Effects of Coupled Immersion and Current Density on Mechanical Properties of Hybrid FRP Bars

ABSTRACT A core–shell hybrid fiber‐reinforced polymer (HFRP) bar is proposed, in which a CFRP outer layer acts as the auxiliary anode, while both the inner GFRP core and the CFRP layer provide structural reinforcement. The mechanical and electrical properties of HFRP bars were evaluated under various current densities and exposure to NaCl solution, Ca(OH) ₂ solution, and their mixture. Increasing current density elevates the feed voltage and accelerates interlaminar shear strength degradation. The bars exhibited relatively stable feed voltage and conductive behavior and maintained mechanical integrity within 2–20 A/m ² . Degradation was mainly due to resin matrix breakdown and fiber–resin interface debonding, leading to internal delamination. Ca(OH) ₂ solution had the most severe effect on properties. Even under aggressive conditions (40 A/m ² in Ca(OH) ₂ ), the bars retained 70.3% of their interlaminar shear strength. Separate service life predictions were proposed based on the degradation of mechanical properties and electrochemical performance, respectively. Within the current density range of 5–20 mA/m ² , the service lifetime dominated by electrochemical performance degradation plays a controlling role.