Tensile behavior of TRC under coupled chloride exposure and impressed current: Deterioration mechanisms and strength prediction

To reveal the evolution law and deterioration mechanism of the uniaxial tensile behavior of TRC under the coupled effect of chloride exposure and impressed current, this study adopted a combined approach of uniaxial tensile tests, microstructural characterization, and semi-empirical analysis. The effects of chloride concentration, charge density, and textile type on the mechanical performance were investigated. The results show that under non-electrified conditions, the first cracking load of the specimen first increases and then decreases with increasing chloride concentration, while the peak load exhibits little change. Under impressed current, the load-displacement curve changes from a four stage pattern to a two stage pattern, the peak load and peak deformation decrease significantly, and the crack pattern shifts from multiple cracking to a single major crack, showing obvious brittle failure characteristics. As the charge density increased, the initial tensile stiffness of the specimens continuously decreased, and the peak load was significantly reduced. SEM observations showed that, at a relatively low charge density, the fine-grained concrete matrix remained relatively dense and the surfaces of the carbon fiber bundles were generally intact. With increasing charge density, matrix cracking and surface damage to the carbon fiber bundles became progressively more pronounced. In addition, neither changing the textile configuration nor applying impregnation treatment effectively improved the tensile performance of the specimens under electrified conditions. On this basis, a residual strength coefficient was introduced to develop preliminary semi-empirical relationships for estimating the uniaxial tensile load-bearing capacity of TRC under chloride exposure with and without impressed current. The proposed relationships provide a reasonable fit to the experimental data within the tested ranges. The findings provide experimental evidence and a preliminary basis for evaluating the mechanical performance of TRC intended for potential ICCP anode applications.