Determination of the distribution of electrical resistivity in reinforced concrete structures using electrical resistivity tomography

Abstract

Concrete resistivity is an important durability related material parameter. It correlates with various properties, e.g., the reinforcement corrosion rate, the water saturation degree and the porosity. The resistivity is typically determined on a structure by using the Wenner probe. Unfortunately the results can strongly be influenced by heterogeneities, e.g., reinforcement bars or inhomogeneous moisture distributions. Neglecting these effects can lead to significant misinterpretations. In order to consider these influences quantitatively the applicability of the electrical resistivity tomography (ERT) on reinforced concrete has been studied. The aim of the method is to determine the distribution of the concrete resistivity perpendicular to the concrete surface. Based on this data the spatial distribution of material properties can be derived and the influence of an inhomogeneous resistivity distribution on the corrosion rate of the reinforcement can be studied. ERT can be applied to determine the resistivity distribution of reinforced concrete within certain resolution limits. Within this work the influence of different electrode configurations and rebar positions as well as the improvement of the resolution by considering prior information are exemplarily shown. Compared to the Wenner configuration the resolution and accuracy can be improved significantly with dipole-dipole measurements.