Durability performance and service life of CFCC tendons exposed to elevated temperature and alkaline environment

This paper presents the physical, mechanical, and durability characterization of Tokyo Rope carbon fiber composite cables (CFCCs). Specimens were exposed to and alkaline solution (12.8 pH) for 1,000, 3,000, 5,000, and 7,000 h at different elevated exposure temperatures (22, 40, 50, and 60°C) to yield a simulated acceleration of the effect of a concrete environment. The durability performance of the Tokyo Rope CFCC tendons was assessed by conducting tensile tests on the specimens after different exposure periods. In addition, the microstructure of the CFCCs - both conditioned and unconditioned specimens - was investigated with scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) to assess any changes or degradation. The preexposure and postexposure tensile strengths of the conditioned and unconditioned specimens were used for long-term behavior/performance predictions based on the Arrhenius theory. The test results revealed that the average tensile strength retentions of the conditioned CFCCs could be affected by accelerated time and temperature. According to the predictions, even after a service life of 100 years, the tensile strength retention of the tested Tokyo Rope CFCC tendons would still be more than 90% at mean annual temperatures of 50°C (the mean annual temperature and the marine environment of the Middle East and warm regions) and 10°C (mean average temperature of northern regions)