Strength monitoring of concrete based on embedded PZT transducer and the resonant frequency

Piezoelectric lead zirconate titanate (PZT) transducer in the electromechanical impedance (EMI) technique has emerged as a potential sensing tool for structural health monitoring. In the EMI technique, PZT acts as both sensor and actuator simultaneously due to its direct and inverse piezoelectric effects. The EMI method using PZT transducers provide a new way for in-situ nondestructive testing of concrete strength development since the conventional nondestructive detection techniques have many limitations. This paper presents an experimental study on monitoring the concrete cubes´ compressive strength based on embedded PZT impedance transducers. By monitoring the PZT admittance (inversion of impedance) signals in different concrete ages the compressive strength development of concrete is predicted qualitatively. In addition, combining with the index of the resonant frequency, the correlation between concrete strength and the resonant frequency of the PZT admittance is founded. In the study, the feasibility of the EMI method based on embedded PZT transducers for monitoring the concrete strength development in early ages is verified, and it is found that the resonance frequency of the PZT admittance has a good reflection to the concrete age and the strength development of concrete.