Long‐Term Interlaminar Shear Behavior of Glass Fiber‐Reinforced Polypropylene Bars Exposed to Marine Environment

ABSTRACT Owing to the superior corrosion resistance, cost‐effectiveness, and processability, glass fiber‐reinforced polypropylene (GFRPP) bars possess extensive application potential in marine engineering. Long‐term interlaminar shear performance of GFRPP bars serves as a core index to evaluate the cooperative deformation capability of internal fiber bundles and plays a decisive role in the steady realization of their long‐term tensile properties. Therefore, to clarify the degradation mechanism and finally conduct a service life prediction analysis of GFRPP bars, this study investigated the long‐term interlaminar shear strength (ILSS) under different temperatures (25°C, 40°C, 60°C), ages (4, 8, 12 weeks), and corrosive solutions (seawater (SW) and saline‐alkaline solution (SA)). The results indicate that the ILSS of GFRPP bars decreased with prolonged corrosion, increased temperature, and enhanced alkalinity. After 12 weeks of immersion at 60°C, the ILSS retention rate was 81.3% in SW and 53.9% in SA, respectively. Initial defects induced by the pultrusion process provide primary channels for the penetration of corrosive media. The ILSS degradation exhibited a three‐stage pattern of “slow‐fast‐slow”. The ILSS retention rate prediction formulas based on the Arrhenius model showed good agreement with the experimental data ( R ² > 0.9). The predicted service lives at 5.7°C (50° N), 14°C (40° N), and 20.3°C (30° N) were 323.6, 96.4, 41.3 years (SW) and 3.9, 2.1, 1.3 years (SA), respectively. This study clarifies the long‐term ILSS data and degradation laws of GFRPP bars exposed to marine environments, providing a theoretical basis for service life assessment and safety design.