Condition assessment of concrete and glass fiber reinforced polymer (GFRP) rebar after 18 years of service life

Concrete and glass fiber reinforced polymer (GFRP) bar samples from an 18-year old repair project executed on an existing dry-dock were obtained by coring the dry dock in two regions. Several destructive and non-destructive tests were performed on both materials. Testing performed on the concrete showed substantial variability and clear evidence of damage occurring over the years. Further, there were significant differences in the concrete obtained from two different regions of the dock. The concrete was carbonated and chloride from seawater had penetrated significantly into its depth. The GFRP bars showed relatively lower variability in terms of test results. Electron microscopy and horizontal shear strength results suggest that the GFRP surface of the bars had suffered some damage, whereas the core had remained unaltered. These findings regarding limited damage to the GFRP, taken together with recent advances in GFRP production technology, support the notion that concrete reinforced with GFRP bars is an attractive alternative to conventional steel reinforced concrete for marine infrastructure applications.