Stainless Steel Reinforcement as a Replacement for Epoxy Coasted Steel in Bridge Decks

Abstract

The use of deicing salts in the United States has resulted in the steady deterioration of roadway bridge decks due to the corrosion of reinforcing steel. Since the middle 1970s, the principal corrosion protection techniques for bridge decks have involved the use of epoxy-coated reinforcement (ECR) and increased cover over the reinforcing bars. The combination has greatly lengthened the life of bridge decks, but does not represent a perfect solution. The higher cover increases the bridge dead load and the cost of construction. Epoxy-coated reinforcement adds only slightly to the cost of bridge construction, but there are a number of well-documented cases in both the field and laboratory in which poorly adhering epoxy coatings have actually increased corrosion problems, and there is evidence that all epoxy coatings will eventually be susceptible to those shortcomings. As a result of these concerns, a number of other protective measures have been developed or are under development. These include the use of denser concretes, corrosion inhibitors, and corrosion-resistant steel alloys. Among the latter are various types of stainless steel, including 2304 duplex stainless steel and stainless steel clad reinforcing bars. Based on earlier studies, stainless steel reinforcement is generally less susceptible to corrosion than conventional and epoxy-coated reinforcement, but all stainless steels do not provide the same level of protection and their superiority to ECR has not been clearly demonstrated in all cases. 2304 duplex reinforcing bars and NX-SCR™ stainless steel clad bars (the only stainless steel clad reinforcement that was commercially available in the U.S. at the initiation of this study) have not undergone the same level of testing as other solid stainless steels and prototype clad bars in environments similar to those found in bridge decks. Combined with the additional initial cost of stainless steel compared to epoxy-coated reinforcement, there is a need to quantify the costs and benefits of using stainless steel reinforcement as a replacement for epoxy-coated steel in bridge decks.