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Ke Liu - One of the best experts on this subject based on the ideXlab platform.
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Moisture tension in fine-grained reconstituted soils at high Initial Water Contents
Acta Geotechnica, 2020Co-Authors: Wen-jing Sun, Yujun Cui, Zhenshun Hong, Han-lin Wang, Ke LiuAbstract:The reclamation of land filled with high Water Content dredged clays is an important geological and geo-environmental issue. When designing such reclaimed land, the yield behaviour during compression is of paramount importance because it conditions the compressibility of soil and thus the final ground settlement. Previous studies suggest a significant effect of Initial state of soils on their compression behaviour; in particular, the remoulded yield stress (identified when compressing reconstituted samples at high Initial Water Content) decreased with the increase in Initial Water Content. This phenomenon has been attributed to the effect of moisture tension. In fact, for a reconstituted soil at high Initial Water Content, non-destroyed aggregates may exist in microscopic level although the degree of saturation of soil reaches 100% in macroscopic level. These aggregates can give rise to the generation of negative Water pressure inside the aggregates, namely moisture tension. This moisture tension can greatly affect the mechanical behaviour of soil in the macroscopic level. With the destruction of aggregates, the moisture tension decreases. In order to verify this surmise, a series of experiments were conducted with moisture tension measurement on reconstituted Jossigny silt at three different Water Contents (1.0, 1.2 and 1.5 times the liquid limit). Meanwhile, mercury intrusion porosimetry (MIP) tests were conducted to analyse the macroscopic features. The test results proved the existence of moisture tension, and it decreased with increasing Water Content. When the aggregates are destructed completely, the moisture tension becomes zero. The non-intruded void ratio obtained from MIP tests was found to increase with decreasing Water Content, suggesting the destruction of aggregates by further hydration. Physically, the moisture tension corresponds to the Water absorption potential of aggregates or the potential changes of aggregates from metastable state to true stable state. These observations provide experimental evidence supporting the existence of the remoulded yield stress identified for saturated reconstituted soils.
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Moisture tension in fine-grained reconstituted soils at high Initial Water Contents
'Springer Science and Business Media LLC', 2020Co-Authors: Sun Wen-jing, Cui Yu-jun, Hong Zhen-shun, Wang Han-lin, Ke LiuAbstract:International audienceThe reclamation of land filled with high Water Content dredged clays is an important geological and geo-environmental issue. When designing such reclaimed land, the yield behaviour during compression is of paramount importance because it conditions the compressibility of soil and thus the final ground settlement. Previous studies suggest a significant effect of Initial state of soils on their compression behaviour; in particular, the remoulded yield stress (identified when compressing reconstituted samples at high Initial Water Content) decreased with the increase in Initial Water Content. This phenomenon has been attributed to the effect of moisture tension. In fact, for a reconstituted soil at high Initial Water Content, non-destroyed aggregates may exist in microscopic level although the degree of saturation of soil reaches 100% in macroscopic level. These aggregates can give rise to the generation of negative Water pressure inside the aggregates, namely moisture tension. This moisture tension can greatly affect the mechanical behaviour of soil in the macroscopic level. With the destruction of aggregates, the moisture tension decreases. In order to verify this surmise, a series of experiments were conducted with moisture tension measurement on reconstituted Jossigny silt at three different Water Contents (1.0, 1.2 and 1.5 times the liquid limit). Meanwhile, mercury intrusion porosimetry (MIP) tests were conducted to analyse the macroscopic features. The test results proved the existence of moisture tension, and it decreased with increasing Water Content. When the aggregates are destructed completely, the moisture tension becomes zero. The non-intruded void ratio obtained from MIP tests was found to increase with decreasing Water Content, suggesting the destruction of aggregates by further hydration. Physically, the moisture tension corresponds to the Water absorption potential of aggregates or the potential changes of aggregates from metastable state to true stable state. These observations provide experimental evidence supporting the existence of the remoulded yield stress identified for saturated reconstituted soils
Joao Mendes - One of the best experts on this subject based on the ideXlab platform.
