Abstract: Sludge soil is widely distributed in coastal areas of China. Studying the solidification of coastal sludge soil is of great significance. Research on industrial waste as the stabilizer for coastal sludge soil of shallow layer was carried out. In view of the properties of various industrial wastes, three common industrial wastes, namely, fly ash, phosphogypsum, and carbide slag, were selected as the main components of the soil stabilizer. Through mixture design experiment, the regression equations of unconfined compressive strength at age of 3 days, 7 days, and 28 days were obtained, and the optimum ratios corresponding to each age were calculated. The optimum ratio of each component of the soil stabilizer is: flyash∶phosphogypsum∶carbide slag=21.6∶26.8∶51.6. The hydration reaction process is well coordinated under the optimum ratio. The soil stabilizer under the optimum ratio was named JX18. Test results showed that the unconfined compressive strength of the sludge soil solidified by JX18 reached 413.6 kPa after 7 days, which meets the requirements of large-scale mechanical construction. The research results provide theoretical guidance for the foundation treatment of sludge soil in coastal areas.

Key words: sludge soil, industrial waste, soil stabilizer, mixture design experiment, fly ash, phosphogypsum, carbide slag