Durability of GFRP Bars with Different Bar Diameters

This study investigates a test concept to derive a reliable long-term strength estimation of GFRP bars in concrete environment. Using the time to failure method, test results of straight GFRP bars with different diameters were compared. To represent closely the in service-conditions of concrete structures, the examined bars were subjected to a saturated alkaline concrete environment as well as to a specified stress level till failure occurs. Thus, the experimental setup combines an alkaline resistance and creep rupture tests into one comprehensive testing. By using temperature effects as an accelerating factor, reasonable test durations were enabled. The obtained time to failure line were determined in order to extrapolate the characteristic values of the long-term strength for a service life up to 100 years. As main outcome, the study verify that the examined time to failure is affected by the bar diameter to a negligibly small extent.