| Stabilization/solidification technology is widely and successfully applied forremediation of heavy metal contaminated soils around the world. While in aggressiveion-rich groundwater environment, the secondary contamination due to the existence ofaggressive ions will significantly influence the characteristics of the remediated sites,including the microstructure, strength and leaching characteristics of the heavy metalions. Therefore, understanding the remediation mechanism of heavy metal contaminatedsoil and the reactions between the corrosive ions and the soil particles can help thescholars and engineers with prevention of secondary contamination. The researchconducted in this field will also have a great benefits on protecting human life andhealth, maintaining the ecological balance of the land resources and environment andguarantying engineering construction safety.Based on the project supported by National Natural Science Foundation (No.41172273), the research conducted in this paper aims to investigate the characteristics ofstrength, compressibility, heavy metal leaching and microstructure under aggressiveion-rich groundwater conditions. The main findings obtained from the tests are shownas follows:(1) According to comprehensive laboratory test, increasing the NaCl concentrationcauses that the strength of specimens reduces and compressibility magnifies.Short-time(7days) immersion can decrease the strength, enlarge the compressibilityand increase the permeability of the specimens.And compared with the specimensimmersed for a short time,the strength of long-time immersion specimensincreases,compressibility decreases and permeability also reduces. The influence of typeand content of the solidified agent on corrosion resistance ability was also compared;Then, the engineering characteristics of the solidified soils after contamination bydifferent heavy metal ions and concentrations were investigated deeply.(2) Based on triaxial stress-strain test, this paper investigates the deformationcharacteristics of the solidified heavy metal contaminated soils under erosiveenvironment. The test results show that the deformation of the samples includes threephases:â‘ Elastic deformation;â‘¡Plastic yield deformation;â‘¢failure-deformation.Thedeformation characteristics of solidified heavy metal contaminated soils under differenterosive environments was obtained.(3) According to TCLP leaching test results, the leaching characteristics of solidified soil after erosion was investigated. The remediation mechanisms of Pb2+and Cr3+contaminated soils were obtained by analyzing the influence of NaCl concentration,soaking time, solidified agent type, as well as the type of heavy metal ions on leachingcharacteristics. The results show that the curing mechanism of Pb2+isadsorption,precipitation and physical encapsulation,and Cr3+is chemical crystallizationand metathesis.(4) The Scanning Electron Microscopy (SEM) technology was used to study thevariation of microstructure of solidified heavy metal contaminated soils during erosionprocesses. The results show that NaCl concentration, soaking time, solidified agent type,as well as the type and concentration of heavy metal ions have significantly influence onhydration processes,cementation between soil particles and pore volume. |
