A Study on the Strength Properties of Solidified Lead Contaminated Soil under Repeated Freeze and Thaw Cycles

摘要

Solidification/stabilization technology has been used extensively to reduce the mobility of heavy metal contaminants and improve the mechanical properties of the soils. Its effectiveness depends on the complex interaction among curing agent, heavy metals, and soil, which could be significantly affected by the external environment. However, the effects of long-term extreme weather conditions including freeze and thaw on the strength of the stabilized lead contaminated soils have not been investigated. This study presents a systematic investigation on the impacts of freeze-thaw (F-T) cycle on the strength properties of stabilized lead contaminated soil. The lead contaminated soil was prepared in the laboratory using a systematic strategy. Several series of tests are conducted including unconfined compression tests (UCTs) and direct shear tests on the soils subjected on the freeze-thaw cycles as well as standard cured conditions (temperature of 20 ℃ and a relative humidity of 95%). The results show that the freeze-thaw cycles have much significant impact on the strength of stabilized lead contaminated soils. After the freeze-thaw cycle tests, the unconfined compression strength, as well as the friction angle and cohesion force, were significant decrease. However, the strength loss ratio of unconfined compression depend on the binder, freeze-thaw cycles times, and extreme temperature of the freeze-thaw cycles. This study provide scientific basis for remediation of heavy metal contaminated site and prevention and treatment of heavy metal pollutant in seasonal freezing area.