Macro-cell corrosion between crossed steel bars in cracked concrete

Abstract

• Macro-cell corrosion current I g included crack-induced macro-cell current I g s and current between two crossed steels I g d . • Both I g s and I g d increased in varying degrees with wider crack and the I g s / I g d ratio was always around 2. • Crack location was proved to influence the value and the direction of I g s and. I g d . To investigate the corrosion behavior of coupled crossed steel bars in cracked concrete, a study on the influence of crack width W and crack location L on the microcell and macro-cell corrosion of coupled crossed steels in cracked concrete is presented. The corrosion process of crossed steel bars in concrete specimens with crack widths of 0, 0.1, 0.2, 0.5 and 1.0 mm, respectively, were continuously monitored in an artificially created chloride environment for 26 weeks. The results showed that the corrosion of steel bars in cracked areas was much severer than that of steel bars in uncracked areas. Both microcell corrosion current ( I c o r r ) and macro-cell corrosion current ( I g ) of coupled active steel bars in a cracked area increased with the increase of the transverse crack width, and I c o r r was found to be more sensitive to the change of crack width. The I g / I c o r r ratio decreased with time, which meant that while macro-cell corrosion made a fair contribution, microcell corrosion played a dominant role in the whole corrosion period. In addition, the distance between the concrete crack and the intersection of the crossed steel bars, defined as the crack location L in the study, was proved to have a significant impact on the value and the direction of total macro-cell corrosion current I g .