Abstract: The impermeability of cement-stabilized silty sand is significantly affected by the permeability of itself, the dosage of cement, the water-cement ratio, and other factors. How to improve the impermeability of cement-stabilized silty sand while reducing cement dosage is the key to improving the economic benefit of the project. In this study, a series of indoor permeability tests was conducted on cement-metakaolin stabilized silty sands with different cement-metakaolin ratios, initial water consumption, total cement-metakaolin contents, and curing ages. The influence of the above factors on the impermeability of cement-metakaolin stabilized silty sands were investigated, and the empirical relationships between the permeability coefficient and these factors as well as their corresponding unconfined compressive strength were discussed. The results showed that the impermeability of cement-metakaolin stabilized silty sands achieved the optimization when the ratio of cement to metakaolin was 5:1, and this mixing ratio did not change with the total cement-metakaolin content used in silty sand stabilization. The permeability coefficient of cement-metakaolin stabilized silty sands increased nonlinearly with the initial water consumption and decreased rapidly first and then slowly with the increase of the total cement-metakaolin content and curing age. Four empirical formulas for the permeability coefficient of cement-metakaolin stabilized silty sands were summarized with respect to initial water consumption, total cement-metakaolin content, curing age, and unconfined compressive strength. The results of this study can provide a theoretical reference for improving the impermeability of cement-stabilized silty sands.

Key words: silty sand, cement stabilization, metakaolin, impermeability, empirical formula