Optimal selection of retarder for hemihydrate phosphogypsum-based filling cementitious materials: Balanced retardation and strength growth

Abstract

Hemihydrate phosphogypsum-based filling cementitious materials (HCM) have been widely applied in mine goaf treatment. However, the rapid setting of HCM slurry significantly limits its applicability. This study examined the impacts of citric acid (CA), sucrose (SU), and protein retarder (PR) on the setting time and strength of HCM through the determination of setting time and uniaxial compressive strength tests. The discussion addressed the factors influencing the retardation of three retarders. Hydration heat test, scanning electron microscope, mercury intrusion porosimetry and other test methods were used to analyze the retarding mechanism in alkaline environment from the perspectives of hydration and microstructure. The results indicated that the SU was the optimal choice for HCM, resulting in an extension of the final setting time by 5.45 h, and an increase in 3-day strength by 0.46 MPa with the addition of 0.05% SU. The increase in strength associated with the retarding effect was closely related to a greater enhancement in water reduction than the deterioration of retardation. The former indicated excess free water seeped out due to diminished adsorption force between particles, reducing the pores between hydration products. The latter occurred because the retarder modified the morphology of the hydration products to reduce the interlocking structures. These findings will ensure that HCM slurry is suitable for various application scenarios without compromising its strength and increasing costs.

Keywords

hemihydrate phosphogypsum / retarder / setting time / strength / microstructure

References

[1] Liu S-l, Wang Y-m, Wu A-xet al. . Performance evolution of alkali-activated phosphorus slag paste filling material: Effect of hemihydrate phosphogypsum content [J]. Process Safety and Environmental Protection. 2024, 187: 736-748.

[2] Wang Z-k, Wang Y-m, Dino G Aet al. . Degradation of hemihydrate phosphogypsum-based backfill in underground mining: Mechanical and microstructural insights on the effects of pH and temperature of mine water [J]. Process Safety and Environmental Protection. 2025, 193: 272-285.

[3] Qian W-m, Yang Y-y, Liu Z-wet al. . Enhanced absorption of SO₂ from phosphogypsum decomposition by phosphate slurry for phosphoric acid production [J]. Journal of Hazardous Materials. 2024, 465: 133431.

[4] Zhao Y-h, Zhou X-h, Zhou Q-set al. . Optimization design of anhydrous phosphogypsum-based backfill materials incorporating carbide slag and blast furnace slag by response surface method [J]. Minerals Engineering. 2024, 215108820.

[5] Ou L, Li R, Zhu H-zet al. . Upcycling waste phosphogypsum as an alternative filler for asphalt pavement [J]. Journal of Cleaner Production. 2023, 420138332.

[6] Dewindt M A, Weiksnar K D, Laux S Jet al. . A review of the suitability and performance of phosphogypsum as a material for road base and subbase construction [J]. Resources, Conservation and Recycling. 2025, 215108120.

[7] Costa R F, Firmano R F, Colzato Met al. . Sulfur speciation in a tropical soil amended with lime and phosphogypsum under long-term no-tillage system [J]. Geoderma. 2022, 406115461.

[8] Tsioka M, Voudrias E A. Comparison of alternative management methods for phosphogypsum waste using life cycle analysis [J]. Journal of Cleaner Production. 2020, 266121386.

[9] Zhang J-x, Cui K, Chang Jet al. . Phosphogypsum-based building materials: Resource utilization, development, and limitation [J]. Journal of Building Engineering. 2024, 91109734.

[10] Murali G, Azab M. Recent research in utilization of phosphogypsum as building materials: Review [J]. Journal of Materials Research and Technology. 2023, 25960-987.

[11] Rashad A M. Phosphogypsum as a construction material [J]. Journal of Cleaner Production. 2017, 166: 732-743.

[12] Akfas F, Elghali A, Aboulaich Aet al. . Exploring the potential reuse of phosphogypsum: A waste or a resource [J]. Science of the Total Environment. 2024, 908: 168196.

[13] Chen L, Luan X-y, Han Fet al. . Life cycle environmental and economic assessment of Phosphogypsum utilization in China [J]. Resources, Conservation and Recycling. 2025, 212107938.

