Geomechanics and Engineering

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Effects of chloride ion transport characteristics and water pressure on mechanical properties of cemented coal gangue-fly ash backfill

  • Dawei Yin (State Key Laboratory of Mine Disaster Prevention and Control, Shandong University of Science and Technology) ;
  • Zhibin Lu (State Key Laboratory of Mine Disaster Prevention and Control, Shandong University of Science and Technology) ;
  • Zongxu Li (State Key Laboratory of Mine Disaster Prevention and Control, Shandong University of Science and Technology) ;
  • Chun Wang (Henan Polytechnic University) ;
  • Xuelong Li (State Key Laboratory of Mine Disaster Prevention and Control, Shandong University of Science and Technology) ;
  • Hao Hu (State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines, Anhui University of Science and Technology)
  • Received : 2024.03.28
  • Accepted : 2024.07.04
  • Published : 2024.07.25
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Abstract

In paste backfill mining, cemented coal gangue-fly ash backfill (CGFB) can effectively utilize coal-based solid waste, such as gangue, to control surface subsidence. However, given the pressurized water accumulation environment in goafs, CGFB is subject to coupling effects from water pressure and chloride ions. Therefore, studying the influence of pressurized water on the chlorine salt erosion of CGFB to ensure green mining safety is important. In this study, CGFB samples were soaked in a chloride salt solution at different pressures (0, 0.5, 1.5, and 3.0 MPa) to investigate the chloride ion transport characteristics, hydration products, micromorphology, pore characteristics, and mechanical properties of CGFB. Water pressure was found to promote chloride ion transfer to the CGFB interior and the material hydration reaction; enhance the internal CGFB pore structure, penetration depth, and chloride ion content; and fill the pores between the material to reduce its porosity. Furthermore, the CGFB peak uniaxial compression strain gradually decreased with increasing soaking pressure, whereas the uniaxial compressive strength first increased and then decreased. The resulting effects on the stability of the CGFB solid-phase hydration products can change the overall CGFB mechanical properties. These findings are significant for further improving the adaptability of CGFB for coal mine engineering.

Keywords

Acknowledgement

The research described in this paper was financially supported by the National Natural Science Foundation of China [Grant Nos. 52274128 and 52174159], the Taishan Scholars Project Special Fund, the Open Fund for the Henan Key Laboratory for Green and Efficient Mining & Comprehensive Utilization of Mineral Resources (KCF2204), and the Open Fund for the State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines [Grant No. SKLMRDPC22KF01]. We would like to thank Editage (www.editage.cn) for English language editing.

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