Diffusion of chloride ion in coral aggregate seawater concrete under marine environment

In this study, the diffusion law of chloride ion in coral aggregate seawater concrete (CASC) (strength = C30) was investigated in order to determine the time-varying law of chloride ion migration and penetration in CASC under two different marine environments (i.e. immersion and wet/dry cycles). By measuring the free chloride ion concentration (C-f) and apparent chloride ion concentration (C-s) in CASC at different erosion times, erosion modes and erosion depths, the chloride ion diffusion coefficient (D) was determined, and then the chloride ion diffusion model of CASC was developed. Combined with COMSOL finite element simulation software, the chloride ion transport model was verified and improved. The results show that the diffusion law of chloride ions in the two environments conforms to Fick's second law of diffusion, and there was a significant promotional effect on the diffusion of chloride ions for the CASC in the wet/dry cycles environment; the trends of C-s and D are consistent with time and conform to the power function relationship. The value of C-f calculated by using COMSOL has good correlation with the test results; the curve shape of the numerical data is consistent with the test data, and numerical error is very small, which verifies the accuracy of the model developed in this study. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study investigated the diffusion law of chloride ions in coral aggregate seawater concrete under two marine environments, confirming that the diffusion behavior conforms to Fick's second law of diffusion. Wet/dry cycles were found to have a significant promotional effect on chloride ion diffusion. The diffusion coefficient and apparent chloride ion concentration were shown to have a power function relationship with time.