Corrosion performance of conventional (ASTM A615) and low-alloy (ASTM A706) reinforcing bars embedded in concrete and exposed to chloride environments

Conventional reinforcing steel is used in the majority of reinforced concrete structures. In general, steel reinforcement meeting ASTM A615 specifications has been the predominant reinforcement used for these structures. Low-alloy reinforcing steel (ASTM A706) was developed and is being marketed to improve ductility and weldability deficiencies associated with the ASTM A615 reinforcement. Several State Highway Agencies have adopted the use of these low-alloy reinforcing steels. Limited research has been performed on the corrosion characteristics of the steel reinforcement meeting ASTM A706 specifications. This paper presents results from a laboratory study on the critical chloride threshold, macrocell corrosion rates, and mass loss testing for ASTM A706 and ASTM A615 reinforcing steels embedded in concrete and exposed to chloride solution. Results from this study indicate that ASTM A706 reinforcing steel exhibits lower critical chloride threshold levels and higher corrosion rates than ASTM A615 reinforcing steel when embedded in cementitious materials.