Durability and microstructure degradation mechanism of FRP-seawater seasand concrete structures: A review

The wide implementation of fiber reinforced polymer (FRP) in seawater sea-sand concrete (SWSSC) structures can help solve the durability problem of infrastructure in marine environments and reduce the excessive use of fresh water resources and river sand in construction. Besides, it is conducive to reducing carbon emissions and realizing the grand goal of greener construction. This paper comprehensively summarizes the degradation law of the mechanical properties of carbon (C), glass (G), and basalt (B) FRP bars in seawater (SW) and seawater sea-sand concrete (SWSSC) environments and the bond strength and overall bearing performance of FRP-SWSSC structure. The main factors causing the degradation of the mechanical properties of FRP bars are the erosion of the internal alkaline environment and the external seawater environment of SWSSC. The microscopic test revealed the microscopic degradation mechanism of FRP bars in the SWSSC environment. It is mainly manifested in the increased moisture absorption of FRP bars after exposure to the SWSSC environment, the emergence of new chemical functional groups in the infrared spectrum, and the digestion of resin matrix and corrosion of fiber in the SEM scanning image. In addition to a comprehensive summary and evaluation of the current research results, this study also analyzes the shortcomings of the current FRP-SWSSC research stage and puts forward some valuable suggestions for the future research direction of the FRP-SWSSC structure.