Electrochemical Characterization of Steel Bridge Welds under Simulated Durability Test

Abstract

Ever increasingly, corrosion-induced steel bridge deterioration, particularly near or at the welded joints, has led to a huge economic burden in the United States. There is, however, no sufficient information about weldment corrosion in steel bridges, which has hindered the application of appropriate corrosion mitigation. This study is to better understand corrosion behavior of steel bridge welds. Investigation of weldment corrosion of commonly used bridge steels, the low-carbon iron steel, and weathering steel, was performed using four electrochemical tests under simulated corrosive environments. Two coating systems, organic zinc-rich three-coat system and one-coat calcium sulfonate alkyd (CSA), were deposited to the samples to determine their performance at weldment. Results revealed that bridge welds exhibit higher corrosion initiation over base metals, regardless of types of steel or coating. In addition, the weathering steel shows the higher resistance to corrosion initiation (twice as high) in welded area as compared to the low-carbon iron steel. Moreover, the protective coating can effectively delay the corrosion initiation at the welds, thus enhancing the corrosion resistance of bridge welds.