Comparison of the hydrogeochemical and mechanical behaviours of compacted bentonite using different conceptual approaches

Yustres, Ángel; Jenni, Andreas; Asensio, Laura; Pintado, Xavier; Koskinen, Kari; Navarro, Vicente; Wersin, Paul

doi:10.1016/j.clay.2017.03.006

Cited by 17 publications

(7 citation statements)

References 60 publications

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“…Several studies underline the importance of mineralogical properties of clays and of pore water chemical composition in determining their geotechnical behaviour [1][2][3]. Just a few of these studies deal with the clay behaviour in relation to the variation of the chemical composition and salt content of pore fluids.…”

Section: Clay Geotechnical Behaviour Related To Pore Fluid Characterimentioning

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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Section: Clay Geotechnical Behaviour Related To Pore Fluid Characterimentioning

confidence: 99%

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

et al. 2018

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“…We tested in one or another way all of the potential applications mentioned above and are actively pursuing chemicophysical coupling phenomena, experimentally and by modelling approaches [11,12]. Some select details are addressed in the technical description below.…”

Section: Properties and Processesmentioning

confidence: 99%

Advective Displacement Method for the Characterisation of Pore Water Chemistry and Transport Properties in Claystone

Mäder

2018

Geofluids

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The advective displacement method applies large hydraulic gradients to a confined rock core sample to yield small aliquots of the preserved in situ pore water, applicable to aquitard rocks with hydraulic conductivities as low as 10 −14 m/s. Examples from argillaceous rocks indicate that only minor artefacts are induced and that analytical methods optimized for small aliquots provide a comprehensive chemical and isotopic characterisation. Multicomponent transport properties are derived from extending experimental time and using a traced artificial pore water for injection. Examples include quantification of the anion exclusion effect that can even resolve a small difference between transport properties for chloride and bromide in claystone. Controls by mineral saturation and cation exchange processes are also constrained by data from this approach. Technical details are provided for construction, material selection, components, sensors, and analytical issues.

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“…[8] stated that the ideal of compressive strength of green sand mouldis between 0-1.0kg/cm2. Therefore, the four specimenscan be considered of having an ideal compressive strength (0> 0.0073-0.0083 <1 kg/cm2) [9].…”

Section: A Compression Testing On the Moulding Sandmentioning

confidence: 99%

Formula of Moulding Sand, Bentonite and Portland Cement toImprove The Quality of Al-Si Cast Alloy

Andoko

Puspitasari

Permanasari

et al. 2017

JMEST

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A binder is any material used to strengthen the bonding of moulding sand grains. The primary function of the binder is to hold the moulding sand and other materialstogether to produce high-quality casts. In this study, there were four binder compositions being tested, i.e. 5% bentonite + 5% Portland cement, 4% bentonite + 6% Portland cement, 6% bentonite + 4% Portland cement, and 7% bentonite + 3% Portland cement. Each specimen was measured for its compressive strength, shear strength, tensile strength and permeability. The highest compressive strength was obtained fromthe specimen composed of 6% bentonite+ 4% Portland cement. The highest shear strength was obtained from the moulding sand with 7% bentonite+ 3%Portland cement. The highest tensile strength was obtained fromthe specimen contained 5% bentonite+ 5% Portland cement. The specimen composed of 5% bentonite + 5% Portland cement had the lowest permeability of 131 ml/min, while that of 6% bentonite + 4% Portland cement had the highest permeability of 176 ml/min..

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Comparison of the hydrogeochemical and mechanical behaviours of compacted bentonite using different conceptual approaches

Cited by 17 publications

References 60 publications

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

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

Advective Displacement Method for the Characterisation of Pore Water Chemistry and Transport Properties in Claystone

Formula of Moulding Sand, Bentonite and Portland Cement toImprove The Quality of Al-Si Cast Alloy

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