Abstract: This paper presents a study of Toxicity Characteristic Leaching Procedure (TCLP) leaching characteristics of cementbased solidified/stabilized zinc contaminated kaolin. Zinc contaminated soils used in the test were artificially prepared with varying initial Zn² concentration, the cement content and the curing time. Results indicate that the pH of leachate remained stable between 10 and 12 before initial Zn² concentration reached a threshold. When the initial Zn² concentration exceeded this threshold, the pH value of leachate declined sharply below 8. There is also a threshold of initial Zn² concentration for the EC value. When the initial Zn² concentration exceeded this threshold, EC of leachate rose sharply above 7.8 mS/cm. The pH of leachate changed with initial Zn² concentration and ranged from 6.7 to 11.6. Within this range, the concentration of Ca² and Zn² decreased with the increase in pH of leachate. Ca² and Zn² ions were dominant in the leachate.

Key words: Solidification/stabilization, Zinc contaminated kaolin, TCLP, Leaching characteristics