Hydraulic properties of smectite rich clay controlled by hydraulic gradients and filter types

Al-Taie, Laith; Pusch, Roland; Knutsson, Sven

doi:10.1016/j.clay.2013.11.027

Cited by 14 publications

(4 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A displacement of particles, which are not directly involved in the load-carrying of specimen's fabric downward the flow direction, resulting in clogging of specimen's pores was proposed as a further possible reason for seepage-induced changes in the permeability [30]. In the study by Al-Taie et al [34], clogging of sintered filters by this mechanism was proposed as an alternative explanation for permeability decreases observed upon increases of hydraulic gradients above 1000 m/m in experiments with a smectite-rich clay and distilled water. However, in the infiltration tests of hydraulic gradients up to~64,000 m/m [29], no density changes along the profile of a bentonite specimen, which would provide evidence of such displacement, were found.…”

Section: Resultsmentioning

confidence: 99%

Swelling Pressure and Permeability of Compacted Bentonite from 10th Khutor Deposit (Russia)

2021

View full text Add to dashboard Cite

Bentonites from the 10th Khutor deposit (Republic of Khakassia, Russia) are considered a potential buffer material for isolation of radioactive waste in the crystalline rocks of Yeniseyskiy site (Krasnoyarskiy region). This study presents the results of a series of permeameter experiments with bentonite compacted to dry densities of 1.4, 1.6, and 1.8 g/cm3, saturated and permeated by the artificial groundwater from Yeniseyskiy Site. Permeation was conducted at hydraulic gradients of 180–80,000 m/m to simulate potential hydraulic conditions in the early post-closure phase of a deep geological repository (DGR). The respective swelling pressures of 0.8 ± 0.3, 2.2 ± 0.6, and 6.3 ± 0.3 MPa and permeabilities of (27 ± 15) × 10−20, (3.4 ± 0.8) × 10−20, and (0.96 ± 0.26) × 10−20 m2 were observed for the hydraulic gradient of 2000 m/m, which is recommended for the determination of undisturbed swelling pressures and permeabilities in permeameter experiments. Upon incremental increases in the hydraulic gradient, swelling pressures at all densities and permeability at the density of 1.8 g/cm3 remained unchanged, whereas permeabilities at 1.4 and 1.6 g/cm3 decreased overall by a factor of approximately 5 and 1.7, respectively. Seepage-induced consolidation and/or reorganisation of bentonite microstructure are considered possible reasons for these decreases.

show abstract

Section: Resultsmentioning

confidence: 99%

Swelling Pressure and Permeability of Compacted Bentonite from 10th Khutor Deposit (Russia)

2021

View full text Add to dashboard Cite

show abstract

“…This gradient causes less microstructural disturbance and gives more accurate conductivity data than testing under the 30 to 100 times higher gradients used by most other investigators (Al-Taie et al, 2014) (Figure 7).…”

Section: Hydraulic Conductivitymentioning

confidence: 93%

Holmehus clay — A Tertiary smectitic clay of potential use for isolation of hazardous waste

