Degradation of Prestressed GFRP Bars Embedded in Seawater–Sea Sand Geopolymer Mortars under Hydrothermal Seawater Aging
Publication: Journal of Composites for Construction
Volume 28, Issue 5
Abstract
The use of glass fiber‒reinforced polymer (GFRP) bars in seawater–sea sand geopolymer mortars (SSGMs) for coastal engineering has gained significant traction because of the potential to enhance the utilization of noncorrosive GFRP reinforcements and natural resources. However, the durability of GFRP bars under the combined impact of prestressing and SSGM cover in seawater environments must be further investigated. In this study, the tensile strength (TS), interlaminar shear strength, and transverse shear strength degradation of GFRP bars were evaluated through hydrothermal seawater aging tests with immersion temperatures including room temperature, 40°C, and 60°C for 83, 180, 270, and 365 days. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were performed to investigate the degradation mechanisms of the GFRP bars after conditioning. The test findings indicated that the effect of increasing the thickness of the SSGM cover on GFRP durability was insignificant. However, without the SSGM cover, GFRP bars demonstrated superior strength retention than SSGM-covered bars after 365 days of seawater immersion because of the absence of alkali ion attack. With the application of prestressing, a greater reduction in strength retention was observed due to increased microcrack formation and penetration of OH− ions and water molecules into glass fibers. In addition, the test results were compared with the bars embedded with seawater–sea sand cement-based mortars, while the SSGM-covered GFRP bars exhibited higher TS retention under identical hydrothermal aging conditions. The high addition of ground granulated blast furnace slag in SSGM contributes to a more compact microstructure, resulting in reduced water diffusion from the outer part of the SSGM. Additionally, the strong alkali-binding capacity of the gel led to a decrease in the pH of the pore solution.
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Data Availability Statement
All data, models, and codes generated or used during the study appear in the published article.
Acknowledgments
The authors gratefully acknowledge the financial support provided by the National Natural Science Foundation of China (Grant Nos. 12372180, 12072078, and 52078141), the Science and Technology Planning Project of Guangdong Province (No. 2022A0505050077), and the Guangdong Basic and Applied Basic Research Foundation (No. 2019B151502004).
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Published In
Journal of Composites for Construction
Volume 28 • Issue 5 • October 2024
Copyright
© 2024 American Society of Civil Engineers.
History
Received: Oct 11, 2023
Accepted: Apr 16, 2024
Published online: Jul 17, 2024
Published in print: Oct 1, 2024
Discussion open until: Dec 17, 2024
ASCE Technical Topics:
- Bars (structure)
- Coastal engineering
- Coasts, oceans, ports, and waterways engineering
- Composite materials
- Engineering materials (by type)
- Fiber reinforced composites
- Fiber reinforced polymer
- Fibers
- Geomechanics
- Geotechnical engineering
- Glass fibers
- Materials engineering
- Polymer
- River and stream beds
- River engineering
- Rivers and streams
- Shoals
- Soil dynamics
- Soil mechanics
- Soil stabilization
- Structural engineering
- Structural members
- Structural systems
- Synthetic materials
- Water and water resources
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