Abstract：In order to evaluate the shear strength and leaching characteristics of the solidified composite heavy metal contaminated soil after long-term freeze-thaw cycles (up to 90days (times)), triaxial compression test and toxicity characteristic leaching procedure test were carried out on the lead-zinc-cadmium composite heavy metal contaminated soil after solidification/stabilization with composite curing agent of cement, quicklime and fly ash. The results show that the angle of internal friction only increased significantly to 3 freeze-thaw cycles, and the increase rated was as high as 96.3%; while the overall trend of cohesion continued to decline by 30 freeze-thaw cycles, and there was no significant change afterwards, and the final decline rate reached 54.23%; the leaching concentration of Pb2+, Zn2+, Cd2+, and the EC value of the extract is proportional to the number of freeze-thaw cycles; the pH value of the extract decreases after long-term freeze-thaw cycles. And through scanning electron microscopy, we further explored the degradation mechanism of the shear strength and leaching characteristics of solidified contaminated soil under long-term freeze-thaw cycles. The results show that a large amount of delayed ettringite is formed in the solidified soil at the end of the freeze-thaw cycle, and its expansion during the formation process is the main reason for the loss of shear strength and the increase of heavy metal leaching concentration.
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WANG yao, YANG Zhong-ping, ZHOU Yang, CHANG Jia-zhuo, LI Deng-hua, LUO Jun. Shear strength and leaching characteristics of solidified lead-zinc-cadmium composite heavy metal contaminated soil under long-term freeze-thaw cycles. CHINA ENVIRONMENTAL SCIENCECE, 2022, 42(7): 3276-3284.
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