Mechanical Properties and Microstructures of Gfrp Rebar after Long-Term Exposure to Chemical Environments

Abstract

This study describes accelerated degradation tests on glass fibre-reinforced polymer (GFRP) rebar to evaluate its long-term durability. The tests used simulated building acid, sulphate and de-icing environments. We measured the resulting reduction in the mechanical properties of the rebar and performed a microstructural degradation analysis of the rebar. The acidic environment consisted of a 0.6% acetic acid solution at a pH of 2.92, whereas the sulphate environment contained 3% sodium sulphate solution, and the de-icing environment was composed of 4% calcium chloride solution. Tensile strength tests were performed to measure the mechanical properties of the rebar after it was immersion in one of the environments for 50 to 100 days. We also measured the change in the internal pore distribution and in the shape of the rebar surface morphology using mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) technology to observe the microstructure degradation. The tests demonstrated that GFRP rebar exposed to degradation environments exhibited only slight reductions in mechanical properties with time. Areas of surface degradation were difficult to observe in the SEM analysis, and the MIP pore values were very small, indicating a dense structure. Since the durability of GFRP rebar was not adversely affected to an appreciable degree by exposure to the degradation environments, it was deemed suitable for use in concrete reinforcements.