Durability of Extracted In-Service GFRP Bars in RC Subjected to Field Exposure

Validation of the long-term durability performance and the comprehensive development criteria/guidelines are needed for FRP systems to gain widespread acceptance throughout the engineering and civil infrastructure community in the United States. In this study, some core samples with GFRP bars were extracted from the Sierrita de la Cruz creek bridge deck in Texas, and the Southview Bridge and Walker Street Bridge in Missouri. All of the used GFRP bars were produced by Hughes Brothers Inc. Short Beam Shear (SBS) test was performed to evaluate the inter-laminar shear strength; the ignition loss of the samples, which was the resin content, was obtained by using Burn-off Test; Scanning Electron Microscope (SEM) evaluation was conducted to analyse microstructural characterisation of the FRP samples; pH measurement was also performed to monitor the possible changes in chemical behaviour of the concrete surrounding the GFRP bars. The results of SEM evaluation revealed that there was no observed degradation within the FRP bars. The inter-laminar shear strength of FRP bar (#6) was a little lower compared to that of initial control specimens. No changes were observed in the resin content and pH value of concrete. Finally, there was no evidence to illustrate FRP bar deterioration after up to 16 years of field environment exposure.