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| Curing effect and pore characteristics of cadmium contaminated soil under the action of cement-fly ash-lime |
| Received:December 05, 2016 |
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| KeyWord:cadmium pollution;cement/fly ash/lime;curing;unconfined compressive strength;leaching;porosity |
| Author Name | Affiliation | E-mail | | HAN Chao | Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Huhhot 010018, China | | | SHEN Xiang-dong | Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Huhhot 010018, China | ndsxd@163.com | | XUE Hui-jun | Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Huhhot 010018, China | | | FAN Hao-lun | Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Huhhot 010018, China | | | WANG Ren-yuan | Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Huhhot 010018, China | | | LIU Qian | Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Huhhot 010018, China | | | LIU Zheng | Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Huhhot 010018, China | |
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| Abstract: |
| The Stabilization and Solidification(S/S) method is one of the common methods currently applied in treatment of heavy metal contaminated sites. Application of S/S will not only improve the strength of the contaminated soil but also stabilize and solidify the heavy metal ions in the soil so that the same can be reused as fillings for shallow roadbed or foundation. Based on S/S-related technology and research, we added cadmium nitrate(Cd2+) into the soil to simulate the contaminated soil, and then, according to the design of the orthogonal test, the soil was mixed with curing agent composed of cement, fly ash, lime, each in different amounts, and then put under compaction molding for 7 d, 28 d, 60 d, 90 d. By studying the unconfined compressive strength, concentration of trickle-leaching heavy metals and the range and proportion of post-curing pore sizes, this paper explores how different cadmium ion concentration, mixing amount/ratio of curing agent and curing age affect the soil tested. The test results showed that with the increase of curing agent dosage and curing age, unconfined strength of the soil was significantly enhanced while heavy metal leaching rate were decreasing to a more stable state; the most influential factor on curing strength is cement content; best curing strength can be achieved with the mixing ratio of 8%(cement), 6%(fly ash), 6%(lime); in the case of 28 d solidification, the pore sizes were mainly in the range of 0.01~1 μm, indicating compact soil structure; higher proportion of pores over 10 μm in diameter will result in lower strength and higher concentration of trickle-leaching heavy metals, both of which are not conducive to using curing-hydration products for filling purposes. |
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