Pusch

Kasbohm²,

Hoang-Minh

et al. 2015

Engineering Geology

Self Cite

View full text Add to dashboard Cite

The Danish Tertiary Holmehus clay belongs to the series of illite-smectite mixed-layer clays in northern Europe and has a potential to serve as an effective engineered barrier for isolating hazardous waste. Mineralogical specification was made of the components illite/smectite mixed-layer and dioctahedral vermiculite/smectite mixedlayer structures. The lower content of expandable phase than of smectiterich clays like MX-80 gives somewhat higher hydraulic conductivity and somewhat lower swelling pressure but both are deemed suitable for isolating canisters with high-level radioactive waste in deep repositories for densities at water saturation of at least 1900 kg/m3. The lower swelling pressure, the potential of being chemically more stable, and the high buffer capacity by providing dissolved Si makes Holmehus clay a candidate for use in both deep and near-surface repositories. dioctahedral vermiculite. The acronyms "IS-ml" and "diVS-ml" refer to illite/smectite mixed-85 layer and dioctahedral vermiculite/smectite mixed-layer, respectively. 86Samples were milled to < 63 μm and dried at 40 °C before XRF measurement. Analysis 87 was carried out on KBr-pressed pellets using a wavelength dispersive Phillips PW 2404 X-ray Geotechnical experiments 111The geotechnical properties were determined by conducting oedometer tests for 112 evaluation of the hydraulic conductivity and swelling pressure for two types of porewater 113(distilled water and 3.5% CaCl 2 solution) and typical densities. (Table 1). Small amounts of chlorite and feldspars were also found as well as 121 traces of anatase, pyrite, gypsum and jarosite. 122The IS-ml phases were fully expandable to 17 Å spacing by ethylene glycol saturation 001/002-and 002/003-interferences, showed that the smectite layer-fraction of the IS-ml was 127 60 % and that the diVS-ml was 20-25%. Transmission electron microscopy (TEM) 131The two mixed layer phases in fraction < 2 µm were r characterized by two morphological forms: 132(i) xenomorphic flakes, probably products of diagenetic alteration; and (ii) laths with idiomorphic 133 ends (probably detrital material originating from weathered crust). Lath-like particles are 134 enriched in fraction <0.5 μm. 135The TEM-EDX analyses showed that the IS-ml structures make up 45 frequency-% and 136 the diVS-ml phases make up 15 frequency-% in Holmehus clay. The rest was found to consist of 137 quartz (18 frequency-%) and Fe-as well as Ti-phases. The content of smectite layers (S%) in IS-138 ml was 60% and for the diVS-ml was 30% ( (Table 2).

show abstract

“…From Classical Soil Mechanics, based on sedimentary soils formed in temperate regions, it is known that the velocity of percolation of a liquid in the soil can promote structural changes in the soil, with possible repercussions on its mechanical and hydraulic properties (Fox,1996;Kaoser et al, 2006;Ke & Takahashi, 2012, 2014Al-Taie et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Effects of Hydraulic Gradient Variation on the Structure and Strength of a Compacted Tropical Soil

Silva¹,

Pitanga²,

Silva³

et al. 2020

S&R

View full text Add to dashboard Cite

Tropical soils have been extensively studied to evaluate the technical feasibility of their application in hydraulic earthworks such as compacted clay barriers in landfills. In these earthworks, the water flow in the porous medium generates percolation forces that can promote structural changes in the soil, with possible deleterious repercussions on its mechanical and hydraulic properties. In this context and considering the geotechnical peculiarities of tropical soils, this research aimed to characterize the influence of the hydraulic gradient used in column percolation tests on the structure of a compacted tropical soil and, therefore, on its shear strength. Compacted test specimens were subjected to water percolation tests and then to direct shear tests. Thin sections were removed from the compacted layers for micromorphological analysis. The results showed that, statistically, at 5 % probability level, no significant variation in the overall mean shear strength and in the micromorphological features was found as a function of the applied hydraulic gradients. In general, the non-statistically significant change in soil structure also justifies the lack of significant variability on shear strength. The research highlights the importance of micromorphological analysis supported by statistics in understanding the structural aspects of compacted soils responsible for their engineering behaviors.

show abstract

Hydraulic properties of smectite rich clay controlled by hydraulic gradients and filter types

Cited by 14 publications

References 8 publications

Swelling Pressure and Permeability of Compacted Bentonite from 10th Khutor Deposit (Russia)

Swelling Pressure and Permeability of Compacted Bentonite from 10th Khutor Deposit (Russia)

Holmehus clay — A Tertiary smectitic clay of potential use for isolation of hazardous waste

Effects of Hydraulic Gradient Variation on the Structure and Strength of a Compacted Tropical Soil

Contact Info

Product

Resources

About