Correlating the Evolution of Temperature and Load-Induced Damage in Concrete Using Embedded Piezoelectric Sensors

Regular monitoring of concrete structures with sensing technology has recently gained recognition as a vital factor of nondestructive evaluation (NDE). Under sensing technology, due to the cost-effectiveness and exceptional sensitivity to premature damage, piezoelectric sensors have become significantly prominent. Through the electromechanical interaction, piezoelectric Lead Zirconate Titanate (PZT) sensors facilitate in the NDE of structures. Nevertheless, as PZT is more sensitive to the temperature fluctuations, it becomes complex to interpret the data precisely. Temperature variations have the potential to distort the structural health monitoring (SHM) system and show false indications. In this work, the separate assessment of temperature and load-induced damage in the concrete has been examined to understand the temperature impacts on the PZT coupled with concrete specimen. Characterization of PZT for a stepwise temperature increase was done before testing. Over a number of temperature ranges, the electromechanical admittance (EMA) variation was assessed. Subsequently, various levels of temperature and compressive loading were applied to the PZT embedded concrete specimen. The electromechanical admittance spectrum was measured to analyze the evolution of conductance signatures throughout each stage of loading (thermal and mechanical). The variations in the equivalent dynamic parameters were analytically investigated at different levels of temperature and compressive load, and the fluctuations of the root mean squared deviation (RMSD) indices were also assessed. The effect of temperature on the conductance signatures obtained at various temperature load levels was mitigated by the use of the effective frequency shift method. The research helps the advancement of PZT sensors embedded in concrete, capable of autonomously addressing temperature dependence and assessing the impact of damage alone induced by load and temperature variations.