Effect of Sand Particle Size on Hydraulic-Mechanical Behavior of Bentonite-Sand Mixtures

Lu, Tian-Hao; Sun, Wenjing; Liu, Ke; Tan, Yunzhi

doi:10.1007/s12205-022-1271-2

Cited by 9 publications

(5 citation statements)

References 37 publications

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“…Gupt et al(2021) found that no matter the compacted state and the amount of fly ash, the UCS of fly-bentonite mixed soil increased compared with pure bentonite. Lu et al (2022) studied the effect of sand particle content and particle size on the permeability of bentonite-sand mixed soil, and the results showed that under the condition of the same sand particle content, the particle size of sand had no significant influence on the permeability area and permeability path length of the mixed soil. With the in-depth study of soil-bentonite mixed soils, many scholars have established a prediction model for the permeability coefficient of mixed soils from the aspects of specific surface area, pore ratio, basic physical properties and compressibility (Chapuis RP 1990, Sällfors and Öberg-Högsta 2002, Chapuis RP 2004, Hansen 2004, Yeo et al2005, Fan et al2014, and Khalid et al2023.…”

Section: Introductionmentioning

confidence: 99%

Effects of Freeze–Thaw Cycle on Permeability and Compression Properties of Aeolian Soil–Bentonite Mixture

Chen,

Peng,

et al. 2024

Iran J Sci Technol Trans Civ Eng

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： Since all the soil materials within 200 kilometers of the proposed dam site are aeolian sedimentary soil, the permeability is not in line with the engineering performance of the core dam materials. Moreover, in the construction of a large core dam in a high altitude area, the core wall dam materials will be subjected to repeated freeze-thaw action during the winter construction of the dam, resulting in changes in the particle distribution and particle connection inside the filled dam materials. Thus, the engineering properties and filling quality of dam materials are changed. Therefore, in this paper, two types of bentonite were used to improve the existing aeolian soil material, and the aeolian soil-Na/Ca-bentonite mixture (ANB/ACB) with different bentonite content (0%, 2%, 4%, 8%, 16%, 32%) was subjected to different freezing through particle separation test, variable head permeability test and consolidation compression test. The influence of the number of thawing cycles (0, 1, 5, 10) on the permeability and compression properties was studied. The test results show that: (1) the increase of bentonite content, the inhomogeneity coefficient, curvature coefficient and clay content of ANB/ACB increase gradually, and the inhomogeneity coefficient, curvature coefficient and clay content of ACB are greater than those of ANB under the same bentonite content,(2)the continuous incorporation of Na/Ca-bentonite, the permeability coefficient of ANB/ACB decreases, and the decreasing trend is gradually becoming slight; the permeability coefficient of ANB increases gradually after the freeze-thaw cycle, while the permeability coefficient of ACB decreases with the increase of freeze-thaw times when the bentonite content is high;(3) the increase of consolidation normal stress, the 2 compression coefficients of ANB and ACB decrease rapidly, and their decreasing rates also decrease gradually.Meanwhile, under the same normal stress condition, the compression coefficient (a v ) of ANB/ACB decreases gradually with the increase of bentonite content, and increases gradually with the increase of freeze-thaw cycles; and (4) the compression index of ANB/ACB gradually increases with the continuous incorporation of bentonite content, and with the increase of bentonite content, the compression index of ACB develops from roughly equal to that of ANB to that of ACB greater than that of ANB. At the same time, the effect of the freeze-thaw cycle on the compression index of ACB/ANB is deteriorating, and the first freeze-thaw cycle has the greatest effect on the compression index of both ACB and ANB. In addition, the effects of bentonite content and freeze-thaw effect on the mixed soil samples are analyzed from the microscopic scale through electron microscope scanning. It is found that the addition of bentonite increases the proportion of fine particles in the mixed soil samples, while the freezethaw cycle effect changes the pore structure and particle size of the soil samples. This study provides scientific support for dam construction...

