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<p>Improving the roof-contacted filling rate (RCFR) is considered a critical technology for guaranteeing the safety of filling stope in mines. In this research, the approach of incorporating a plastic expansive agent (PEA) into the filling slurry to achieve volume expansion was employed. The study investigated the effects of slurry mass concentration, cementitious powder (CP) dosage, and PEA dosage on the uniaxial compressive strength (UCS) and volume change rate (VCR) of cemented tailings backfill (CTB). In addition, the analysis of the stress–strain and damage characteristics of CTB was explored. The microstructure was detected using X-ray diffraction (XRD), thermogravimetry–differential scanning calorimetry (TG-DSC), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) tests. The field industrial test was conducted to validate the roof-contacted filling effect of PEA on CTB. The experimental results revealed that the impact of various factors on the UCS of CTB followed the sequence of CP dosage, slurry mass concentration, and PEA dosage. In contrast, the VCR of CTB was most significantly influenced by PEA dosage, followed by slurry mass concentration and CP dosage. Furthermore, an inverse relationship was observed between PEA dosage and UCS, whereas a direct relationship existed between PEA dosage and VCR. CTB samples without the addition of PEA predominantly exhibited shrinkage characteristics at all curing ages. A critical threshold of PEA dosage was identified at 0.024%, causing CTB with the addition of PEA to undergo a transformation from shrinkage to expansion characteristics. The microscopic analysis indicated that the PEA enhanced the pore structure without altering the types of hydration products. The field-measured outcomes closely corresponded with the experimental results, fulfilling the criteria for filling strength and roof-contacted filling. This study will provide theoretical guidance and engineering suggestions for the application of roof-contacted filling in mines.</p>

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Study on Mechanical Strength, Volume Stability, and Hydration Mechanism of Cemented Tailings Backfill with Plastic Expansive Agent

  • 期刊论文

  • 发表日期：

    2025年2月25日

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  • Minzhe Zhang,
  • Yiming Wang,
  • Aixiang Wu,
  • Zhuen Ruan,
  • Zhikai Wang,
  • Shulong Liu

摘要

Improving the roof-contacted filling rate (RCFR) is considered a critical technology for guaranteeing the safety of filling stope in mines. In this research, the approach of incorporating a plastic expansive agent (PEA) into the filling slurry to achieve volume expansion was employed. The study investigated the effects of slurry mass concentration, cementitious powder (CP) dosage, and PEA dosage on the uniaxial compressive strength (UCS) and volume change rate (VCR) of cemented tailings backfill (CTB). In addition, the analysis of the stress–strain and damage characteristics of CTB was explored. The microstructure was detected using X-ray diffraction (XRD), thermogravimetry–differential scanning calorimetry (TG-DSC), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) tests. The field industrial test was conducted to validate the roof-contacted filling effect of PEA on CTB. The experimental results revealed that the impact of various factors on the UCS of CTB followed the sequence of CP dosage, slurry mass concentration, and PEA dosage. In contrast, the VCR of CTB was most significantly influenced by PEA dosage, followed by slurry mass concentration and CP dosage. Furthermore, an inverse relationship was observed between PEA dosage and UCS, whereas a direct relationship existed between PEA dosage and VCR. CTB samples without the addition of PEA predominantly exhibited shrinkage characteristics at all curing ages. A critical threshold of PEA dosage was identified at 0.024%, causing CTB with the addition of PEA to undergo a transformation from shrinkage to expansion characteristics. The microscopic analysis indicated that the PEA enhanced the pore structure without altering the types of hydration products. The field-measured outcomes closely corresponded with the experimental results, fulfilling the criteria for filling strength and roof-contacted filling. This study will provide theoretical guidance and engineering suggestions for the application of roof-contacted filling in mines.