Mechanical Sensing Properties of Embedded Smart Piezoelectric Sensor for Structural Health Monitoring of Concrete

An embedded smart piezoelectric sensor was fabricated, and the encapsulation material was prepared with cement, epoxy resin, curing agent, and improvement additives. Structural health monitoring (SHM) methods based on dynamic stress-sensing capability of piezoelectric sensor were presented. Mechanical Testing & Simulation (MTS) amplitude-scanning and frequency-scanning dynamic loadings were designed. Mechanical performance of encapsulation material, i.e., strength, Young modulus, and stress transmitting loss; the effects of different loading frequencies on output voltages; and stress sensitivities (V/MPa), were investigated. The electromechanical impedance and mechanical responses of embedded sensors with various loadings were studied in concrete. Theoretical formula indicates that output voltage is mainly related with external stress and area of Piezoelectric Lead Zirconate Titanate (PZT) ceramic. The optimized ratio of 4:2:0.5:1.6–4:2:0.5:2 is satisfactory and it can ensure optimal mechanical performance of encapsulation material. Stress sensitivities increase with the areas of PZT ceramic, and the effects of thickness on sensitivities are not obvious. The impedance response curve has left shifting tendency with the increase of dynamic cycles and loading values. The three-point bending destruction during concrete static loading can be in real-time reflected. The embedded sensors were suitable for dynamic mechanical monitoring in concrete. The excellent mechanical sensing performance exhibits great application potentials for SHM of concrete in civil engineering.