Long-term non-destructive assessment of reinforced concrete corrosion induced by chloride ingress and carbonation

Rebar corrosion, induced by chloride ingress and/or carbonation, is one of the most deleterious deterioration mechanisms for reinforced concrete structures. It reduces service life and entails considerable repair costs. Assessing the conditions leading to corrosion, and the progression of corrosion itself, is therefore crucial. In 2013, a series of slabs was cast using two types of cements (CEM I and CEM III), and two types of rebars (carbon steel and stainless steel). The slabs were first submitted to plain or salted water imbibition for five years and then exposed outdoors in an urban area. Over the last ten years, a series of non-destructive tests was comparatively carried out in two phases, to try to improve the accuracy of corrosion prediction in reinforced concrete. During the first 5-years phase, the progression of the imbibition was followed up by resistivity, potential and linear polarization measurements. In the second phase, the slabs were exposed to natural weathering in the Parisian suburb and the NDT measurements were taken to detect the initiation and propagation of rebars corrosion.