The combined effects of preexposure to high temperature and alkalinity on the tensile performance of structural GFRP reinforcing\nbars are experimentally investigated. A total of 105 GFRP bar specimens are preexposed to high temperature between 120âË?Ë?C and\n200âË?Ë?C and then immersed into pH of 12.6 alkaline solution for 100, 300, and 660 days. From the test results, the elastic modulus\nobtained at 300 immersion days is almost the same as those of 660 immersion days. For all alkali immersion days considered\nin the test, the preheated specimens provide slightly lower elastic modulus than the unpreheated specimens, showing only 8%\nmaximum difference.The tensile strength decreases for all testing cases as the increase of the alkaline immersing time, regardless\nof the prehearing levels. The tensile strength of the preheated specimens is about 90% of the unpreheated specimen for 300 alkali\nimmersion days. However, after 300 alkali immersion days the tensile strengths are almost identical to each other. Such results\nindicate that the tensile strength and elastic modulus of the structural GFRP reinforcing bars are closely related to alkali immersion\ndays, not much related to the preheating levels. The specimens show a typical tensile failure around the preheated location.
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