Analysis on influencing factors of cadmium contaminated soil solidified by alkali-activated fly ash-slag

被引：0
|
作者：
Wang H. [1 ]
Zhu Z. [1 ]
Pu S. [1 ]
Huo W. [1 ]
Song W. [1 ]
Wan Y. [1 ]
机构：
[1] School of Transportation, Southeast University, Nanjing
来源：
Dongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Southeast University (Natural Science Edition) | 2021年 / 51卷 / 06期
关键词：
Alkali-activated fly ash-slag; Cadmium contaminated soil; Leaching properties; Microstructure; Solidification/stabilization; Unconfined compressive strength;
D O I：
10.3969/j.issn.1001-0505.2021.06.015
中图分类号：
学科分类号：
摘要：
To study the effects of liquid-solid ratio and slag content on the strength and leaching characteristics of alkali-activated fly ash-slag solidified cadmium contaminated soil, taking slag partially replacing fly ash as the cementitious powder, NaOH and Na2SiO3 solution as the alkali activator, the changes of strength, leached Cd2+concentration, pH of cadmium contaminated soil solidified by alkali-activated fly ash-slag were analyzed by unconfined compressive strength, toxic leaching and pH tests. The micro-characteristics of solidified contaminated soil were studied based on the test results of scanning electron microscopy-energy dispersive spectroscope(SEM-EDS), X-ray diffraction(XRD) and mercury intrusion porosimetry(MIP). The results show that the strength of solidified contaminated soil decreases sharply at first and then remains stable with the increase of liquid-solid ratio, and increases slowly with the increase of slag content. The leached Cd2+concentration is less than 0.01 mg/L when the liquid-solid mass ratio is 0.3 to 0.4, but increases sharply when the liquid-solid mass ratio exceeds 0.4. The leached Cd2+concentration decreases with the increase of the slag content. The main immobilization mechanism of Cd2+ by alkali-activated fly ash-slag binder is the formation of Cd(OH)2. The addition of Cd2+ will reduce the alkalinity of the system and hinder the alkali excited reaction. The volume fraction of pores with pore size between 1 μm and 10 μm and lager than 10 μm increases with the increase of the liquid-solid ratio, which is related to the increase of the initial water content of the sample. © 2021, Editorial Department of Journal of Southeast University. All right reserved.
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页码：1025 / 1032
页数：7
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