[14] Gao S, Li W, Yuan K-ket al. . Properties and application of thixotropic cement paste backfill with molybdenum tailings [J]. Journal of Cleaner Production. 2023, 391136169.

[15] Lu W, Guo Z, Hu Het al. . Stability evaluation of mined-out area and Borehole Grouting Treatment-a case study in China [J]. Case Studies in Construction Materials. 2023, 19e02596.

[16] Su L-j, Wu S-y, Yu Fet al. . Utilizing municipal solid waste incineration fly ash for mine goaf filling: Preparation, optimization, and heavy metal leaching study [J]. Environmental Research. 2025, 266120594.

[17] Jiang G-z, Zhao L-l, Wu S-cet al. . Improvement in workability of new green hemihydrate phosphogypsum-based filling materials: Methods, mechanism and practice [J]. International Journal of Minerals, Metallurgy and Materials. 2025, 32(9): 2095-2108.

[18] Wang D-l, Zhang Q-l, Liu Bet al. . Enhanced immobilization of fluoride in phosphogypsum-based cement-free paste backfill modified by polyaluminum chloride and its mechanism [J]. Construction and Building Materials. 2025, 458: 139622.

[19] Zhao Y-h, Zhou X-h, Zhou Q-set al. . Solid waste binder cemented dihydrate phosphogypsum aggregate to prepare backfill material [J]. Minerals Engineering. 2025, 226109249.

[20] Liu Y-k, Wang Y-m, Chen Q-S. Using cemented paste backfill to tackle the phosphogypsum stockpile in China: A down-to-earth technology with new vitalities in pollutant retention and CO₂ abatement [J]. International Journal of Minerals, Metallurgy and Materials. 2024, 3171480-1499.

[21] Alainachi I, Fall M. Chemically induced changes in the geotechnical response of cementing paste backfill in shaking table test [J]. Journal of Rock Mechanics and Geotechnical Engineering. 2021, 133513-528.

[22] Zhou S-t, Li X-b, Zhou Y-net al. . Effect of phosphorus on the properties of phosphogypsum-based cemented backfill [J]. Journal of Hazardous Materials. 2020, 399: 122993.

[23] Jiang G-z, Wu A-x, Wang Y-met al. . The rheological behavior of paste prepared from hemihydrate phosphogypsum and tailing [J]. Construction and Building Materials. 2019, 229116870.

[24] Jiang G-z, Zhao L-l, Wu S-cet al. . A systematic review of cemented paste backfill technology for cleaner and efficient utilization of phosphogypsum in China [J]. Minerals Engineering. 2025, 231109468.

[25] Chen Q-s, Gao L-z, Wu A-xet al. . Alkaline-washed phosphogypsum-based cemented paste backfill prepared using steel slag and blast furnace slag: Mechanical properties, fluoride immobilization, and hydration mechanism [J]. Case Studies in Construction Materials. 2024, 21e04028.

[26] Wang D-l, Na Q, Liu Y-ket al. . Hydration process and fluoride solidification mechanism of multisource solid waste-based phosphogypsum cemented paste backfill under CaO modification [J]. Cement and Concrete Composites. 2024, 154105804.

[27] Zhao Y-h, Zhu H-y, Zhou X-het al. . Adding silica fume and calcium carbide residue to enhance the performance of β -hemihydrate phosphogypsum for backfill mining [J]. Construction and Building Materials. 2025, 467140420.

[28] Wang J-d, Jiang G-z, Wu A-xet al. . Rheological behavior of a novel quick-setting binder under resting and mixing and its relations to hydration and microstructure [J]. Construction and Building Materials. 2022, 357129313.

[29] Ding X-l, Huang W, Li Yet al. . Study on retarding feature and retardation mechanism of various retarding materials on gypsum as a construction material: A review [J]. Journal of Building Engineering. 2023, 72106569.

[30] Zhang Y-y, Yang J-s, Cao X-Y. Effects of several retarders on setting time and strength of building gypsum [J]. Construction and Building Materials. 2020, 240117927.

[31] Tang X, Yang Y, Hu X-Z. Retarder design for long open-hole well cementing through the interfacial adsorption [J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2023, 677132278.

