the cathode-to-anode area ratio. The results of this study suggest that the corrosion compatibility of the bolt and steel materials must be considered when designing corrosion-resistant A1010 steel bridges, and that the compatibility must be confirmed with an experimental validation.