| 原奇,申向东,薛慧君,李根峰,熊路,邹欲晓.水泥-生石灰对铬污染土固化效果及微观孔隙特征的影响[J].农业环境科学学报,2018,37(6):1141-1148. |
| 水泥-生石灰对铬污染土固化效果及微观孔隙特征的影响 |
| Study on curing effect and micropore characteristics of chromium-polluted soil under the coupling effect of cement and quicklime |
| 投稿时间：2017-10-19 |
| DOI：10.11654/jaes.2017-1418 |
| 中文关键词: 六价铬污染 无侧限抗压强度 核磁共振 超景深 毒性浸出 固化率 |
| 英文关键词: hexavalent chromium pollution unconfined compressive strength NMR deep depth of field toxicity leaching curing rate |
| 基金项目:国家自然科学基金项目（51569021，51769025） |
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| 摘要点击次数: 1910 |
| 全文下载次数: 1854 |
| 中文摘要: |
| 为评价水泥和生石灰对铬污染土壤的固化效果及固化土在工程中再利用的可行性，采用固化稳定法进行六价铬污染土壤的修复试验，将重铬酸钾（K2CrO7）人工添加至粉砂土以模拟污染土，通过无侧限抗压强度、浸出毒性、核磁共振孔隙和微观三维形貌试验，研究水泥和生石灰对铬污染土的固化效果及其微观孔隙特征。结果表明：固化土强度随龄期增加而显著增加，且达到废弃物的填埋标准，同时随六价铬离子浓度增大强度先增加后稳定或减少；六价铬离子浓度小于900 mg·kg-1时，生石灰掺量对于固化土强度存在阈值为4%，低于4%时随着生石灰掺量增加强度呈上升趋势，浸出毒性降低且达到浸出标准，同时0.1~1 μm孔隙占比最高，结构致密；高于4%时随着生石灰掺量增加强度呈下降趋势，浸出毒性波动变化，1~10 μm的大孔径增多，结构致密性差，平整度降低。研究表明，掺入合适比例的水泥和生石灰对铬污染土有较好的固化效果，可防控受污染土壤中六价铬浸出和渗透到地下水带来的环境问题。 |
| 英文摘要: |
| 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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