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| Study on curing effect and micropore characteristics of chromium-polluted soil under the coupling effect of cement and quicklime |
| Received:October 19, 2017 |
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| KeyWord:hexavalent chromium pollution;unconfined compressive strength;NMR;deep depth of field;toxicity leaching;curing rate |
| Author Name | Affiliation | E-mail | | YUAN Qi | Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot 010018, China | | | SHEN Xiang-dong | Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot 010018, China | ndsxd@163.com | | XUE Hui-jun | Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot 010018, China | | | LI Gen-feng | Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot 010018, China | | | XIONG Lu | Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot 010018, China | | | ZOU Yu-xiao | Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot 010018, China | |
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| Abstract: |
| This study evaluated soils contaminated with heavy metals in terms of the solidification effect, prevention of migration of heavy metal ions, reduction of the significant drop in mechanical properties of the soil structure, and reuse in other projects, potassium dichromate(K2CrO7) was manually added to silt soil to simulate contaminated soil, based on the method of solidification stability. Unconfined compressive strength testing, leaching testing, nuclear magnetic resonance testing, and three-dimensional microtopography testing of soil samples were performed to study the curing effect and micropore characteristics of chromium-polluted soil under the coupling effect of cement and quicklime. The results were as follows:The strength of the soil increased significantly with age and reached the landfill waste standards; at the same time, the strength increased first and then stabilized or decreased with an increase in hexavalent chromium ion concentration. When the hexavalent chromium ion concentration was less than 900 mg·kg-1, the amount of quicklime had a threshold value of 4% for the strength of hardened soil. Below the threshold value, the strength of the hardened soil showed an upward trend with increasing quicklime content. The leaching toxicity decreased and satisfied standard requirements, with the pore size distribution concentrated in the range 0.1~1 μm and the structure compact. Above the threshold value, the strength of the hardened soil showed a downward trend with increasing quicklime content; the fluctuation in leaching toxicity increased as the pore size increased; and the proportion of the pore size range 1~10 μm increased, while the compactness and evenness reduced. This study provides a reference for solving environmental problems caused by leaching of six-valent chromium from contaminated soil and its permeation to groundwater. |
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