Investigations on the detectability of water intruding into bridge deck sealings by electrical resistivity measurements

Abstract

In the context of a current joint research project a monitoring system to detect leakages in bridges is implemented by using a textile reinforced concrete interlayer which consists of two carbon meshes with a spacing of 15 mm and a new developed mortar. Between the two carbon meshes the resistivity is measured with alternating current. If a leakage in the bridge deck sealing occurs and water gets into the interlayer a drop in the measured resistivity occurs and the leakage is detected. In this case repair measures can be carried out in an early stage or a preventive cathodic protection can be switched on. To assess which sizes of leakages are detectable under which boundary conditions, laboratory tests and tests on a 100 m2 outdoor demonstrator were carried out. Therefore leakages were artificially produced and the changes in the measured resistivity values were observed under different climatic conditions. Impacts such as the form of the leakages or the position of the leakages in the measuring field were varied.