Measurement Method for Macrocell Corrosion in Concrete Specimen using a Segmented Steel Bar

Abstract

Regarding the spatial distribution of the corrosion process it is important to distinguish between macrocells and microcells, and to measure them quantitatively when experimentally clarifying the mechanism of corrosion of steel reinforcement embedded in concrete to decide an appropriate countermeasures. Therefore, this study is aimed to develop a method for measuring macrocell and microcell currents while dividing the rebar embedded in a concrete specimen into segments. The macrocell current is defined as the current flowing between rebar segments, whereas the microcell current flows within a single segment. First, it can be confirmed that the segment length does not influence the magnitude of the total corrosion current, which is the total of the macrocell anodic current and the microcell current. In addition, it can be confirmed that the magnitude of the macrocell current increases as the segment length decreases. From the experimental results obtained, the magnitude of the macrocell anodic current or the microcell current became constant when the length of individual segments was 15 mm or less. Also, the measured value of the macrocell current flowing between the neighboring segments could evaluate the macrocell current flowing between all elements. Additionally, the amount of steel loss derived from the corrosion current using electrical measurement methods became equal to the total corrosion weight loss.