Experimental research on durability of solidified lead-contaminated soils under wetting-drying cycles

Kaolin and bentonite, two clay minerals are mixed with sand respectively, and then mixed with lead nitrate to produce artificial lead-contaminated soils. Cement and lime are used to solidify the artificial lead-contaminated soils respectively. The samples are made using the compaction method. The relative mass loss, cumulative mass loss rate and unconfined compression strength (UCS) of samples after wetting-drying cycle tests are recorded, in order to evaluate the wetting-drying cycles durability of the solidified lead-contaminated soil. The results show that the wetting-drying cycles durability of samples in this study all meet the requirement; wetting-drying cycles durability of bentonite mixed soil is worse than kaolin mixed soil; cement solidified soil performs better than lime solidified soil in terms of wetting-drying cycles durability; admixing 8 000 mg/kg lead slightly leads to an enhancement of wetting-drying durability of stabilized soils. Water content is a key parameter to immobilize heavy metal in cement or lime, and enough water should be available for hydration, hydrolysis, pozzolanic and carbonization reactions of cement or lime.