Engineering properties and microstructure of sodium polyacrylate-modified calcium bentonite

CHEN Hongxin; NIU Songying; FENG Shijin; XUE Qinpei; LI Zhengfei; SHI Fujiang

doi:10.11779/CJGE20240103

Volume 47 Issue 4

Turn off MathJax

Article Contents

Abstract

References

Supplements

Chinese Journal of Geotechnical Engineering > 2025 > 47(4): 860-868. > DOI: 10.11779/CJGE20240103

CHEN Hongxin, NIU Songying, FENG Shijin, XUE Qinpei, LI Zhengfei, SHI Fujiang. Engineering properties and microstructure of sodium polyacrylate-modified calcium bentonite[J]. Chinese Journal of Geotechnical Engineering, 2025, 47(4): 860-868. DOI: 10.11779/CJGE20240103

Citation:

PDF (7552 KB)

Engineering properties and microstructure of sodium polyacrylate-modified calcium bentonite

1.
Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China
2.
Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Shanghai 200092, China
3.
State Key Laboratory of Disaster Reduction in Civil Engineering, Shanghai 200092, China

More Information

Received Date: January 31, 2024
Available Online: June 18, 2024

Graphical Abstract

Abstract

Abstract

The abundant calcium-based bentonite (CaB) resources in China have gained attention as potential alternatives for preparing slurry when constructing cut-off walls. However, the limited swelling capacity and chemical compatibility of natural CaB pose critical challenges to enhancing its engineering properties. In this study, sodium polyacrylate (PAAS) is employed as a modifier to ameliorate CaB, and the optimal preparation conditions for sodium polyacrylate-modified calcium-based bentonite (PAAS―CaB) are determined through the processes of slaking, drying and grinding. The systematic tests on the engineering properties and microstructure of the modified bentonite were conducted. The results reveal that at a modifier content of 8%, the swelling index of PAAS―CaB reaches 34.0 mL/2g. The sodium polyacrylate modification significantly enhances the water absorption and swelling performance of CaB, along with improving its chemical compatibility, resulting in reduced permeability coefficient of the bentonite cake. With the increasing PAAS content, the Marsh viscosity of slurry increases, while the filtration loss and pH value decrease. The slurry density is primarily controlled by the bentonite content. Compared to the unmodified CaB, PAAS―CaB exhibits a superior overall lamellar structure at a microscopic scale, characterized by a smaller interlayer distance of montmorillonite crystalline layers. The sodium polyacrylate primarily modifies the calcium-based bentonite through bridging encapsulation and graft copolymerization. This study establishes a reliable foundation for optimizing the preparation process of PAAS―CaB and presents a feasible technical pathway for the engineering application of the calcium-based bentonite.
- cut-off wall,
- calcium-based bentonite,
- sodium polyacrylate,
- engineering property,
- microstructure

FullText(HTML)

References (21)

