The existence of axial and lateral compressive stress affect the diffusion of chloride ions in concrete will lead to the performance degradation of concrete structure. This paper experimentally studied the chloride diffusivity properties of uniaxial and biaxial sustained compressive stress under one-dimensional chloride solution erosion. The influence of different sustained compressive stress states on chloride ion diffusivity is evaluated by testing chloride concentration in concrete. The experiment results show that the existence of sustained compressive stress does not always inhibit the diffusion of chloride ions in concrete, and the numerical value of sustained compressive stress level can affect the diffusion law of chloride ions in concrete. It is found that the chloride concentration decreases most when the lateral compressive stress level is close to 0.15 times the compressive strength of concrete. In addition, the sustained compressive stress has a significant effect on chloride ion diffusion of concrete with high water/cement ratio. Then, the chloride diffusion coefficient model under uniaxial and biaxial sustained compressive stress is established based on the apparent chloride diffusion coefficient. Finally, the results demonstrate that the chloride diffusion coefficient model is reasonable and feasible by comparing the experimental data in the opening literature with the calculated values from the developed model.

Existing studies on chloride ion transport in concrete under compressive load had rarely incorporated the influence of the dry–wet time ratio, even though this ratio was a key factor affecting chloride penetration in coastal concrete structures subjected to periodic drying–wetting cycles. This study was therefore motivated to fill this gap and to provide more reliable theoretical support for the durability assessment of such engineering structures. A series of accelerated chloride ion penetration experiments was conducted on concrete under compressive load with different dry–wet time ratios. The effects of the dry–wet time ratio, compressive stress level, and exposure environment on chloride ion transport in concrete were analyzed. A chloride ion diffusion coefficient model that accounted for both the dry–wet time ratio and the compressive stress level was then established and validated. The results showed that the enhancing effect of the dry–wet time ratio on chloride ion transport became significant under relatively high compressive stress. When the dry–wet time ratio was 7:1, the convection zone depths of concrete specimens under no stress and compressive stress were both 5 mm. Moreover, when the compressive stress level was 0.5 times the compressive strength and the dry–wet time ratio was 7:1, the chloride concentration of the specimens increased by an average of 756.4% compared with that under natural immersion.