Effect of solute concentration on the volume change and shear strength of compacted natural expansive clay

Elkady, Tamer Y.; Al-Mahbashi, Ahmed M.

doi:10.1007/s12665-017-6825-0

Cited by 27 publications

(8 citation statements)

References 36 publications

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“…This showed that SLS solution changed the particle size composition of expansive soil, i.e., increased the content of the coarse particle group and decreased water sensitivity, hydrophilicity, and specific surface area of soil. Clay particles tended to flocculate at high salt concentrations [27]. Flocculation could cause decreased specific surface area, free swell, and swell pressure [28].…”

Section: Resultsmentioning

confidence: 99%

“…When the physical and chemical environments of pore solution changed, due to the interaction of particles and pore solution, the particle arrangement, structural characteristics, and pore water occurrence state of soil were changed, thus changing its macro physical and mechanical properties. At clay particle scale, diffused double layer dictated the hydraulic and mechanical behaviors of clay [27]. Variation of pore solution environment in soil disturbed the original balance of soil particles at microscopic scale but changed soil strength at macroscopic scale.…”

Section: Shear Strengthmentioning

confidence: 99%

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The Effects of Salt-Lake Salt Solution on the Strength of Expansive Soil

Zhang

2022

Geofluids

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Expansive soils are widely distributed and often cause serious damage to structures. Hanzhong expansive soil and Yulin salt-lake solution were adopted to investigate the effect of salt-lake salt solution on the strength of expansive soil. Expansive soils modified with salt-lake salt solutions with different concentrations (0.1, 0.5, and 1.0 mol/L) were evaluated by X-ray diffraction (XRD), Atterberg limit, free swelling, no load swelling ratio, and triaxial compression tests. The improved expansive soil research using salt-lake salt solution was carried out based on the macroscopic mechanical characteristics. Test results showed that the addition of salt-lake solution effectively inhibited the expansibility of soil. With the increase of the concentration of salt-lake solution, liquid limit, plastic limit, plastic index, free expansion rate, no load swelling, cohesion, and internal friction angle of expansive soil were decreased in varying degrees, and stress-strain relationship curve gradually showed strain softening trend. The reason for the above results was believed to be that salt-lake salt solution reduced the force between particles on shear surface and reduced mutual hindrance.

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Section: Resultsmentioning

confidence: 99%

Section: Shear Strengthmentioning

confidence: 99%

The Effects of Salt-Lake Salt Solution on the Strength of Expansive Soil

Zhang

2022

Geofluids

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“…According to the Gouy-Chapman theory about the changes in the diffuse double layer (DDL) [8,[39][40][41][42][43], previous studies on clay behaviour state that the volume changes of clays due to osmotic and diffusive phenomena arise from variations of the chemical composition of pore waters. Specifically, the DDL thickness increases with the decrease of the solution concentration and the charge of cations, and the increase of the hydrated cations radius.…”

Section: The Energy Of the System And The Swellingmentioning

confidence: 99%

Squeezed Interstitial Water and Soil Properties in Pleistocene Blue Clays under Different Natural Environments

et al. 2018

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Studies dating almost a century relate clay properties with the structure of the diffuse double layer (DDL), where the charged surfaces of clay crystal behave like an electric capacitor, whose dielectric is the interstitial fluid. The intensity of the inner electric field relates to the concentration and type of ions in the DDL. Other important implications of the model are less stressed: this part of the clay soil system, energetically speaking, is conservative. External contribution of energy, work of overburden or sun driven capillarity and long exposure to border low salinity waters can modify the concentration of pore-waters, thus affecting the DDL geometry, with electric field and energy storage variations. The study of clay soils coming from various natural geomorphological and hydrogeological contexts, determining a different salinity of interacting groundwater, shows how the clay interaction with freely circulating waters at the boundaries produces alterations in the native pore water salinity, and, at the nano-scale, variations of electric field and stored energy from external work. The swelling and the shrinkage of clay soil with their volumetric and geotechnical implications should be regarded as variations of the electrostatic and mechanical energy of the system. The study is based on tests on natural clay soil samples coming from a formation of stiff blue clays, widespread in southern Italy. Geotechnical identification and oedometer tests have been performed, and pore waters squeezed out from the specimens have been analyzed. Tested samples have similar grain size, clay fraction and plasticity; sorted according to the classified geomorphological/hydrogeological contexts, they highlight good correlations among dry density, mechanical work performed in selected stages of the oedometric test, swelling and non-swelling behaviour, and electrical conductivity of the squeezed pore waters. The work performed for swelling and non-swelling samples shows well-defined differences; this endorse the relevance of pore-water salinity in determining the volumetric state of clay soils under overburden and specific hydrogeological border conditions, which together define a specific energetic state.

