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Geomechanics and Engineering Volume 36, Number 6, March25 2024 , pages 619-629 DOI: https://doi.org/10.12989/gae.2024.36.6.619 |
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Study on mechanical properties of phosphate tailings modified clay as subgrade filler |
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Xiaoqing Zhao, Tianfeng Yang, Zhongling Zong, Teng Liang,
Zeyu Shen, Jiawei Li and Gui Zhao
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| Abstract | ||
| To improve the utilization rate of phosphate tailings (PTs) and widen the sources of subgrade filler, the PTs is employed to modify clay, forming a PTs modified clay, applied in the subgrade. Accordingly, the environmental friendliness of PTs was investigated. Subsequently, an optimal proportion was determined through compaction and California Bearing Ratio (CBR) experiments. Afterward, the stability of mixture with the optimal proportion was further evaluated through the water stability and dry-wet stability experiments. Finally, via the gradation and microstructure experiments, the strength mechanism of PTs modified clay was analyzed. The results show that the PTs were classified in the non-hazardous solid wastes, belonging to Class A building materials. With the increase of PTs content and the decrease of clay content, the optimum water content and the swelling degree gradually decrease, while the maximum dry density and CBR first increase and then decrease, reaching their peak value at 50% PTs content, which is the optimal proportion. The resilient modulus of PTs modified clay at the optimal proportion reaches 110.2 MPa. The water stability coefficient becomes stable after soaking for 4 days, while the dry-wet stability coefficient decreases with the increase of cycles and tends to be stable after 8 cycles. Under the long-term action, the dry-wet change has a greater adverse impact than continuous soaking. The analysis demonstrates that the better strength mainly comes from the skeleton role of PTs and the cementation of clay. The systematic laboratory test results and economic analysis collectively provide data evidence for the advantages of PTs modified clay as a subgrade filler. | ||
| Key Words | ||
| clay; economic efficiency; environment-friendly; mechanical property; mechanism; phosphate tailings | ||
| Address | ||
| Xiaoqing Zhao, Zhongling Zong and Jiawei Li: School of Civil and Ocean Engineering, Jiangsu Ocean University, Jiangsu 222005, China; Marine Resources Development Institute of Jiangsu (Lianyungang), Jiangsu 222005, China; Jiangsu Ocean Engineering Research Center for Intelligent Infrastructure Construction, Jiangsu 222005, China Tianfeng Yang, Teng Liang and Zeyu Shen: School of Civil and Ocean Engineering, Jiangsu Ocean University, Jiangsu 222005, China Gui Zhao: College of civil and transportation engineering, Hohai University, Jiangsu 210098, China | ||