Chloride Transport in Concrete under Flexural Loads in a Tidal Environment

A long-term exposure test of reinforced concrete (RC) beams with different flexural loads in a tidal environment has been conducted by taking the influence of time-dependent chloride diffusivity into consideration. According to the calculated apparent chloride diffusion coefficients, a chloride transport model under the coupling stresses at different depths and chloride action was established. Results indicated that the influence of flexural loads on free chloride concentrations and apparent chloride diffusion coefficients was obvious in tensile concrete zones. However, it was not a simple inhibition in compressive concrete zones. When the flexural load is less than 30% of the ultimate bearing capacity ($F_{\max }$), its effect on apparent chloride diffusion coefficients in concrete is slight. However, when 45%–60% $F_{\max }$ is exerted, a critical compressive stress can be detected. After exceeding the critical compressive stress, the chloride transport in concrete will be accelerated. Moreover, when the flexural load reaches 60% $F_{\max }$, the critical compressive stress of accelerating chloride transport, which is 5.848 MPa, that is, 20% of the cubic compressive strength ($f_{\mathrm{cu}}$), appears.