Electrical and dielectric tailoring of glass fiber-reinforced concrete using ZnO-based hybrid nanocomposites

This study investigates frequency-dependent dielectric and electrical transport properties of glass fiber-reinforced concrete (GFRC) systematically doped with ZnO-based hybrid composite (ZnO-@) nanoparticles at 1%, 2%, and 3% mass fractions. Electrical impedance spectroscopy (20 Hz-5 MHz) coupled with microstructural characterization (SEM-EDX, FTIR) and mechanical validation establishes concentration-dependent polarization mechanisms governing electromagnetic property modulation. The 2% ZnO-@ formulation exhibits optimal dielectric enhancement with maximum real permittivity (epsilon '), superior AC conductivity (100 Hz-10 kHz domain), and 100% imaginary modulus augmentation (M ''), attributed to Maxwell-Wagner-Sillars interfacial polarization at ZnO-cement matrix boundaries. Equivalent circuit modeling reveals that grain boundary resistance escalates to 5.8 M Omega at optimal doping, and constant phase element (CPE) exponent values (P = 0.77-0.84) confirming non-Debye relaxation due to hierarchical microstructural heterogeneity. The critical percolation threshold, between 2% and 3% ZnO concentration, demarcates the transition from capacitive to conductive behavior, where specimens at 3% exhibit dielectric parameter regression toward baseline values due to nanoparticle agglomeration and the formation of conductive pathways. Spectroscopic validation confirms the integration of wurtzite-phase ZnO (Zn-O: 474 cm(-)1) with preserved calcium silicate hydrate phases, while post-aging Leeb hardness measurements demonstrate 171-176% mechanical reinforcement (387-456 HLD), validating the retention of structural durability. These findings establish quantitative compositional guidelines for engineering multifunctional construction composites with tailored electromagnetic response characteristics for interference shielding, capacitive energy storage, and electromagnetically compatible innovative infrastructure applications.