Geotechnical Evaluation of Loess Modifications as the Sustainable Compacted Soil Liner Material in Solid Waste Landfill

Zhang, Zhengrui; Matlan, Siti Jahara; Wang, Hao; Pishro, Ahad Amini; Zhang, Lili; Xian, Gao; Zhao, Ling; Liu, Xiaoyi; Zhao, Peigen

doi:10.3390/ma15144982

Cited by 11 publications

(6 citation statements)

References 21 publications

(24 reference statements)

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“…Attapulgite mainly improves the soil by filling the gaps between the soil particles and increasing the internal friction of the soil. Zhang et al [ 27 ] revealed that the mechanism of attapulgite-modified loess is that attapulgite fills the pores between loess particles and forms a sheet-like integral structure with loess, thus reducing the permeability coefficient. Furthermore, Chen et al [ 28 ] revealed that attapulgite has a special crystal structure and alternating properties, which provide it with excellent ion exchange and surface adsorption properties, which can effectively improve the physical properties of soil.…”

Section: Resultsmentioning

confidence: 99%

Using PVA and Attapulgite for the Stabilization of Clayey Soil

Mei

et al. 2022

Polymers

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Considering that, in the context of the ecological restoration of a large number of exposed rock slopes, it is difficult for existing artificial soil to meet the requirements of mechanical properties and ecological construction at the same time, this paper investigates the stabilization benefits of polyvinyl acetate and attapulgite-treated clayey soil through a series of laboratory experiments. To study the effectiveness of polyvinyl acetate (PVA) and attapulgite as soil stabilizer, a triaxial strength test, an evaporation test and a vegetation growth test were carried out on improved soil with different amounts of PVA content (0, 1%, 2%, 3%, and 4%) and attapulgite replacement (0, 2%, 4%, 6%, and 8%). The results show that the single and composite materials of polyvinyl acetate and attapulgite can increase the peak deviator stress of the sample. The addition of polyvinyl acetate can improve the soil strength by increasing the cohesion of the sample; the addition of attapulgite improves the soil strength mainly by increasing the internal friction angle of the sample. The strength of the composite is greatly improved by increasing the cohesion and internal friction angle of the sample at the same time. The effect of adding materials increased significantly with increasing curing age. Moreover, polyvinyl acetate and attapulgite improve the soil water retention of the soil by improving the water-holding capacity, so that the soil can still ensure the good growth of vegetation under long-term drought conditions. The scanning electron microscopy (SEM) images indicated that the PVA and attapulgite of soil affect the strength characteristics of soil specimens by the reaction of PVA and water, which changes the structure of the soil and, by the interweaving of attapulgite soil particles, acts as the skeleton of the aggregate. Overall, PVA and attapulgite can effectively increase clayey soil stability by improving the cohesive force and internal friction angle of clayey soil.

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Section: Resultsmentioning

confidence: 99%

Using PVA and Attapulgite for the Stabilization of Clayey Soil

Mei

et al. 2022

Polymers

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“…It has a certain bearing capacity in the dry state, but the cementation point between the particle skeleton will dissolve when it encounters water. Zhang Zhengrui et al [3][4] conducted a study on the seepage prevention of lime-modified loess on the embankment slope of deep collapsible loess. They found that lime piles and lime seepage prevention walls have good performance as transverse seepage prevention structures, and the performance of lime pile seepage prevention walls is better than that of lime compacted piles.…”

Section: Introductionmentioning

confidence: 99%

Study on anti-seepage mechanism of attapulgite-modified loess in Northwest China

Zhang,

Ahad

et al. 2024

IOP Conf. Ser.: Earth Environ. Sci.

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Loess is distributed widely in the arid areas in northwest China. Lanzhou city is located on the loess plateau, covered by a large area of deep collapsible Malan loess. Collapsible loess is a soft soil in engineering. It has a specific bearing capacity under dry conditions but will collapse after being immersed in water, which is unfavorable to engineering construction. This paper used the attapulgite abundant in the Zhangye City of Gansu Province as a modifier to improve the loess. The permeability test tested the permeability coefficient of the specimens under different dosages of attapulgite. The anti-permeability principle of attapulgite-modified loess was analyzed from the microscopic perspective by electron microscopy scanning (EMS) and nuclear magnetic resonance (NMR). The test results show that the permeability coefficient of attapulgite-modified loess decreases significantly compared with pure loess, but the permeability coefficient decreases gently when the content of attapulgite exceeds 10%. It was found that the anti-permeability mechanism of the modified loess was that the cohesive attapulgite particles filled the macropores of the loess particles, and the acicular attapulgite combined the loess particles to form a sheet structure, which reduced the porosity and permeability of the modified soil.

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“…However, the chemical compatibility of soil-bentonite cut-off walls with landfill leachate is poor, and its antifouling properties are easily affected by landfill leachate (most importantly, to increase the hydraulic conductivity of the cut-off walls) [6,[12][13][14][15][16][17]. Attapulgite is a clay mineral that is cheap and readily available [18,19], and it seems to be well suited for use in pollution containment barriers [20][21][22][23][24][25][26][27]; it is considered to be a viable alternative to bentonite in landfill cut-off walls [20,21,28]. Some research has experimentally confirmed the technical feasibility of using attapulgite as a landfill cut-off wall material [20,[29][30][31].…”

Section: Introductionmentioning

confidence: 99%

The Chemical Compatibility of Sand–Attapulgite Cut-Off Walls for Landfills

Zhang

RAO

Zhang

et al. 2023

Water

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Soil–bentonite cut-off walls have been widely used to control landfill pollution but they do not have good chemical compatibility with landfill leachate. Attapulgite can be substituted for bentonite in landfill cut-off walls. However, little is known about the chemical compatibility of attapulgite cut-off walls and leachate. This study experimentally investigated the chemical compatibility of attapulgite cut-off wall specimens with organic and inorganic contaminants and found that a sand–attapulgite cut-off wall has good chemical compatibility with organic contaminants. A CaCl2 solution was used to represent inorganic contaminants, and chemical oxygen demand (COD) was used as an indicator of organic content. The hydraulic conductivity of the cut-off wall initially decreased and then increased to become approximately constant as Ca2+ concentration increased. Changes in COD concentration were divided into a decreasing stage (0–10,000 mg/L) and a constant stage (10,000–40,000 mg/L). The increase or decrease in hydraulic conductivity was by no more than one order of magnitude. The increase in the hydraulic conductivity of the sand–attapulgite cut-off wall is explained in terms of bound water content and pore structure. An increase in Ca2+ concentration decreased the bound water content of the cut-off wall while the CaCl2 solution increased macropore and mesopore volume and decreased small pore volume in the sand–attapulgite cut-off wall. The purpose of this study was to elucidate the chemical compatibility of a sand–attapulgite cut-off wall with organic and inorganic contaminants and to increase the understanding of the interactions between the cut-off wall and the contaminants. The results of this research are informative for improving the application, design, and construction of sand–attapulgite cut-off walls.

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Geotechnical Evaluation of Loess Modifications as the Sustainable Compacted Soil Liner Material in Solid Waste Landfill

Cited by 11 publications

References 21 publications

Using PVA and Attapulgite for the Stabilization of Clayey Soil

Using PVA and Attapulgite for the Stabilization of Clayey Soil

Study on anti-seepage mechanism of attapulgite-modified loess in Northwest China

The Chemical Compatibility of Sand–Attapulgite Cut-Off Walls for Landfills

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