Fundamental study on cotton-like fiber acting as electrolyte carriers in the sacrificial anode cathodic protection system for closed-section steel structures under atmospheric environments

In the pursuit of sacrificial anode cathodic protection (SACP) for closed-section steel structures exposed to atmospheric conditions, a cotton-like fiber serves as the electrolyte carrier. The efficacy of this approach was validated through assessments of water absorption, retention, electrochemical properties, and SACP trials. The cotton-like fiber exhibited notable hydrophilic characteristics, absorbing nearly seven times its weight of the electrolyte and retaining over 50% of its maximum water absorption capacity after 15 days. Furthermore, the ionic conductivity of the fiber, when fully saturated with 0.1 wt% NaCl aq, was nearly twice that of the same concentration solution without fibers, diminishing as the electrolyte content decreased. Additionally, the open-circuit potential (OCP) of the Al-3Zn sacrificial anode was approximately −0.2 V relative to steel. Moreover, Nyquist plots revealed that electrodes in fibers were more resistant to dissolution compared to those in 0.1 wt% NaCl aq. In the SACP tests, the combination of cotton-like fibers with the Al-3Zn anode exhibited a protective performance for steel members, as assessed by the current density, instant-off potential, and steel surface conditions.