[32] Saeed M K, Rahman M K, Alfawzan Met al. . Evaluation of date kernel powder (DKP) for potential use as setting and hydration retarder in concrete [J]. Journal of Building Engineering. 2022, 57104855.

[33] Ataie F F, Juenger M C G, Taylor-Lange S Cet al. . Comparison of the retarding mechanisms of zinc oxide and sucrose on cement hydration and interactions with supplementary cementitious materials [J]. Cement and Concrete Research. 2015, 72128-136.

[34] Zhang L-h, Chen P-y, Xu Y-cet al. . Upcycling waste flavedo into a bio-admixture of set retarder and compressive strength enhancer for cement-based materials [J]. Journal of Cleaner Production. 2022, 332: 130060.

[35] Nedunuri A S S S, Muhammad S. Development and field validation of pumpable alkali-activated ground granulated blast furnace slag binder-based concrete using sodium gluconate as a retarder [J]. Journal of Building Engineering. 2024, 98111295.

[36] Ahmad S, Lawan A, Al-Osta M. Effect of sugar dosage on setting time, microstructure and strength of Type I and Type V Portland cements [J]. Case Studies in Construction Materials. 2020, 13e00364.

[37] Ahmadi Moghadam H, Mirzaei A. Comparing the effects of a retarder and accelerator on properties of gypsum building plaster [J]. Journal of Building Engineering. 2020, 28101075.

[38] Zou D-h, Zhang Z-j, Wang D-M. Influence of citric acid and sodium gluconate on hydration of calcium sulfoaluminate cement at various temperatures [J]. Construction and Building Materials. 2020, 263120247.

[39] Ding X-l, Li Y, Huang Wet al. . Green and effective route to convert chromium-free leather waste into protein retarding material for building gypsum [J]. Construction and Building Materials. 2024, 411134662.

[40] Bruere G M. Set-retarding effects of sugars in Portland cement pastes [J]. Nature. 1966, 212(5061): 502-503.

[41] Bishop M, Barron A R. Cement hydration inhibition with sucrose, tartaric acid, and lignosulfonate: analytical and spectroscopic study [J]. Industrial & Engineering Chemistry Research. 2006, 45217042-7049.

[42] Jiang G-z, Wu A-x, Wang Y-met al. . Low cost and high efficiency utilization of hemihydrate phosphogypsum: Used as binder to prepare filling material [J]. Construction and Building Materials. 2018, 167: 263-270.

[43] Jiang G-z, Zhao L-l, Li Het al. . Immobilization of phosphorus and fluorine from whole phosphogypsum-based cemented backfill material with self-cementing properties [J]. Construction and Building Materials. 2024, 438: 137072.

[44] Magallanes-Rivera R X, Escalante-García J I, Gorokhovsky A. Hydration reactions and microstructural characteristics of hemihydrate with citric and malic acid [J]. Construction and Building Materials. 2009, 23(3): 1298-1305.

[45] Ai C-m, Yu A-j, Liu Cet al. . Analysis of physical characteristics and mechanism of retarder to stratified cemented backfill [J]. Scientific Reports. 2024, 14: 13711.

[46] Saedi A, Jamshidi-Zanjani A, Darban A K. A review of additives used in the cemented paste tailings: Environmental aspects and application [J]. Journal of Environmental Management. 2021, 289112501.

[47] Singh M. Effect of phosphatic and fluoride impurities of phosphogypsum on the properties of selenite plaster [J]. Cement and Concrete Research. 2003, 3391363-1369.

[48] Du Q, Wang R-y, Deng Z-yet al. . Structural characterization and calcium absorption-promoting effect of sucrose-calcium chelate in Caco-2 monolayer cells and mice [J]. Journal of Food Science. 2024, 8931773-1790.

[49] Li J-b, Lu S-y, Wu S-qet al. . The breakdown of protein hydrogen bonding networks facilitates biotransformation of protein wastewaters during anaerobic digestion methanogenesis: Focus on protein structure and conformation [J]. Environmental Research. 2022, 208: 112735.

[50] Jiang G-z, Wu A-x, Wang Y-met al. . Determination of utilization strategies for hemihydrate phosphogypsum in cemented paste backfill: Used as cementitious material or aggregate [J]. Journal of Environmental Management. 2022, 308114687.

