Diffusion behavior of chloride in coral aggregate concrete in marine salt-spray environment

In this study, the chloride diffusion behavior of coral aggregate concrete (CAC) in a salt-spray environment was investigated. Ten concrete groups were designed using different mix proportions, and the concrete samples were exposed to a salt-spray environment for 180 days. The effects of the aggregate type, CAC strength grade, fly ash (FA) content, and basalt fiber (BF) content on chloride ion diffusion were analyzed. The results showed that the chloride concentration of CAC was higher than that of ordinary aggregate concrete. The chloride corrosion resistance of CAC could be effectively improved by adding 30% FA or 0.1% BF to the concrete mix, and the peak chloride concentration decreases by 15.9% and 16.3%, respectively. The peak chloride concentration of concrete appeared at 3-5 mm in the concrete and exhibited a power function increase with the exposure time. In addition, a model for calculating the peak chloride concentration was established. The chloride diffusion coefficient decreased with an increase in exposure time. When the BF content was 0.1%, the chloride diffusion coefficient was the smallest. X-ray diffraction and thermogravimetric analysis were performed to analyze the erosion products, and the deterioration mechanism of the CAC in the salt-spray environment was determined.