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Hou, et al.

facilitated the formation and homogeneous pumpability and homogeneity. Moreover, curing tests
distribution of hydration products, thereby enhancing revealed that improved particle packing at higher i
k
overall strength performance. These findings suggest values enhanced compressive strength across all
that a moderate increase in fine particle content can curing ages, attributable to more uniform distribution
effectively improve the mechanical properties of the of hydration products and denser microstructure
slurry, fulfilling both early-age and long-term strength formation.
requirements for engineering applications. In summary, the results underscore the importance
Furthermore, future research should emphasize of jointly optimizing mass concentration and particle
the recycling of industrial wastes, such as coal sludge gradation to achieve superior slurry performance.
and fly ash as sustainable alternatives to diminishing By tailoring these parameters, it is possible to
natural ore resources. This strategy not only aligns ensure excellent workability, mechanical strength,
with the overarching objective of utilizing waste and long-term stability, thereby highlighting the
materials for mine filling applications but also practical potential of coal gangue-fly ash slurries
addresses the growing need for eco-friendly and in backfilling and related engineering applications.
cost-effective solutions in the mining industry. In These findings not only provide technical guidance
particular, the incorporation of mechanical activation for slurry design but also demonstrate a feasible
and leaching technologies may significantly enhance
the performance of such mixtures by improving pathway for the resourceful reuse of coal gangue
mechanical strength and reducing the release of and fly ash, supporting sustainable solid waste
hazardous substances. 35,36 These advancements could management and environmentally friendly mine
further expand the practical relevance of coal gangue- backfilling practices.
fly ash systems and open promising directions for
future investigation. Acknowledgments

4. Conclusion None.

The present study systematically investigates the Funding
mineral composition, rheological behavior, and
stability of coal gangue-fly ash mixed slurries, with This research was funded by the Guizhou Provincial
particular attention to the effects of mass concentration Energy Bureau Science and Technology Project (Project
and particle size distribution. Rheological tests name: Technical Research and Development of Coal
demonstrate that the slurry exhibits Bingham fluid Gangue Underground Backfill Mining Technology and
characteristics across all tested concentrations, with Its Pilot Application by Guizhou Zhaping Coal Industry
both yield stress and viscosity increasing with higher Co., Ltd; Grant number: 2023–68).
mass concentration. An optimal concentration of
72% was identified, at which the slurry achieved a Conflict of interest
favorable balance between flowability and resistance
to segregation. This concentration effectively The authors declare no competing interests.
minimized particle settling and stratification while
maintaining adequate pumpability for engineering Author contributions
applications. In addition to mass concentration,
particle size distribution significantly influenced Conceptualization: Jianjun Hou, Linqiang Mao
both the rheological and mechanical properties of Formal analysis: Zhigang Li, Zhiling Ren
the slurry. As the grading index (i ) increased from Methodology: Jian Wang, Yang Yang, Zhongquan Liu
k
0.88 to 0.92, the slurry’s flow diameter and slump Writing – original draft: Jianjun Hou, Zhigang Li
decreased, indicating reduced flowability due to Writing – review & editing: Linqiang Mao, Zhiling Ren
higher fine particle content and increased internal
resistance. However, a grading index of i = 0.91 Availability of data
k
yielded the most favorable overall performance, with
a high slump (57.2 cm), low water separation (3.2%), Data are available from the corresponding author upon
and minimal segregation (17.3%), ensuring optimal reasonable request.

Volume 22 Issue 5 (2025) 190 doi: 10.36922/AJWEP025200154