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Section: Introductionmentioning

confidence: 99%

Effects of Freeze–Thaw Cycle on Permeability and Compression Properties of Aeolian Soil–Bentonite Mixture

Chen,

Peng,

et al. 2024

Iran J Sci Technol Trans Civ Eng

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“…Lu et al [ 22 ] solidified the waste slag of limestone generated in the project and revealed that the reason why the waste slag of limestone remolded by cement was inferior to that remolded by lime through XRD, SEM, particle size analysis, and other tests was the content of calcium hydroxide in the soil. Cai et al [ 23 ] analyzed and compared the freeze–thaw durability of active MgO carbonation and cement-solidified soil via indoor triaxial testing, and they used SEM for microscopic image analysis.…”

Section: Introductionmentioning

confidence: 99%

Curing Mechanisms of Polymeric Nano-Copolymer Subgrade

Shi,

Wang,

et al. 2023

Materials

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The mechanical properties of the subgrade have a significant impact on the service life and pavement performance of the superstructure of pavement. By adding admixtures and via other means to strengthen the adhesion between soil particles, the strength and stiffness of the soil can be improved to ensure the long-term stability of pavement structures. In this study, a mixture of polymer particles and nanomaterials was used as a curing agent to examine the curing mechanism and mechanical properties of subgrade soil. Using microscopic experiments, the strengthening mechanism of solidified soil was analyzed with scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier infrared spectroscopy (FTIR), and X-ray diffraction (XDR). The results showed that with the addition of the curing agent, small cementing substances on the surface of soil minerals filled the pores between minerals. At the same time, with an increase in the curing age, the colloidal particles in the soil increased, and some of them formed large aggregate structures that gradually covered the surface of the soil particles and minerals. By enhancing the cohesiveness and integrity between different particles, the overall structure of the soil became denser. Through pH tests, it was found that the age had a certain effect on the pH of solidified soil, but the effect was not obvious. Through the comparative analysis of elements in plain soil and solidified soil, it was found that no new chemical elements were produced in the solidified soil, indicating that the curing agent does not have negative impacts on the environment.

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“…Zhang [ 25 ] verified that the anionic polyacrylamide-modified bentonite reduced hydraulic conductivity from 3.91 × 10 −10 to 2.12 × 10 −11 m/s. A skeleton created by sand in the BS enhanced the structural durability of the impermeable layer, facilitating its long-term use [ 26 ]. The mechanism of impermeability has not yet been fully investigated.…”

Section: Introductionmentioning

confidence: 99%

A Study on the Impermeability of Nanodispersible Modified Bentonite Based on Colloidal Osmotic Pressure Mechanisms and the Adsorption of Harmful Substances

Zhang

Gong

et al. 2023

Nanomaterials

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With the growing demands of human beings, sanitary landfill, along with the increase in landfill depth and leachate water pressure, has put forward new and higher requirements for the impermeable layer. In particular, it is required to have a certain adsorption capacity of harmful substances from the perspective of environmental protection. Hence, the impermeability of polymer bentonite–sand mixtures (PBTS) at different water pressure and the adsorption properties of polymer bentonite (PBT) on contaminants were investigated through the modification of PBT using betaine compounded with sodium polyacrylate (SPA). It was found that the composite modification of betaine and SPA could reduce the average particle size of PBT dispersed in water (reduced to 106 nm from 201 nm) and enhance the swelling properties. As the content of SPA increased, the hydraulic conductivity of PBTS system decreases and the permeability resistance improves, while the resistance to external water pressure increases. It is proposed a concept of the potential of osmotic pressure in a constrained space to explain the impermeability mechanism of PBTS. The potential of osmotic pressure obtained by linear extrapolation of the trendline of colloidal osmotic pressure versus mass content of PBT could represent the external water pressure that the PBT resist. Additionally, the PBT also has a high adsorption capacity for both organic pollutants and heavy metal ions. The adsorption rate of PBT was up to 99.36% for phenol; up to 99.9% for methylene blue; and 99.89%, 99.9%, and 95.7% for low concentrations of Pb2+, Cd2+, and Hg+, respectively. This work is expected to provide strong technical support for the future development in the field of impermeability and removal of hazardous substances (organic and heavy metals).

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Effect of Sand Particle Size on Hydraulic-Mechanical Behavior of Bentonite-Sand Mixtures

Cited by 9 publications

References 37 publications

Effects of Freeze–Thaw Cycle on Permeability and Compression Properties of Aeolian Soil–Bentonite Mixture

Effects of Freeze–Thaw Cycle on Permeability and Compression Properties of Aeolian Soil–Bentonite Mixture

Curing Mechanisms of Polymeric Nano-Copolymer Subgrade

A Study on the Impermeability of Nanodispersible Modified Bentonite Based on Colloidal Osmotic Pressure Mechanisms and the Adsorption of Harmful Substances

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