Performance evaluation of electro-mechanical impedance based state of health estimation of sacrificial anodes in reinforced concrete structures

Sacrificial anodes have been commonly used as a convenient and an affordable method to protect steel rebars embedded in reinforced concrete structures from corrosion, thereby extending their remaining service life. While the electro-mechanical impedance (EMI) technique has been established to be an effective technique for monitoring of concrete properties and corrosion, the effectiveness of this technique when applied to estimating state-of-health of sacrificial anodes embedded in concrete has not yet been investigated. In this work, we study the performance of EMI-based monitoring of incipient corrosion of sacrificial anodes embedded in conductive mortar and reinforced concrete. Through impressed current based accelerated corrosion experiments, we demonstrate that the root mean square deviation (RMSD) of the conductance spectra of lead zirconate titanate (PZT) transducer fitted to a sacrificial anode provides high sensitivity as a performance metric to analyze change in state-of-health of the anode. Further, analytical and FE models are developed for validating the experimental results obtained using impressed current based accelerated corrosion setup. It is found that the RMSD varies non-linearly with increasing time of application of impressed current, that can be explained adequately by the delamination dynamics of corrosion by-products and damping captured by the models. The primary advantage of this technique over conventional methods is that the degradation of the sacrificial anode in the concrete structure can be non-destructively and deterministically assessed in real time.

Automated summary

This study investigates the performance of EMI-based monitoring of sacrificial anodes embedded in conductive mortar and reinforced concrete through accelerated corrosion experiments. The RMSD is found to be a high sensitivity metric for analyzing the state-of-health of the anode, with non-linear variations explained by delamination dynamics and damping.