Galvanic Coupling Between Carbon Steel and Stainless Steel Reinforcements

Abstract

AbstractAbstractGalvanic corrosion is a potentially major concern associated with the application of stainless steel reinforcement which is in direct (electrical) contact with carbon steel reinforcement in concrete structures. Judicious use of stainless steel rebar in both new construction and rehabilitation of older structures is a viable, cost effective option for extending service life and reducing maintenance costs. Questions, however, have arisen about the possibility of increased corrosion due to galvanic effects. This paper investigates the galvanic coupling behaviours of three different types of stainless steel and carbon steel. Tests were performed both in electrochemical cells and with specimens in concrete inside an environmental chamber. The results show that oxygen reduction on stainless steel is the rate determining factor for galvanic coupling of these two metals. It is much lower than that of passive carbon steel. As a result, the galvanic coupling of stainless steel with carbon steel will not increase the risk of corrosion of carbon steel reinforcement.Galvanic corrosion is a potentially major concern associated with the application of stainless steel reinforcement which is in direct (electrical) contact with carbon steel reinforcement in concrete structures. Judicious use of stainless steel rebar in both new construction and rehabilitation of older structures is a viable, cost effective option for extending service life and reducing maintenance costs. Questions, however, have arisen about the possibility of increased corrosion due to galvanic effects. This paper investigates the galvanic coupling behaviours of three different types of stainless steel and carbon steel. Tests were performed both in electrochemical cells and with specimens in concrete inside an environmental chamber. The results show that oxygen reduction on stainless steel is the rate determining factor for galvanic coupling of these two metals. It is much lower than that of passive carbon steel. As a result, the galvanic coupling of stainless steel with carbon steel will not increase the risk of corrosion of carbon steel reinforcement.La corrosion galvanique est un problème hypothétiquement important associé à l'application d'armature en acier inoxydable en contact (électrique) direct avec une armature en acier au carbone dans les structures en béton. L'usage judicieux de barre d'armature en acier inoxydable tant dans une nouvelle construction que dans la réhabilitation de plus vieilles structures est une option viable et rentable quant à l'extension de la durée de vie et la réduction des coûts d'entretien. Cependant, on soulève des questions concernant la possibilité d'augmenter la corrosion due aux effets galvaniques. Cet article étudie le comportement de couplage galvanique de trois types différents d'acier inoxydable et d'acier au carbone. On a effectué des essais tant en cellules électrochimiques qu'avec des échantillons dans du béton à l'intérieur d'une chambre environnementale. Les résultats montrent que la réduction d'oxygène sur l'acier inoxydable est le facteur déterminant de la vitesse pour le couplage galvanique de ces deux métaux. Elle est beaucoup plus faible que celle de l'acier au carbone passif. Comme résultat, le couplage galvanique de l'acier inoxydable avec l'acier au carbone n'augmentera pas le risque de corrosion de l'armature en acier au carbone.