Effects of Mineral Admixtures on Chloride Diffusion in Environment-Friendly Coral Aggregate Concrete

Coral materials can replace concrete aggregates and achieve material self-sufficiency for reducing the construction costs of island projects. This paper studies the effects of different mineral admixtures on the properties of coral aggregate concrete (CAC). The chloride concentration of CAC after different erosion times is measured using the potentiometric method, and the porosity of the CAC is calculated using thermogravimetric and drying methods. The chloride concentration of the CAC presents a two-phases distribution. The peak chloride concentration followed a power function, increasing with the erosion time. The chloride diffusion coefficient of CAC is 7.9%??? 37.5% larger than that of ordinary aggregate concrete, and the addition of 15% fly ash and 5% silica fume can significantly reduce the chloride diffusion coefficient, with a maximum reduction of 45.0%. The porosity obtained via the thermogravimetric and drying methods is well correlated. The porosity has a strong negative correlation with the compressive strength and a strong positive correlation with the chloride diffusion coefficient.