Experimental and theoretical analyses of chloride transport in recycled concrete subjected to a cyclic drying-wetting environment

Abstract

Chloride diffusion within concrete is proved to reveal an impact on the service life of reinforced concrete structures, however, its penetration within recycled concrete has not been fully comprehended. To clarify this process, the chloride transport in recycled concrete over time was investigated through experimental and theoretical work, and the outcomes were further interpreted by microstructural analyses. The results indicate that unlike normal concrete, different chloride transport behaviors were seen in recycled concrete, which resulted from the high porosity of recycled aggregates. Meanwhile, the high porosity of recycled aggregates resulted in a quicker rise in the maximum chloride concentration over time in the drying-wetting environment, but a slower rate of decrease in the chloride diffusion coefficient. In addition, the relationship between several parameters related to chloride diffusion within recycled concrete (e.g., the chloride diffusion coefficient and the chloride binding capacity) was established. Finally, a more sophisticated model that could well describe the chloride diffusion within recycled concrete was proposed, which considered a number of key indexes.