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“…In summary, many researchers paid attention on the salinity, moisture content and micro-structure effects on mechanical properties of different soils (Loret et al, 2002;Debora and Miller, 2006;Koniorczyk and Gawin, 2008;Zhang et al, 2016;Elkady and Al-Mahbashi, 2017;Jabar and Rasul, 2017;Sato and Hattanji, 2018;He et al, 2020;Wang et al, 2020). While, few studies focus on the response of compression behavior of undisturbed loess and remolded loess to the environmental humidity change and saline water intrusion in the northwest arid and semi-arid areas.…”

Section: Introductionmentioning

confidence: 99%

The Compression Behavior of Undisturbed and Compacted Loess Under the Controlling of Total Suction and Injected Solutions

Zhang

Lan

et al. 2022

Front. Earth Sci.

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Thousands of square kilometers of habitable land have been created on the Loess Plateau in China. In arid and semi-arid area of Northwest China, the mechanical behavior of structural loess is sensitive to water intrusion and human engineering activities. Meanwhile, the higher water salinity in loess and seasonal variation of ambient humidity are common in this area. Due to different physical and mechanical properties of natural and compacted loess, the impacts of ambient humidity and saline water migration on their deformation are still unclear. This paper developed an oedometer test to investigate the compression behavior of natural and compacted loess under environmental humidity (represented by total suction Ψ) and injection water salinity (represented by osmotic suction Ψπ) changing. The results showed that the void ratio variation Δe of compacted loess (the dry density is 1.8 g/m3) under the impact of total suctions (from 14.01 to 146.23 MPa) and salinities of injected solution (0.17 mol/L NaCl, 0.29 mol/L Na2SO4 and distilled water) were under 0.01. The variation of void ratio for undisturbed loess increased about 8 times with 10 times decreasing of total suction, which was corresponding to the increase of relative humidity (RH). In the stage of solution injection, the deformation of undisturbed loess increased with the Ψ-Ψπ increasing, and the differences between different samples reached to nearly 20 times. The mechanism was that the salt inside undisturbed loess would deliquescence when the RH was higher than DRH (Deliquescence Relative Humidity), and the natural structure collapsed. The compression index Cc of samples generally decreased with Ψ-Ψπ, and the compressibility of undisturbed loess was higher. The swelling indices Cs of samples slightly decreased with Ψ-Ψπ, but the variation was not significant. The strain-stress relationships of loess can be well described by Duncan-Chang constitutive model. Interestingly, the difference of initial deformation modulus ΔEs of two loesses, which represented the structural compression under the coupling of total suction and osmotic suction, linearly related to the Ψ-Ψπ. The Δεmax between the structural loess and compacted loess exponential increased with Ψ-Ψπ. In the engineering practice, the humidity and saline water intrusion should be considered in the long-term behavior of loess in shallow layer.

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Effect of solute concentration on the volume change and shear strength of compacted natural expansive clay

Cited by 27 publications

References 36 publications

The Effects of Salt-Lake Salt Solution on the Strength of Expansive Soil

The Effects of Salt-Lake Salt Solution on the Strength of Expansive Soil

Squeezed Interstitial Water and Soil Properties in Pleistocene Blue Clays under Different Natural Environments

The Compression Behavior of Undisturbed and Compacted Loess Under the Controlling of Total Suction and Injected Solutions

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