Optimizing Coated PZT Sensors for Structural Health Monitoring in Hybrid Fibre-Reinforced Concrete Beams

This study investigates the integration of coated piezoelectric (PZT) sensors in hybrid fibre-reinforced concrete (HFRC) beams to assess their potential in structural health monitoring (SHM). The research focuses on the role of various sensor coatings—nitrocellulose-based nail polish (NP), quick-set epoxy resin (RE), and epoxy putty (EG)—and explores the impact of coating thicknesses on sensor performance. The HFRC beams, reinforced with glass and polypropylene fibres, were embedded with coated and uncoated sensors and evaluated for their impedance properties across curing periods and under mechanical stress. Results indicate that NP and RE coatings provided superior electrical insulation and signal stability compared to EG, which exhibited higher conductance and reduced sensitivity. Thicker coatings enhanced durability but diminished the ability to detect fine structural changes. Optimal performance was achieved with 2–2.5 mm coatings, offering a balance between sensitivity and sensor protection. Experimental analyses revealed distinct trends in frequency-conductance behavior before and after damage, validating the efficacy of PZT sensors in identifying fractures. The findings underscore the potential of integrating advanced sensor technology with optimized coatings in HFRC beams for real-time damage detection and enhanced durability. This work contributes to advancing SHM systems, promoting safer and longer-lasting concrete infrastructure. © The Author(s), under exclusive licence to Shiraz University 2025.