Effects of different mineral additives on pore structure and uniaxial compression creep characteristics of backfill

Abstract

Underground filling mining is crucial for resource recovery and surface protection. Long-term loading can cause creep deformation. This study added mineral additives during the preparation of the filling body and conducted uniaxial compression creep tests to reveal the creep deformation characteristics and microstructure evolution mechanism of the filling body during the loading process. The results indicate that, for the three mineral additives examined in this study within the tested dosage range (4 wt.%-8 wt.%), the 28-day UCS of the backfill increased relative to the control, accompanied by reduced creep deformation and creep rate. At the same stress level, the steady-state creep strain rate of the specimen with 8 wt.% sodium bentonite was reduced by approximately 65% compared to the control group, whereas the 4 wt.% dosage group showed only a 40% reduction. The modification effect of silica fume was relatively limited, and calcium bentonite was between the two. These three different mineral additives optimized the pore structure and improved the creep resistance through specific micro-mechanism pathways. The research results provide valuable insights into the long-term mechanical behavior of backfill body materials and offer a reference for the development of high-performance and sustainable underground backfill body systems.

Keywords

backfill mining / mineral additives / pore structure / green mining / creep characteristics

References

[1] Song Y, Yu C, Magazzino C, et al. . Transitioning the mining industry to a greener economy: An Asian perspective of mineral demand [J]. Resources Policy, 2025, 102: 105483

[2] He W, Liu L, Fang Z-y, et al. . Effect of long-term carbonation on strength and permeability of magnesia-coal based solid waste backfill materials [J]. Process Safety and Environmental Protection, 2025, 194: 892-903

[3] Gao Y-h, Liu L, Fang Z-y, et al. . Study on enhancing the performance of CO₂ sequestration materials from coal-based solid wastes via a two-stage carbonization mechanism [J]. Process Safety and Environmental Protection, 2026, 211: 108756

[4] He W, Liu L, Wei B-n, et al. . Study on mechanical properties and toughness characteristics of fiber reinforced storage backfill after carbonation curing [J]. Structures, 2025, 77: 108996

[5] Gao Y-h, Liu L, Fang Z-y, et al. . A backfill material without cementitious material: Carbonation curing magnesium slag based full solid waste backfill material [J]. Journal of Central South University, 2024, 31(5): 1507-1525

[6] Ru W-k, Li D-y, Han Z-y, et al. . Failure mechanism and damage constitutive model of cemented tailings backfill with different cement-tailings ratios under uniaxial compression [J]. Journal of Central South University, 2025, 32(8): 2979-2997

[7] Yu X, Yang K, He X, et al. . Research progress on multi-source coal-based solid waste (MCSW) resource utilization and backfill mining basic theory: A systematic literature review [J]. Process Safety and Environmental Protection, 2025, 195: 106670

[8] Koupouli N J F, Belem T, Rivard P, et al. . Direct shear tests on cemented paste backfill–rock wall and cemented paste backfill–backfill interfaces [J]. Journal of Rock Mechanics and Geotechnical Engineering, 2016, 8(4): 472-479

[9] Fall M, Nasir O. Mechanical behaviour of the interface between cemented tailings backfill and retaining structures under shear loads [J]. Geotechnical and Geological Engineering, 2010, 28(6): 779-790

[10] LAI Xing-ping, WU Long-quan, CAO Jian-tao, et al. Study on deformation response law of surrounding rock in solid backfill mining stope [J]. Advances in Civil Engineering, 2024: 8880234. DOI:https://doi.org/10.1155/2024/8880234.

[11] Hu S-c, Zhang C-x, Ru W-k, et al. . Creep properties and energy evolution characteristics of weakly cemented rock under step loading [J]. International Journal of Rock Mechanics and Mining Sciences, 2023, 170: 105428

[12] Fu J-x, Zhang B-y, Tan Y-y, et al. . Study on creep characteristics and damage evolution of surrounding rock and filling body (SR-FB) composite specimens [J]. Journal of Materials Research and Technology, 2023, 23: 5382-5399

[13] Zhu Q-w, Li T-c, Gao X, et al. . Deformation characteristics and failure evolution in deep high-stress roadways under creep action [J]. Engineering Failure Analysis, 2023, 154: 107689

[14] Liu W-b, Zhang S-guang. Creep constitutive model of rock based on strength time-dependent characteristics [J]. Engineering Fracture Mechanics, 2024, 298: 109914

[15] Niu L-l, Zhu W-c, Liu X-g, et al. . Shear creep deformation of rock fracture distrubed by dynamic loading [J]. International Journal of Rock Mechanics and Mining Sciences, 2024, 183: 105943

[16] Feng G-r, Ran H-y, Guo J, et al. . Experimental investigation on the deformation and strength properties of cemented gangue backfill column under long-term axial compression [J]. Structures, 2022, 43: 1558-1572

[17] Sun Q, Li B, Tian S, et al. . Creep properties of geopolymer cemented coal gangue-fly ash backfill under dynamic disturbance [J]. Construction and Building Materials, 2018, 191: 644-654

[18] Yu L-l, Xia J-w, Pu H, et al. . Creep characteristics and models of unconfined and BFRP-confined coal gangue concrete [J]. Journal of Building Engineering, 2025, 99: 111600

[19] Ma J-h, Wang Q, Jiao H-z, et al. . Solidification/stabilization and leaching behavior of heavy metals in low-binder cemented tailings backfill [J]. Case Studies in Construction Materials, 2024, 21: e03934

[20] Deng X-j, Jiao Y, Li S-c, et al. . Evaluation of the migration and environmental effects of metal elements within cementitious gangue-fly ash backfill in underground coal mines [J]. International Journal of Mining Science and Technology, 2024, 34(11): 1551-1562

