Chloride transport in concrete on the side of anchorage zone under drying-wetting cycles

Abstract

The intricate interplay between multidimensional stress states complicates chloride diffusion within concrete anchorage zones, thereby compromising the reliability of durability assessments for concrete structures. Initially, one-dimensional accelerated chloride diffusion experiments were carried out in the anchorage zone of prestressed concrete T-beams under drying–wetting cycles. The effects of drying–wetting cycle duration and the stress state of the concrete in the anchorage zone on chloride distribution were then examined. Subsequently, a numerical analysis method for the convection–diffusion of chloride ions in unsaturated concrete under multidimensional stress states was established using the finite volume method (FVM). The proposed numerical approach for chloride convection–diffusion was then validated with experimental data. Finally, the effects of different parameters on the chloride ion distribution in the concrete within the spalling stress zone and on the depth of the convection zone were investigated. The results showed that prolonged drying–wetting cycles amplified chloride ingress in both the local bearing stress zone and the splitting stress zone. When the longitudinal and vertical compressive stresses were less than or equal to 0.25 and 0.13 times the applied stress level, respectively, the chloride concentration decreased by an average of 17.6 %. When the longitudinal compressive stress, the vertical tensile stress, and the shear stress in the longitudinal–vertical plane were less than or equal to 0.20, 0.26, and 0.12 times the applied stress level, respectively, the average chloride concentration increased by 31.6 %. The proposed model demonstrated an improvement in prediction accuracy of approximately 11.7 % compared with existing numerical models reported in the literature. Compared with vertical tensile stress, surface chloride concentration, and initial moisture saturation, the dry–wet cycle ratio had a smaller effect on the chloride concentration distribution.