Corrosion Resistant Alloyed Steel for Low Maintenance Steel Bridges

Corrosion is a common deterioration mode for bridges in the Commonwealth of Virginia and the rest of the United States. Steel bridges are susceptible to corrosion from exposure to chlorides, either due to close proximity to a saltwater coastline or from exposure to de-icing salts. Deterioration from corrosion often results in section loss and leads to subsequent expensive repairs. Traditionally, protection systems such as painting, weathering steel, and galvanized steel have been used for steel bridges, but it is unlikely that these methods will provide a 100 year service life in aggressive environments.

Over the past decade ASTMA709 Grade 50CR, a stainless steel, has been successfully used on six bridges in the United States and has shown to be approximately 4-10 times more corrosion resistant than uncoated weathering steel. Duplex stainless steels possess increased strength and corrosion resistance compared to Grade 50CR. Since VDOT and many other transportation agencies are considering life cycle cost analysis to justify the use of alloyed steel in bridges, this paper will provide a comparison between these alloyed steels and those traditionally used in the past. This comparison includes corrosion resistance, mechanical properties, fabrication considerations, and cost considerations to demonstrate the potential benefits of using alloyed steels to produce steel bridges with a service life of 100 years.

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