Chloride Ion Invasive Behavior of Recycled Aggregate Concrete under Coupling Flexural Loading and Wetting-Drying Cycles

In this paper, the invasive behavior of chloride ion has been investigated under the coupling action of wetting-drying cycles and flexural load on recycled aggregate concrete (RAC) beams in sodium chloride solution. The permeation properties of chloride in RAC were studied by analyzing the content, binding capacity and diffusion coefficient of chloride. The priority of interfacial transition zone (ITZ) for chloride transport in RAC was analyzed by energy dispersive spectrometer (EDS). Additionally, the distribution of chloride content in concrete was predicted. The results indicated that the micro-pore structure, initial damage and micro-cracks provide more paths for the diffusion of chloride in the RAC. The binding capacity of chloride diminished with the incorporation of recycled coarse aggregate (RCA) and the exertion of flexural load, which increased the chloride diffusion coefficient. The correctness of Fick's second diffusion law was verified via applying it to the data processing. Furthermore, the convection and diffusion zones had the significant influence on the distribution of chloride.