This paper demonstrates an experimental study to evaluate the effects of environmental
exposures on the bond between ribbed Glass Fiber Reinforced Polymer (GFRP) reinforcing bars and
concrete. The equation recommended by ACI 440-1R-06, for the bond stress,was evaluated in this study. A total of 16 pullout samples, 12with GFRP bars and 4with steel bars, were exposed to two different harsh
environments for different periods of time. The exposed harsh environments included direct sun exposure
and cyclic splash zone sea water. The variation in the shear (bond) strengths before and after exposure was
considered as a measure of the durability of the bond between GFRP bars and concrete.Experimental results showed there is no significant difference of the bond strength between 60 and 90 days of exposures.It also showed that the empirical equation of the bond stress calculated by ACI 440-IR-06 is very conservative.