Experimental and Comparative Study on Compressive Strength of GFRP Rebars

Glass fiber-reinforced polymer (GFRP) rebars are a more corrosion resistance alternative over steel rebars for concrete structures in coastal areas and cold climate regions such as Canada. However, an existing challenge for the implementation of GFRP rebars is their brittle nature. In particular, for the use of GFRP rebars as the main longitudinal rebars in columns, Canadian Standards Association (CSA) and American Concrete Institute (ACI) ignore or underestimate their contribution. Significant variations in test results and lack of data in this area are the main reasons for making this conservative decision. However, the new trend of CSA is toward considering the participation of GFRP rebars in compression thanks to the experimental efforts that have been taken so far. Therefore, further investigation and test data are required on GFRP rebars and GFRP-reinforced concrete (RC) columns to improve knowledge to completely overcome the lack of confidence in the contribution of GFRP rebars in compression. In this study, previous research efforts on the compressive behavior of GFRP rebars are reviewed. Consequently, fifteen test specimens of GFRP rebars were prepared and tested using the only standard test method that is proposed for rigid plastics by ASTM D695-15. Although test methods have been introduced recently for testing the GFRP rebars in compression, some researchers still prefer using the only available ASTM method. The aim is to obtain a broader understanding of the limitations and the range of outputs compared to the literature. As a result of the tests, a compressive to tensile strength ratio of about 44% on average was obtained. The failure of the rebars mostly started at the ends which are most susceptible to damage. Some specimens prematurely failed due to very local stress concentrations while in the others longitudinal splitting was the observed mode of failure.