Use of Stainless Steels 316LN and Duplex 2205 in Bridge Deck Construction in North America
B. N. Neuhart
Appears on pages(s):
concrete (reinforced); construction; corrosion; reinforcement bar; steel
In the late 1990’s stainless steel has gained increased acceptance as an economically viable material for concrete reinforcement in bridge decks. Its ease of fabrication and outstanding resistance to corrosion caused by chlorides and other corrosive effluents have allowed it to be used in new bridge construction as well as rehabilitation projects. Corrosion studies have indicated that the material may have easily a life cycle of between 50 and 100 years even with heavily salted highways. Additions of nitrogen and special processing have also allowed the project designers to save weight and reduce the use of special membrane layers and other concrete additives to the bridge design. This therefore in part defrays the higher initial cost of using stainless steel reinforcement as compared to either epoxy coated or plain black steel. Before 1995, several projects in the USA, the UK and in Europe had employed 304 grade stainless as reinforcement. In North America in the last several years, higher-grade alloys of stainless such as 3 16LN and Duplex 2205 have been used more prevalently. This paper will examine the benefits of the use of these alloys. We will address why they have become increasingly accepted as well as the reasons for their selection in specific bridge projects in North America. We will also examine the specific role of moly and nitrogen as alloying elements in stainless steel rebar. A general review of corrosion mechanisms, potential problems and the physical and mechanical properties of these alloys as compared to other potential alloy selections will also be presented.