Effect of anodic polarization on the electrical properties and piezoresistive response of nano-silica modified CFRCM bundles

Nano-silica coating enhances CFRCM bonding. This study investigates the effects of anodic polarization, nano-SiO₂ coating, and matrix type (normal and seawater sea-sand mortar) on the electrical and piezoresistive behavior of carbon fabric-reinforced cementitious matrix (CFRCM) bundles, aiming to promote seawater sea-sand utilization and advance ICCP-SS-SHM tri-functional systems. Tensile tests, ICCP-accelerated polarization, and pull-out tests were conducted. Results show that during ICCP, the resistance change rate of CFRCM bundles increases slowly and linearly at low charge densities and then rises rapidly, indicating progressive conductivity degradation; the seawater sea-sand environment markedly retards this deterioration. In tensile tests, the the mean strain gauge factor of modified fiber bundles (1.56) is lower than that of unmodified ones (2.04). Resistance increases linearly in the elastic region and surges by 20%–800% at rupture. In pull-out tests, resistance exhibits a three-stage pattern: fluctuating growth, rapid growth, and slow linear growth. Initial resistance of both matrix types grows linearly with charge density, with the seawater sea-sand group showing consistently lower values. Based on experimental data, a conductivity degradation model was fitted, and the effects of nano-silica modification and anodic polarization were incorporated into an equivalent layered model. Simulation results agree well with experiments. These findings provide material-performance guidance for seawater sea-sand applications and the development of tri-functional CFRCM systems.