Corrosion behavior of coupled active and passive reinforcing steels in simulated concrete pore solution

The present study aimed to investigate the corrosion behavior of coupled active and passive steels in concrete simulated environment. Three different active-to-passive area (A/P) ratios (i.e. A/P = 1/1, 1/3, 1/20) were studied by changing the exposed area of the active steel while keeping the passive steel constant. For each group of A/P ratio, three cells were prepared: individual cell with active steel specimens, individual cell with passive steel specimens, and a coupled cell which connected active and passive steels. All specimens were immersed in a simulated concrete pore solution for 14 days. Afterwards, 3 wt% NaCl was added to the cells. Different electrochemical measurement techniques were used to assess the influence of galvanic coupling and A/P ratio on the corrosion behavior of the steel specimens. Results indicated that coupling changed the corrosion behavior of the active steel. In the case of A/P = 1/1, the corrosion was mostly observed in the form of localized corrosion, whereas in the case of A/P = 1/20, a more general and severe corrosion was observed. In addition, coupling increased the anodic and cathodic Tafel slopes which are closely related to the iron oxidation rate (i.e. corrosion rate). (C) 2019 Elsevier Ltd. All rights reserved.