Development Length of GFRP Reinforcement in Concrete Bridge Decks

This report summarizes an experimental program that investigated the development length and variability in bond of glass-fiber-reinforced-polymer (GFRP) reinforcement in concrete. The variables in the study were manufacturer (Marshall Industries Composites, Inc. [M1] and Corrosion Proof Products/Hughes Brothers [M2]), bar size (No. 5 and 6), cover (2 and 3 bar diameters), and embedment length (10 through 47 in.). Eighty-four inverted half-beam bond specimens were tested while monitoring load, loaded-end slip, free-end slip, cracking, and acoustic emissions on the embedded bar and concrete. Neither bar was recommended for immediate use as reinforcement in bridge decks. The M1 rebar exhibited cracking and splitting along the outer coating of the bar which damaged bar deformations. Additionally these bars exhibited larger COVs for bar failures with average ultimate loads below the reported manufacturer's value. The M2 rebar exhibited a smaller COV for tensile test bar failures and a similar ultimate load average when compared to the manufacturer's reported strength. However, both GFRP rebar had 47.0 in. embedment length bond tests which exhibited bar failures with ultimate loads less than the tensile test average minus two standard deviations. Keywords: Bond, GFRP Rebar, Bridge Decks