This paper discusses a new method for assessing the corrosion rate of reinforcing steel bars in concrete using the DC resistivity technique. Measurements were conducted on the reinforced concrete specimens which were made for this experiment with the different diameter of steel bars, the cover depth and compressive strength of concrete. The traditional Wenner technique (4-probe array system) was used for the concrete resistivity measurements. A DC resistivity measurement device was built for the experiment to apply the DC current perturbation. The true resistivity (ρt) and apparent resistivity (ρa) were measured using the traditional Wenner technique, and DC resistivity (ρDC-a) were also measured using the DC resistivity technique. Using these results, the corrosion rate of reinforcing steel was evaluated and compared with the results measured by the linear polarization resistance method which has been developed to direct measure the corrosion rate of reinforcing steel in concrete structure. As the results, it was shown that the corrosion rate of reinforcing steel can be evaluated quantitatively using the DC resistivity method and the corrosion rate results were similar to those measured using the linear polarization resistance method. However, it was also shown that the apparent resistivity (ρa) and DC resistivity (ρDC-a) were strongly influenced by the cover depth of concrete, the quality of concrete and the diameter of steel bars. Therefore, the further investigations for the various parameters such as the temperature and moisture contents in concrete are needed to use the DC resistivity method for evaluating the corrosion rate of steel in concrete structures in the field.
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