Depassivation of steel reinforcement in case of pitting corrosion: detection techniques for laboratory studies

Methods for service life prediction of reinforced concrete structures exposed to chloride-bearing environments require the knowledge, amongst other parameters, of the chloride threshold for pitting corrosion initiation (Clth). Nowadays, although the main factors influencing the chloride threshold are well known, it is often difficult to quantify a value of the chloride threshold, partly because of its intrinsic high variability, and partly because of the different tests methods that have been used to measure it. All the experimental tests rely on the detection of steel depassivation and simultaneous measurement of chloride content or steel potential. This paper deals with the methods that can be used to detect steel depassivation in relation with the determination of the chloride threshold. Tests in concrete-pore-simulating solutions as well as tests in concrete will be considered, and advantages and limitations will be discussed.