Research On Engineering Properties Of Soda Residue Solidified/Stabilized Heavy Mental Contaminated Soils

With the rapid development of urbanization in China, environmental pollution problems become a increasingly serious problem, especially heavy metal contamination in soil has become one of the topics people pay the most attention.Solidification and stabilization is one of the most effective methods of dealing with heavy metal contaminated sites. As a result, it is of great significance that launching the research on stabilized/solidified contaminated soil and making use of the study achievements on polluted site.This paper is based on the projects of National Natural Science Foundation of China (No.41172273) & (No.41372281). In this paper, soda residue was used as solidifying additive. Systematic tests and theoretical analyses in depth were carried out to investigate the engineering properties, leaching characters, electrical resistivity characters and micro structural changing rules of solidified contaminated soil. The main conclusions are as follows:(1) Curing time, as well as type and content of solidifying additive and heavy mental, was contrastive analyzed to study the influence on unconfined compression strength of solidified heavy mental contaminated soils. The results showed that UCS of soda residue solidified contaminated soil increased with curing time. UCS of solidified soil increased with soda residue content. Strength got worse with the increase of heavy mental ion concentration.(2) Leaching characters of soil sample with different curing time, type and content of solidifying additive and heavy mental were systematically studied by TCLP test. The results showed that heavy mental ion concentration of percolate of solidified soil decreased with curing time. For solidified lead and copper contaminated soil with different content soda residue, percolates met the environmental requirements when heavy mental ion concentration was less than 30000mg/kg.(3) The changing rules of mean resistivity, pore water resistivity and resistivity structure parameter of soda residue solidified contaminated soil were investigated. The results showed that mean resistivity, pore water resistivity of solidified soil were increased with curing time. Mean structure factor and mean size factor were increased with curing time, while anisotropy coefficient on the contrary. Mean resistivity had a positive correlation with mean resistivity and strength, and had a negative correlation with heavy mental ion concentration in percolate.(4) Adsorption characters of soda residue soil with different curing time, type and content of solidifying additive and heavy mental were analyzed. The results showed that the adsorption capacity of soda residue soils for lead ion had a linear relationship with initial concentration of heavy mental. The adsorption capacity of soda residue soils for lead ion has little effect with curing time and temperature. The pH of solution had great effect with the adsorption capacity of soda residue soils, adsorption rate got greater with the increase of pH.(5) Microstructure characters of soil with different curing time, type and content of solidifying additive and heavy mental were analyzed. The results showed that there were a large amount of hydrated products in soda residue solidified contaminated soil. The void quantity and size of hydrated products decreased with curing. The structure became compact. There were large number of microsphere structure in contaminated soil solidified with soda residue. When concentration of lead ion increased in soil, hydrated products decreased and void quantity increased, while soil became porouser.