Evaluating the Corrosion Level of Bare Steel Bars with Pitting Corrosionby DOFS

Abstract

Steel corrosion is one of the main causes of the deterioration of reinforced concrete structures. Localized pitting corrosion of rebar is particularly harmful, as it can severely damage mechanical properties of steel rebar including both the load and deformation capacities. Moreover, unlike uniform corrosion which can give a warning by causing extensive longitudinal cracking, pitting corrosion is often more hidden with the absence of obvious corrosion cracks. Traditional non-destructive methods based on electrochemistry may encounter large errors when estimating the pitting corrosion level in concrete; as a result, more effective methods/tools are in necessity for a timely and accurate detection of localized pitting corrosion. This study investigates the ability of distributed optical fiber sensors (DOFS) to measure pitting corrosion of steel bars, which is based on the principle that pitting corrosion causes strain localization of steel bar under tension and DOFS enable to capture the strain distribution with high spatial resolution. DOFS were attached on bare steel bars, which have mechanical notches to simulate corrosion pits, to measure the strain distribution along the notched bars under direct tension. Through experiments, the present study explores the possibility of attaching DOFS on the surface of a steel bar to monitor its pitting corrosion, and the positive results are of interest to the development of non-destructive detection method of steel pitting corrosion in concrete structures. Further quantitative analysis is required to find the correlations between the strain distribution along the notched bars and notch geometries, so that the pitting corrosion level could be assessed from the monitored DOFS strains of rebar.

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