Corrosion of Steel Rebars in Anoxic Environments. Part I: Electrochemical Measurements

Abstract

The number of reinforced concrete structures subject to anoxic conditions such as offshore platforms and geological storage facilities is growing steadily. This study explored the behaviour of embedded steel reinforcement corrosion under anoxic conditions in the presence of different chloride concentrations. Corrosion rate values were obtained by three electrochemical techniques: Linear polarization resistance, electrochemical impedance spectroscopy, and chronopotenciometry. The corrosion rate ceiling observed was 0.98 µA/cm ², irrespective of the chloride content in the concrete. By means of an Evans diagram, it was possible to estimate the value of the cathodic Tafel constant ( b _c ) to be 180 mV dec ⁻¹, and the current limit yielded an i _lim value of 0.98 µA/cm ². On the other hand, the corrosion potential would lie most likely in the −900 mV _Ag/AgCl to −1000 mV _Ag/AgCl range, whilst the bounds for the most probable corrosion rate were 0.61 µA/cm ² to 0.22 µA/cm ². The experiments conducted revealed clear evidence of corrosion-induced pitting that will be assessed in subsequent research.