Evaluation of the Bond and Tensile Strength of GFRP Bars Exposed to Harsh Environment

Abstract

Fiber-reinforced polymers (FRP) have become one of the fastest-emerging materials to compete with conventional steel bars for use in concrete. The mechanical properties and durability of FRP materials are the main concerns that require attention. Different characteristics of FRP should be considered when estimating the service life of these polymers because they are relatively new materials in the Middle East region. By knowing the reduction in the mechanical properties of FRP bars, the durability of the bars can be predicted using data from short-term evaluation. In this thesis, the bond and tensile strengthof the bars are examined before and after exposure to various conditions in order to reveal possible deterioration. The emphasis of this research is mainly on the evaluation of glass fiber-reinforced polymer (GFRP) bars exposed to harsh environmental conditions such as the splash zones that simulate seawater immersion, high temperatures combined with high moisture, and high alkalinity. Short-term behavior of GFRP bars can be established by comparing conditioned specimens vs. unconditioned specimens. The Arrhenius equation is used to find the long-term behavior of the GFRP materials. In this study, GFRP bars were kept in different environments for three different intervals: 30, 60, and 90 days. Uniaxial and pullout tests were conducted after each exposure to measure the tensile and bond strength. The alkaline solution was the most damaging environment for the bond strength of GFRP bars with a 33.6% reduction. Tensile strength was most affected by the seawater simulation environment, which caused a 13.31% reduction. Arrhenius modeling showed that a GFRP bar required 61 days to reach 90% of its initial bond strength, and 8.5 years to reach 70% of its initial tensile strength when the bar was exposed to high temperature.