A laboratory multisensor geophysical approach for monitoring steel rebar corrosion in concrete structures

Non-destructive monitoring methods are crucial for the management and maintenance of assets, which include reinforced concrete (RC) structures. Steel reinforcing bar (rebar) corrosion is one of the main causes of deterioration of engineered reinforced structures as it decreases their strength and serviceability. The purpose of this study was to use non-destructive geophysical techniques to detect and monitor rebar corrosion phenomena. To achieve this, several laboratory tests were performed on RC samples partially immersed in water containing a 5% of sodium chloride (NaCl) solution. Moreover, an accelerated corrosion phenomenon was produced by supplying direct current power along the rebar. Ground-penetrating radar measurements were performed on the concrete surface using 2.0 GHz centre frequency antennas, self-potential acquisitions, and electrical resistivity tomography. Even though each technique provided specific information, a data integration approach, simultaneously using different sensors, would further improve the overall quality of the diagnosis. The data set collected was used for an integrated detection approach, effective in observing the evolution of the corrosion process along the reinforcement bar. Through these laboratory results, a multisensor approach and an integrated observation proved useful for observing the evolution of corrosion phenomenon in reinforcement bars, as a consequence of the steel rebar corrosion.