[21] Nochaiya T, Jeenram T, Disuea P, et al. . Microstructure, compressive strength, and permeability of Portland-condensed silica fume cement [J]. Monatshefte für Chemie - Chemical Monthly, 2017, 148(7): 1363-1370

[22] Hu Y, Diao L, Lai Z-y, et al. . Effects of bentonite on pore structure and permeability of cement mortar [J]. Construction and Building Materials, 2019, 224: 276-283

[23] Guo P-z, Zhang J-m, Liu F, et al. . Experimental study on shear creep and long-term strength of clay-type muddy interlayer [J]. Applied Sciences, 2023, 13(22): 12151

[24] Yan Q, Qin S-f, Sang X-f, et al. . Research on creep characteristics of loading and unloading of hard Flint limestone [J]. Frontiers in Materials, 2023, 10: 1177733

[25] Wang J, Fu J-x, Song W-d, et al. . Mechanical properties, damage evolution, and constitutive model of rock-encased backfill under uniaxial compression [J]. Construction and Building Materials, 2021, 285: 122898

[26] Wang Y-r, Lu H-j, Wu J. Experimental investigation on strength and failure characteristics of cemented paste backfill-rock composite under uniaxial compression [J]. Construction and Building Materials, 2021, 304: 124629

[27] Fu J-x, Wang J, Song W-dong. Damage constitutive model and strength criterion of cemented paste backfill based on layered effect considerations [J]. Journal of Materials Research and Technology, 2020, 9(3): 6073-6084

[28] Chen M-x, Liu B, Li L-b, et al. . Rheological parameters, thixotropy and creep of 3D-printed calcium sulfoaluminate cement composites modified by bentonite [J]. Composites Part B: Engineering, 2020, 186: 107821

[29] Kaci A, Chaouche M, Andréani P A. Influence of bentonite clay on the rheological behaviour of fresh mortars [J]. Cement and Concrete Research, 2011, 41(4): 373-379

[30] Wang J-w, Zhu X-h, Wang J, et al. . Does the hydration process of supplementary cementitious materials affect the aging creep of blended cement paste [J]. Cement and Concrete Research, 2025, 191: 107826

[31] Wang J-w, Ding S, Du F-y, et al. . Interaction between calcium hydroxide and calcium-alumino-silicate-hydrate on micromechanical properties [J]. Construction and Building Materials, 2024, 449: 138321

[32] Chen G-f, Li S-j, Liu C, et al. . Rheological behavior and early-age hydration performance of blended cement pastes incorporating recycled brick powder and slag [J]. Construction and Building Materials, 2024, 436: 136925

[33] Richardson I G. Tobermorite/jennite- and tobermorite/calcium hydroxide-based models for the structure of C-S-H: Applicability to hardened pastes of tricalcium silicate, β-dicalcium silicate, Portland cement, and blends of Portland cement with blast-furnace slag, metakaolin, or silica fume [J]. Cement and Concrete Research, 2004, 34(9): 1733-1777

[34] Rodriguez E T, Richardson I G, Black L, et al. . Composition, silicate anion structure and morphology of calcium silicate hydrates (C-S-H) synthesised by silica-lime reaction and by controlled hydration of tricalcium silicate (C₃S) [J]. Advances in Applied Ceramics, 2015, 114(7): 362-371

[35] Wilson W, Sorelli L, Tagnit-Hamou A. Unveiling micro-chemo-mechanical properties of C–(A)–S–H and other phases in blended-cement pastes [J]. Cement and Concrete Research, 2018, 107: 317-336

[36] Zhang Y-r, Zhang X-s, Lu Z-c, et al. . New insight into the effects of silane-modified silica fume on the performance of cement pastes [J]. Cement and Concrete Research, 2025, 190: 107818

[37] Zhu X-h, Richardson I G. Morphology-structural change of C-A-S-H gel in blended cements [J]. Cement and Concrete Research, 2023, 168: 107156

[38] Cui Q, Maierdan Y, Chen B, et al. . Comparative research on the application of slag as an alternative to cement in binder-bentonite cutoff wall backfills [J]. Construction and Building Materials, 2022, 325: 126817

[39] He K, Deng Y-e, Cao Z-q, et al. . Engineering performance and microscale structure of activated high titanium slag-soil-cement-bentonite (HTS-SCB) slurry backfill [J]. Construction and Building Materials, 2023, 373: 130776

[40] Wang H-s, Chen D-f, Guo R-h, et al. . A preliminary study on the improvement of gangue/tailing cemented fill by bentonite: Flow properties, mechanical properties and permeability [J]. Materials, 2023, 16(20): 6802

[41] Calabria-Holley J, Papatzani S, Naden B, et al. . Tailored montmorillonite nanoparticles and their behaviour in the alkaline cement environment [J]. Applied Clay Science, 2017, 143: 67-75

[42] Khandelwal S, Rhee K Y. Evaluation of pozzolanic activity, heterogeneous nucleation, and microstructure of cement composites with modified bentonite clays [J]. Construction and Building Materials, 2022, 323: 126617

[43] Zheng W, Cui W, Miao R-cheng. Experimental study on influence of Na-bentonite on viscosity of cement-bentonite slurry [J]. Case Studies in Construction Materials, 2025, 22: e04306

[44] Gu X-y, Tan H-b, He X-y, et al. . Improvement in flexural strength of Portland cement by lamellar structured montmorillonite [J]. Construction and Building Materials, 2022, 329: 127208

[45] Yu P, Wang Z, Lai P-f, et al. . Evaluation of mechanic damping properties of montmorillonite/organo-modified montmorillonite-reinforced cement paste [J]. Construction and Building Materials, 2019, 203: 356-365

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