Neue innovative Diagnoseverfahren zur Dauerhaftigkeitsbewertung von Stahlbetonbauteilen

New innovative methods to assess the durability of reinforced concrete structures

Since several decades the potential mapping method is available for assessing the corrosion risk of reinforcement in concrete structures. Nowadays the assessment of the concrete quality is often based on the electrical resistivity. Unfortunately the methods typically used for determining the mentioned parameters are limited regarding their application. In cases where precast reinforced concrete segments were used (e. g. lack of electrolytic continuity) or where it is not allowed to remove the concrete cover for preparing a reinforcement connection (e. g. contaminated concrete or after repair measures) the potential mapping method can be inefficient. The determination of the electrical concrete resistivity is typically based on a four electrode reading using the Wenner setup. Due to the high conductivity of reinforcement bars or due to heterogeneous humidity distributions the Wenner approach may lead to considerable misinterpretations.
To counteract these limitations and to improve the reliability of the assessment new non-destructive methods are developed at the Institute of Building Materials Research of RWTH Aachen University. The Delta-Sensor allows, even without a reinforcement connection, the localisation of areas with a high risk of reinforcement corrosion. Furthermore a compass function allows a direct localisation of critical areas on site. By means of the Electrical Resistivity Tomography the determination of the resistivity can be improved. One of the advantages is to limit the area influenced by the reinforcement and to visualize and quantify the humidity distribution in the concrete.