Water retention model for compacted bentonites

Dieudonné, Anne Catherine; Vecchia, Gabriele Della; Charlier, Robert

doi:10.1139/cgj-2016-0297

Cited by 69 publications

(42 citation statements)

References 41 publications

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“…The total suction (S u ) is equal to the sum of matric suction (p m ) and osmotic suction (p), according to the definition of soil suction by the International Society of Soil Science and others [23,52]. Water adsorption upon clay minerals at high suction levels and capillary retention at lower suction levels [10,48] are responsible for matric suction. Water adsorption is mainly governed by the physicochemistry of clay minerals and takes place in the intra-aggregate micropores in terms of electric double layers between the clay stacks [48].…”

Section: Wrc For Mx-80 Bentonitementioning

confidence: 99%

“…The macropore WRC is derived from Dieudonne et al [10], who proposed a model for the macropore water retention curve and calibrated it successfully against experimental results for MX-80 bentonite. Their approach is based on the following assumptions:…”

Section: Macropore Wrcmentioning

confidence: 99%

“…Based on the above assumptions, Dieudonné et al [10] fitted the van Genuchten equation to experimental data. The data points from those authors for compacted MX-80 bentonite at a dry density of 1.6 g/cm 3 are plotted as square dots in Fig.…”

Section: Macropore Wrcmentioning

confidence: 99%

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A dual-porosity model for the study of chemical effects on the swelling behaviour of MX-80 bentonite

Li¹,

Zheng

et al. 2019

Acta Geotech.

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Significant chemical influence on the swelling potential of MX-80 bentonite was observed during swelling tests where specimens were hydrated with highly concentrated brine. The maximum swelling pressure for specimens hydrated with brine was about 30% of the maximum swelling pressure for the same specimens hydrated with de-ionized water. The maximum swelling pressure was attained within tens of hours of brine infiltration and further decreased by half within a year. A fully coupled hydro-mechanical-chemical (HMC) dual-porosity model is proposed in this paper to interpret the swelling behaviour of MX-80 when infiltrated with brine. The dependence of hydraulic and mechanical properties on such factors as porosity, salinity and water content was investigated. A nonlinear elastic constitutive model was proposed to correlate the swelling pressure with the variation in the microporosity. The chemical effects on the mechanical behaviour were coupled at the micropore level. A number of relationships have been developed for MX-80, i.e. micropore permeability as a function of void ratio, water retention characteristics of micropores and macropores, micropore dependence on water content and the diffusion coefficients of the two types of pore structure. The proposed model was successful in reproducing both quantitatively and qualitatively the experimental results from two sets of infiltration experiments on compacted MX-80 bentonite.

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Section: Wrc For Mx-80 Bentonitementioning

confidence: 99%

Section: Macropore Wrcmentioning

confidence: 99%

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A dual-porosity model for the study of chemical effects on the swelling behaviour of MX-80 bentonite

Li¹,

Zheng

et al. 2019

Acta Geotech.

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“…Similar observations have been obtained by Romero and Vaunat (2000) and Romero et al (2011), who adopted double structure framework to interpret water retention behaviour. Similar approach has been chosen by Dieudonne et al (2017), who separately considered adsorbed water in the micropores and capillary water in the macropores. Gatabin et al (2016) attributed the difference in water retention curves of bentonite measured under confined and unconfined conditions to its microstructure.…”

Section: Introductionmentioning

confidence: 99%

Bentonite microstructure and saturation evolution in wetting–drying cycles evaluated using ESEM, MIP and WRC measurements

et al. 2019

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In this paper, microstructure of the Czech bentonite B75 was investigated by three methods: Water retention curve (WRC) measurements, mercury intrusion porosimetry (MIP) measurements and environmental scanning electron microscopy (ESEM) investigation. The experiments were performed on samples of various compaction levels (between 1.27 g/cm 3 and 1.90 g/cm 3) and at various suctions (between 3.3 MPa and 290 MPa) along both drying and wetting hydraulic paths. In the ESEM observations, target relative humidities (and thus total suctions) were imposed directly in the ESEM chamber to observe the effect of hydraulic path on the microstructure. Apart from the inter-lamellar pores, which are not accessible to the adopted experimental techniques, two pore families were identified: micropores and macropores. The transition pore size between the micropores and macropores was found to be suction dependent. The microporosity was practically insensitive to compaction and only largest micropores were sensitive to suction. Smaller macropores were sensitive to compaction only, whereas larger macropores were sensitive to both compaction and suction. We observed that during wetting from the as-compacted state the macropores remained completely dry up to very low values of suction, whereas micropores were found to be unsaturated up to the suctions between 10 MPa to 60 MPa. Both macropores and micropores contributed to sample volume changes during drying and wetting. While the microstructural volume change appeared to be reversible, macrostructure exhibited permanent deformation.

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“…Dependence of water retention behaviour on suction levels has been highlighted. In the high suction range, water retention is almost unaffected by dry density and volume constraint condition, while water retention in the low suction range is sensitive to variations in dry density and volume constraint condition (Delage et al, 1998;Agus, 2005;Villar, 2007;Seiphoori et al, 2014;Gatabin et al, 2016;Dieudonne et al, 2017). The water retention capacity has been shown to decrease with increasing temperature (Lloret et al, 2004;Tang & Cui, 2005;Imbert et al, 2005;Jacinto et al, 2009;Qin et al In the present study, an experimental investigation was performed to study chemical influences on water retention curves of compacted GMZ bentonite, which were determined by measuring suction of samples with different pore fluids including distilled water, sodium chloride solutions and calcium chloride solutions.…”

Section: Introductionmentioning

confidence: 99%

Chemical influence on water retention behaviour of compacted bentonite

Qin

Yang

Chen

2019

JGS Special Publication

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This present study investigated the chemical influence on the water retention curves of compacted GMZ bentonite. Sodium chloride solution and calcium chloride solution were mixed with the bentonite before compaction. Water retention curves were determined by measuring suctions with a the high-precision humidity sensor. The chemical influences on water retention curves were predominant in the suction range less than 70 MPa. In the suction range, an increasing of solution salinity resulted in an upward movement of water retention curve, i.e. an increasing of water retention capability of the bentonite. The solution type also had notable influence on the water retention behaviour. A higher water retention capability of the bentonite added with calcium chloride solution was observed compared to that with sodium chloride solution. In the suction range larger than 70 MPa, the influences of the solution type and salinity on the water retention behaviour were insignificant, and the water retention curves with different solutions were almost identical.

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Water retention model for compacted bentonites

Abstract: The water retention behaviour of compacted bentonites is strongly affected by multi-physical and multi-scale processes taking place in these materials. Experimental data have evidenced major effects of the material dry density, the imposed volume constraints and the soil fabric.

Cited by 69 publications

References 41 publications

A dual-porosity model for the study of chemical effects on the swelling behaviour of MX-80 bentonite

A dual-porosity model for the study of chemical effects on the swelling behaviour of MX-80 bentonite

Bentonite microstructure and saturation evolution in wetting–drying cycles evaluated using ESEM, MIP and WRC measurements

Chemical influence on water retention behaviour of compacted bentonite

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