Effect of ICCP on conductivity properties of carbon fiber bundles and CFRCM

The effectiveness of carbon fabric reinforced cementitious matrix (CFRCM) in impressed current cathodic protection (ICCP) and structural strengthening (SS) of reinforced concrete (RC) structures has been verified. Meanwhile, due to the piezoresistive effect of carbon fibers, CFRCM has been developed as a self-monitoring sensor for structural health monitoring (SHM). However, the conductivity properties of CFRCM and carbon fiber under ICCP will be subject to performance degradation due to anodic reaction, which may have adverse effects on their role in SHM, and the degradation in seawater sea-sand (chlorine-containing environments) is still unknown. In this study, simulated ICCP tests were carried out on carbon fiber bundles in different solution environments and mortar environments to investigate the influences and mechanisms of different ICCP current densities, electrification durations, electrification environments, fiber lengths, and mortar types on conductivity properties of carbon fiber bundles and CFRCM. The prediction models for resistance were established based on a large number of experimental measurements. The results show that changes in resistance of carbon fiber bundles and CFRCM under ICCP exhibit two-stage characteristics of linear growth and rapid growth. The presence of chloride ions in seawater sea-sand environments can share polarization currents, reduce electrode potential, and slow down carbon fiber degradation. The degradation rates of carbon fiber bundles under four electrification environments, from fast to slow, are as follows: normal mortar, seawater sea-sand mortar, saturated Ca(OH)₂ solution, and saturated Ca(OH)₂ solution prepared with seawater. This study aims to promote the development of CFRCM materials with the multifunctional properties of ICCP-SS and SHM, and to achieve rational utilization of seawater and sea-sand.