[51] Hu Y-y, Zhou C-y, Zeng X-qet al. . Phosphate type dependent phosphorylation on the interfacial and emulsion stabilizing behaviors of goose liver protein: Perspective of protein charging [J]. Colloids and Surfaces B: Biointerfaces. 2024, 238113872.

[52] Wang Z-r, Jiang H-q, Fu Yet al. . Calcined alunite-modified alkali-sulphate-activated slag as a novel binder for high-performance cemented paste backfill [J]. Journal of Building Engineering. 2024, 91109687.

[53] Huang Y-y, Xu C, Li H-xet al. . Utilization of the black tea powder as multifunctional admixture for the hemihydrate gypsum [J]. Journal of Cleaner Production. 2019, 210231-237.

[54] Singh N B, Middendorf B. Calcium sulphate hemihydrate hydration leading to gypsum crystallization [J]. Progress in Crystal Growth and Characterization of Materials. 2007, 53(1): 57-77.

[55] Chen X-m, Wang Q-y, Wu Q-het al. . Hydration reaction and microstructural characteristics of hemihydrate phosphogypsum with variable pH [J]. Construction and Building Materials. 2022, 316: 125891.

[56] Jin Z-h, Wang L-y, Su Yet al. . Effect of different retarders on setting time and mechanical properties of hemihydrate phosphogypsum-calcium sulfoaluminate cement composite binder [J]. Construction and Building Materials. 2024, 411134339.

[57] He G-p, Kong D-y, Chen X-get al. . Preparation of C-S-H gels by mechanochemistry and its influences on properties of super-retarded cement-based materials with sucrose [J]. Cement and Concrete Composites. 2024, 153105734.

[58] Liao G-s, Mei J-p, Xie J-cet al. . Effect of modified amino acids on hydration behavior of β -hemihydrate phosphogypsum [J]. Developments in the Built Environment. 2024, 19100491.

[59] Niu F-j, Wang Y-r, Wang Z-yet al. . Experimental study of polyurethane-cement composite reinforcing talik beneath subgrade in permafrost regions: Exothermic characteristics, durability and micro-mechanism [J]. Journal of Materials Research and Technology. 2025, 34110-124.

[60] LI Xian-bo, DU Wei-fan. Rapid synthesis of α -hemihydrate phosphogypsum in MgCl₂ solution by microwave heating [J]. Langmuir, 2024: acs. langmuir. 4c01955. DOI: https://doi.org/10.1021/acs.langmuir.4c01955.

[61] Ding X-l, Li Y, Chen Jet al. . Sustainable utilization of finished leather wastes: A novel collagen hydrolysate-based gypsum additive with high-retarding performance [J]. Process Safety and Environmental Protection. 2023, 172: 451-461.

[62] Zhang C, Wang J, Song W-det al. . Pore structure, mechanical behavior and damage evolution of cemented paste backfill [J]. Journal of Materials Research and Technology. 2022, 17: 2864-2874.

[63] O’Farrell M, Wild S, Sabir B B. Pore size distribution and compressive strength of waste clay brick mortar [J]. Cement and Concrete Composites. 2001, 23(1): 81-91.

[64] Liu S-l, Wang Y-m, Wu A-xet al. . Early mechanical strength, hydration mechanism and leaching behavior of alkali-activated slag/fly ash paste filling materials [J]. Journal of Building Engineering. 2024, 84: 108481.

[65] Sant G, Bentz D, Weiss J. Capillary porosity depercolation in cement-based materials: Measurement techniques and factors which influence their interpretation [J]. Cement and Concrete Research. 2011, 418854-864.

[66] Zhao L-y, Wang C-w, Na Set al. . A study of blast furnace slag on the mechanical properties improvement and microstructure of hemihydrate phosphogypsum pretreated by calcium hydroxide [J]. Case Studies in Construction Materials. 2025, 22e04121.

[67] Akfas F, Elghali A, Toubri Yet al. . Environmental assessment of phosphogypsum: A comprehensive geochemical modeling and leaching behavior study [J]. Journal of Environmental Management. 2024, 359120929.

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