Progressive monitoring of temperature and stress induced damages in fiber-reinforced cementitious composites through electrical admittance response of coupled piezoelectric sensors

Monitoring of temperature-induced and compressive stress-induced degradation of temperature-treated fiber-reinforced cementitious composites (FRCC) were investigated through lead–zirconate–titanate (PZT) sensors. A comparative analysis of the fibrous and non-fibrous cementitious composites was presented by including polypropylene (PP) and polyethylene (PE) fibers. The analysis was performed on the electrical admittance (EA) response of surface-mounted (SM) and embedded (EM) sensors for cement composite specimens subjected to cyclic temperature loading–unloading and compressive stresses. Shifts in the resonance modes, along with the damage index, root mean squared deviation (RMSD), were examined for the quantitative analysis. A progressive rise in the peak amplitude of both the sensors was observed, indicative of the distributed temperature-induced damage. A reduction in the frequency of both the PZTs with each temperature cycle was observed, indicative of the loss of the specimen’s stiffness. Subsequently, the damping effect caused by the compression-induced damage resulted in a shift in the amplitude and frequency. The loss of moisture and an increase in porosity of the cement matrix caused by temperature changes, coupled with fluctuations in fiber characteristics, were evident in the electromechanical impedance response of the PZT sensors. An effective frequency shift (EFS) method was utilized for the mitigation of temperature effects. The sensitivity of PZT sensors to the temperature induced damages in the FRCC was demonstrated.