Abstract
The aim of this study was to investigate the combined effects of an aggressive environment and sustained load on the mechanical properties of wet lay-up fiber reinforced polymers (FRP). A total of 390 specimens, including 234 carbon fiber reinforced polymer (CFRP) specimens and 156 glass fiber reinforced polymer (GFRP) specimens, were exposed to freeze–thaw cycles, hygrothermal aging, and wet–dry cycles either in an unstressed state or loaded to about 30% or 60% of the initial ultimate load. Uniaxial tension tests were conducted on the samples after specific exposure time as well as on the control samples; and tensile properties were measured for each specimen. The results showed that the three environmental exposures, particularly hygrothermal aging, led to a significant decrease in tensile strength and elongation of the CFRP and GFRP specimens even for relatively short conditioning periods, and this decrease was markedly exacerbated by higher external loading levels. It was interesting to observe that the tensile modulus of the CFRP and GFRP specimens exhibited an excellent resistance and even appeared to increase slightly after exposure. Finally, predictive values of tensile strength based on the Arrhenius method were compared with the design values of ACI 440.2R-08 and GB 50608-2010. The results showed that both ACI 440.2R-08 and GB 50608-2010 were too conservative and significantly underestimated the tensile strength of FRP materials after an anticipated exposure period.
Highlights
In recent decades, fiber reinforced polymer (FRP) composites have been increasingly used through the wet lay-up process for strengthening deteriorated concrete structures, mainly due to their attractive properties, including excellent tensile strength, light weight, resistance to electrochemical corrosion, and ease of tailoring [1,2,3]
The results showed that both ACI 440.2R-08 and GB 50608-2010 were too conservative and significantly underestimated the tensile strength of FRP materials after an anticipated exposure period
It is crucial for a designer to consider the short-term characteristics of the materials, and the rates of deterioration of FRP composites as a function of exposure condition and time
Summary
Fiber reinforced polymer (FRP) composites have been increasingly used through the wet lay-up process for strengthening deteriorated concrete structures, mainly due to their attractive properties, including excellent tensile strength, light weight, resistance to electrochemical corrosion, and ease of tailoring [1,2,3]. FRP through the wet lay-up process has been extensively demonstrated through laboratory tests and field applications, many significant unanswered questions remain regarding its durability and the extent of service life that can be expected. FRP materials have been used successfully in the aerospace, automotive, and naval fields for many years, and have been verified as to their excellent long-term performance. Aerospace adhesives are specially made and are superior to the structural adhesives used in the civil engineering field [4]. The durability of FRP composites in unique civil engineering environments requires investigation
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