References

[1]	CHEN H X, XUE Q P, MA Z P, et al. Experimental study on barrier performance and durability under dry-wet cycles of fly ash based geopolymer cutoff wall backfill[J]. Construction and Building Materials, 2023, 368: 130415. doi: 10.1016/j.conbuildmat.2023.130415
[2]	NGUYEN T B, LEE C, LIM J, et al. Hydraulic characteristics of bentonite cake fabricated on cutoff walls[J]. Clays and Clay Minerals, 2012, 60(1): 40-51. doi: 10.1346/CCMN.2012.0600104
[3]	沈胜强, 杜延军, 魏明俐, 等. CaCl₂作用下PAC改良膨润土滤饼的渗透特性研究[J]. 岩石力学与工程学报, 2017, 36(11): 2810-2817. SHEN Shengqiang, DU Yanjun, WEI Mingli, et al. Hydraulic conductivity of filter cakes of polyanionic cellulose-amended bentonite slurries in calcium chloride solutions[J]. Chinese Journal of Rock Mechanics and Engineering, 2017, 36(11): 2810-2817. (in Chinese)
[4]	杨玉玲, 杜延军, 范日东, 等. 膨润土系隔离墙材料渗透特性研究综述[J]. 岩土工程学报, 2015, 37(增刊2): 210-216. YANG Yuling, DU Yanjun, FAN Ridong, et al. Advances in permeability for bentonite-based hydraulic containment barriers[J]. Chinese Journal of Geotechnical Engineering, 2015, 37(S2): 210-216. (in Chinese)
[5]	FU X L, ZHANG R, REDDY K R, et al. Membrane behavior and diffusion properties of sand/SHMP-amended bentonite vertical cutoff wall backfill exposed to lead contamination[J]. Engineering Geology, 2021, 284: 106037. doi: 10.1016/j.enggeo.2021.106037
[6]	查甫生, 杜延军, 刘松玉, 等. 自由膨胀比指标评价改良膨胀土的膨胀性[J]. 岩土工程学报, 2008, 30(10): 1502-1509. doi: 10.3321/j.issn:1000-4548.2008.10.014 ZHA Fusheng, DU Yanjun, LIU Songyu, et al. Evaluation of swelling capacity of stabilized expansive soils using free swell ratio method[J]. Chinese Journal of Geotechnical Engineering, 2008, 30(10): 1502-1509. (in Chinese) doi: 10.3321/j.issn:1000-4548.2008.10.014
[7]	YANG Y L, DU Y J, REDDY K R, et al. Phosphate-amended sand/Ca-bentonite mixtures as slurry trench wall backfills: assessment of workability, compressibility and hydraulic conductivity[J]. Applied Clay Science, 2017, 142: 120-127. doi: 10.1016/j.clay.2016.10.040
[8]	SHI F J, FENG S J, ZHENG Q T, et al. Effect of polyanionic cellulose modification on properties and microstructure of calcium bentonite[J]. Applied Clay Science, 2022, 228: 106633. doi: 10.1016/j.clay.2022.106633
[9]	BOHNHOFF G L, SHACKELFORD C D. Hydraulic conductivity of polymerized bentonite-amended backfills[J]. Journal of Geotechnical and Geoenvironmental Engineering, 2014, 140(3): 04013028. doi: 10.1061/(ASCE)GT.1943-5606.0001034
[10]	YANG Y L, REDDY K R, DU Y J, et al. Sodium hexametaphosphate (SHMP)-amended calcium bentonite for slurry trench cutoff walls: workability and microstructure characteristics[J]. Canadian Geotechnical Journal, 2018, 55(4): 528-537. doi: 10.1139/cgj-2017-0291
[11]	肖崇林, 范日东, 杨爱武. 苯酚溶液作用下CMC改性膨润土化学相容性试验研究[J]. 工程地质学报, 2021, 29(5): 1286-1294. XIAO Chonglin, FAN Ridong, YANG Aiwu. Experimental study on chemical compatibility of cmc treated bentonite subjected to phenol solutions[J]. Journal of Engineering Geology, 2021, 29(5): 1286-1294. (in Chinese)
[12]	CHUNG J, DANIEL D E. Modified fluid loss test as an improved measure of hydraulic conductivity for bentonite[J]. Geotechnical Testing Journal, 2008, 31(3): 243-251. doi: 10.1520/GTJ100005
[13]	DU Y J, SHEN S Q, TIAN K, et al. Effect of polymer amendment on hydraulic conductivity of bentonite in calcium chloride solutions[J]. Journal of Materials in Civil Engineering, 2021, 33(2): 04020452. doi: 10.1061/(ASCE)MT.1943-5533.0003518
[14]	SANTAMARINA J C, KLEIN K A, PALOMINO A, et al. Micro-scale aspects of chemical mechanical coupling: Interparticle forces and fabric[C]// Chemical Behaviour: Chemo-Mechanical Coupling from Nano-Structure to Engineering Applications, Rotterdam: Baclzema, 2002.
[15]	MORGAN A B, GILMAN J W. Characterization of polymer-layered silicate (clay) nanocomposites by transmission electron microscopy and X-ray diffraction: a comparative study[J]. Journal of Applied Polymer Science, 2003, 87(8): 1329-1338. doi: 10.1002/app.11884
[16]	THENG B K G. Clay-polymer interactions: summary and perspectives[J]. Clays and Clay Minerals, 1982, 30(1): 1-10.
[17]	张小红. 高吸水性树脂的结构设计与性能研究[D]. 西安: 西北工业大学, 2006. ZHANG Xiaohong. Study on Structure Design and Properties of Super Absorbent Resin[D]. Xi'an: Northwestern Polytechnical University, 2006. (in Chinese)
[18]	马靖, 陈永贵, 刘聪, 等. 化学作用下压实膨润土膨胀力相应机制研究进展[J]. 岩土工程学报, 2023, 41(10): 2042-2051. MA Jing, CHEN Yonggui, LIU Cong, et al. Research progress in mechanisms of swelling pressures of compacted bentonite under chemical conditions[J]. Chinese Journal of Geotechnical Engineering, 2023, 41(10): 2042-2051. (in Chinese)
[19]	YU Y, PENG R G, YANG C, et al. Eco-friendly and cost-effective superabsorbent sodium polyacrylate composites for environmental remediation[J]. Journal of Materials Science, 2015, 50(17): 5799-5808. doi: 10.1007/s10853-015-9127-5
[20]	常青. 絮凝学研究的新领域: 且有重金属捕集功能的高分子絮凝剂[J]. 环境科学学报, 2015, 35(1): 1-11. CHANG Qing. New research area of flocculation in water treatment-macromolecule flocculant with the function of trapping heavy metal[J]. Acta Scientiae Circumstantiae, 2015, 35(1): 1-11. (in Chinese)
[21]	ZENG J X, YE H Q, HUANG N D, et al. Selective separation of Hg(Ⅱ) and Cd(Ⅱ) from aqueous solutions by complexation–ultrafiltration process[J]. Chemosphere, 2009, 76(5): 706-710. doi: 10.1016/j.chemosphere.2009.05.019