Electrical resistivity testing for as-built concrete performance assessment of chloride penetration resistance

The electrical resistivity of concrete can provide information about its transport properties, which is relevant for durability performance. For example, resistivity is inversely proportional to chloride diffusion, at least within similar concrete compositions. A methodology is proposed for on-site assessment of concrete cover resistance against chloride penetration, based on on-site resistivity testing. As such, resistivity testing can extend existing service life approaches to assessing on site performance. For example, the Dutch Guideline for Service life design of structural concrete (in chloride contaminated environment) is based on chloride transport testing in the prequalification stage and production control by resistivity testing of wet-cured control cubes. Adding on-site resistivity testing would extend this approach with testing for as-built quality of the concrete cover. Applying this method requires that corrections are made for the effects of reinforcing bars, inhomogeneities due to drying out and resistivity increase due to cement hydration. A correction for the presence of reinforcement can be obtained by numerical modelling based on combined (simultaneous) cover depth and resistivity measurements. Effects of hydration and drying out can be accounted for using long-term resistivity data for concrete with different cement types and water/cement ratios in different moisture conditions.
Structural Engineering
Civil Engineering and Geosciences