Permeability, Pore, and Structural Parameters of Undisturbed Silty Clay Presented in Landfill Leachate

Lu, Haijun; Wang, Chaofeng; Li, Dinggang; Li, Jixiang; Wan, Yong

doi:10.1007/s11270-020-04568-0

Cited by 4 publications

(3 citation statements)

References 25 publications

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“…During 0~100 h, the permeability coefficient of the sample was in a stage of rapid increase; at 100~250 h, the permeability coefficient was slowly decreasing; after 250 h, the permeability coefficient was basically stable, and the permeability coefficient of MS1~MS9 test was 0.39~5.75 × 10 −7 cm/s. At the initial stage of permeability, some of the pores in the sample were not filled with water and were in an unsaturated state, which led to the larger seepage velocity of water under the action of capillary force, and thus the increase in the permeability coefficient [23,24]. With the extension of the permeation time, the sample reached the saturation state, and the unreacted calcium-containing solid waste fully contacted with water to form a gelled geopolymer under the action of hydration reaction, thus reducing the porosity and permeability coefficient of the sample.…”

Section: Hydraulic Conductivity Coefficientmentioning

confidence: 99%

Mechanical Characteristics and Micro-Mechanism of Modified Dredged Sludge Based on Calcium-Containing Solid Waste Used as Landfill Cover Materials

Shang

2022

Processes

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In order to prepare a new type of landfill covering material for closure, we used industrial calcium-containing waste (construction rubbish, slag, desulfurized gypsum and fly ash) to modify the dredged urban sludge. Shrink, unconfined compression, shear and infiltration tests were performed to obtain the volume shrinkage, compressive strength, shear strength and permeability coefficient of the modified sludge, as well as the permeability coefficient under the action of wet and dry cycles. Comprehensive characterization of the modified sludge using X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy with energy dispersive spectroscopy detection methods, resulted in the hydration products, molecular groups and microstructure characteristics of the modified sludge and revealed the modification mechanism of calcium-containing waste to sludge. After natural curing for 28 d, the volume shrinkage rate of the modified sludge sample was 2.6~8.3%, the unconfined compressive strength was 7.9~14.5 MPa, the cohesion force c was 179~329 kPa, and the internal friction angle φ was 42.59~53.60°. After six wet and dry cycles, there were no cracks in the modified sludge; the permeability coefficient of the modified sludge reached stability at 0.84–11.1 × 10−7 cm/s; and the permeability coefficient of MS7 sample was less than 1 × 10−7 cm/s, which met the engineering anti-seepage requirements of the landfill closure cover. The industrial calcium-containing waste by alkali formed C–S–H and C–A–S–H gelled geopolymer, which filled the gaps between soil particles to form a strong soil cement skeleton. Therefore, the mix ratio of sludge:construction waste:slag:fly ash:desulfurized gypsum was 50:22:15:8:5. Calcium-containing solid waste modified sludge can be used as a cover material for landfill closure.

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Section: Hydraulic Conductivity Coefficientmentioning

confidence: 99%

Mechanical Characteristics and Micro-Mechanism of Modified Dredged Sludge Based on Calcium-Containing Solid Waste Used as Landfill Cover Materials

Shang

2022

Processes

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“…Therefore, the application of a layer with very low permeability is necessary to reduce the infiltration of contaminated water into the soil while simultaneously eliminating pollutants. Several studies have shown that the Ks in low permeability soil samples change with infiltration of the water that contains chemical or biological agents (Francisca & Glatstein, 2010;Lu et al, 2020;Montoro & Francisca, 2010).…”

Section: Introductionmentioning

confidence: 99%

Examining long-term variability in saturated hydraulic conductivity of sandy soils and its influencing factors

Ashouri,

Pittari,

Moon

et al. 2023

Preprint

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Saturated hydraulic conductivity (Ks) is a crucial parameter that influences water flow in saturated soils, with applications in various fields such as surface water runoff, soil erosion, drainage, and solute transport. However, accurate estimation of Ks is challenging due to temporal and spatial uncertainties. This study addresses the knowledge gap regarding the long-term behaviour of Ks in sandy soils with less than 10% fine particles. The research investigates the changes in Ks over a long period of constant head tests and examines the factors influencing its variation. Two sandy samples were tested using a hydraulic conductivity cell, and the hydraulic head and discharge were recorded for over 50 days. The results show a general decline in Ks throughout the test, except for brief periods of increase. Furthermore, the relationship between flow rate and hydraulic head gradient does not follow the expected linear correlation from Darcy’s law, highlighting the complex nature of sandy soil hydraulic conductivity. The investigation of soil properties in three different sections of the samples before and after the tests revealed a decrease in the percentage of fine particles and a shift in specific gravity from the bottom to the top of the sample, suggesting particle migration along the flow direction. Factors such as clogging by fine particles and pore pressure variation contribute to the changes in Ks. The implications of this study have far-reaching effects on various geotechnical engineering applications. These include groundwater remediation, geotechnical stability analysis, and drainage system design.

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“…Permeability and water transmission through the soil are among the most notable design parameters for land lls (Chai and Prongmanee, 2020;Lu et al, 2020). The soil permeability is dependent on several factors including uid viscosity, pore size and distribution, gradation curve, void ratio, and saturation level.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Evaluation of Thermal Stabilization of Marl Soils Considering Permeability Variations

Amiri

Dehghani

Papi

2022

Preprint

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Heat alters the engineering behavior of soils. Marl soils are highly-erodible sedimentary deposits composed of clay minerals and calcium carbonate. Clay minerals and calcium carbonate in marl soils considerably influence the engineering behavior of such soils. Soils can be exposed to heat for a variety of reasons leading to changes in the physical, mechanical, and microstructural properties, in particular the engineering properties of marl soils. In the design of geo-environmental projects, the results of soil mechanics, especially the permeability coefficient, directly influence the design outcomes. Accordingly, this study aimed at evaluating the effect of heat treatment on the engineering behavior and permeability coefficient of marl soils from a microstructural perspective. To this end, the marl soil was heated to 25–900°C for 2 h. The changes in the engineering properties of marl soils at different temperatures were studied by macrostructural (gradation, Atterberg limits, loss-on-drying, Unconfined Compressive Strength (UCS) and permeability) and microstructural (XRD and SEM) investigations. The results were suggestive of the considerable effect of heat treatment on the engineering behavior of marl soils, as the compressive strength of marl soils increased by 100 folds, and the permeability coefficient reduced by about 6 times at 700°C.

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Permeability, Pore, and Structural Parameters of Undisturbed Silty Clay Presented in Landfill Leachate

Cited by 4 publications

References 25 publications

Mechanical Characteristics and Micro-Mechanism of Modified Dredged Sludge Based on Calcium-Containing Solid Waste Used as Landfill Cover Materials

Mechanical Characteristics and Micro-Mechanism of Modified Dredged Sludge Based on Calcium-Containing Solid Waste Used as Landfill Cover Materials

Examining long-term variability in saturated hydraulic conductivity of sandy soils and its influencing factors

Microstructural Evaluation of Thermal Stabilization of Marl Soils Considering Permeability Variations

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