Piezo Monitoring of Concrete—A Review Paper

Monitoring of reinforced concrete (RC) structures at various stages of their life cycle remains a key to the overall maintenance strategy. Despite being the most popular construction material, RC remains vulnerable to shrinkage cracks, reinforcement corrosion, freeze–thaw, sulfate attack, etc. This adversely affects the performance of the infrastructure and in extreme cases results in the overall failure of the structure. In order to check the augmenting repair and maintenance costs, the use of non-destructive testing has gained immense popularity in the last decade. Several techniques such as fiber optics, wave propagation techniques, and vibration monitoring techniques have been proposed to detect any progressive damage taking place within concrete at different stages. Recently, the use of lead zirconate titanate (PZT) piezo patches has been used for structural health monitoring (SHM) of RC structures. This paper sheds light on the development of the piezo monitoring technique using PZT patches as a potential NDT. A detailed analysis of the electrical impedance (EI) method and wave propagation (WP) methods reported for the condition assessment using PZT patches has been described. The practical challenges associated with the use of PZT piezo patches for NDT in both EI and WP methods are addressed. Finally, the paper discusses the required areas of PZT research investigation to make it a viable NDT for RC structure.