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influence of Initial Water Content on the mechanical behavior of unsaturated sandy clay soil
International Journal of Geomechanics, 2016Co-Authors: Joao Mendes, D G TollAbstract:AbstractThe mechanical behavior of a sandy clay soil was investigated by a series of constant Water Content triaxial tests on unsaturated samples with suction measurements. The tests were carried out in double-cell triaxial cells on compacted samples and also on samples wetted and dried from the as-compacted conditions. A series of tests on saturated samples was also performed to provide a reference state for the unsaturated tests. Because the specimens were at high degrees of saturation (generally >80%), calculations based on effective stress showed a reasonable interpretation of the data for the critical state parameters M and λ. However, the intercept of the critical state line in the ν-axis (Γ) differed and increased with an increase in Water Content (at compaction). The data were also analyzed using the Bishop stress (p*) approach, and a better fitting was achieved in the stress plane, where it was possible to define a unique critical state line, where M was 0.91. However, in the ν-p* plane, differen...
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influence of Initial Water Content on the Water retention behaviour of a sandy clay soil
18th International Conference on Soil Mechanics and Geotechnical Engineering ICSMGE 2013, 2013Co-Authors: Joao Mendes, D G TollAbstract:In order to model the impact of climate changes on the infrastructure for the built environment, such as embankments and cuttings, an understanding of the Water retention behaviour is required. To this end, a series of filter paper tests were carried out on remoulded samples of a sandy clay material of medium plasticity. The soil samples were prepared with different Initial Water Contents and dynamically compacted. Filter paper tests were performed to determine the soil Water retention curve (SWRC) from a saturated state. Other subsamples were wetted or dried to reach different Water Contents for testing. The obtained results were then compared with the SWRC. The drying tests showed typical behaviour of scanning curves, however the wetting curves showed untypical behaviour, where the curves appeared to overlap each other with no clear pattern. The observed behaviour from laboratory samples can be extrapolated to field conditions, where future climate change will have a major impact on the Water retention behaviour on earth structures, which will have implications for the geo-mechanical behaviour.
Yujun Cui - One of the best experts on this subject based on the ideXlab platform.
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influence of Initial Water Content on unsaturated shear strength of compacted gaomiaozi gmz bentonite
Canadian Geotechnical Journal, 2021Co-Authors: N F Zhao, Qiong Wang, Bao Chen, Yujun CuiAbstract:This paper presents an experimental study on the influence of Initial Water Content on unsaturated shear strength of compacted bentonite. Isotropic loading and triaxial shear tests were conducted o...
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Moisture tension in fine-grained reconstituted soils at high Initial Water Contents
Acta Geotechnica, 2020Co-Authors: Wen-jing Sun, Yujun Cui, Zhenshun Hong, Han-lin Wang, Ke LiuAbstract:The reclamation of land filled with high Water Content dredged clays is an important geological and geo-environmental issue. When designing such reclaimed land, the yield behaviour during compression is of paramount importance because it conditions the compressibility of soil and thus the final ground settlement. Previous studies suggest a significant effect of Initial state of soils on their compression behaviour; in particular, the remoulded yield stress (identified when compressing reconstituted samples at high Initial Water Content) decreased with the increase in Initial Water Content. This phenomenon has been attributed to the effect of moisture tension. In fact, for a reconstituted soil at high Initial Water Content, non-destroyed aggregates may exist in microscopic level although the degree of saturation of soil reaches 100% in macroscopic level. These aggregates can give rise to the generation of negative Water pressure inside the aggregates, namely moisture tension. This moisture tension can greatly affect the mechanical behaviour of soil in the macroscopic level. With the destruction of aggregates, the moisture tension decreases. In order to verify this surmise, a series of experiments were conducted with moisture tension measurement on reconstituted Jossigny silt at three different Water Contents (1.0, 1.2 and 1.5 times the liquid limit). Meanwhile, mercury intrusion porosimetry (MIP) tests were conducted to analyse the macroscopic features. The test results proved the existence of moisture tension, and it decreased with increasing Water Content. When the aggregates are destructed completely, the moisture tension becomes zero. The non-intruded void ratio obtained from MIP tests was found to increase with decreasing Water Content, suggesting the destruction of aggregates by further hydration. Physically, the moisture tension corresponds to the Water absorption potential of aggregates or the potential changes of aggregates from metastable state to true stable state. These observations provide experimental evidence supporting the existence of the remoulded yield stress identified for saturated reconstituted soils.
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effect of Initial Water Content on undrained shear behaviour of reconstituted clays
Geotechnique, 2013Co-Authors: Zhenshun Hong, Yujun Cui, Xia Bian, Yufeng Gao, Lingling ZengAbstract:Isotropically consolidated undrained triaxial compression shear tests were performed on three reconstituted clays to investigate the effect of Initial Water Content w0 on undrained strength behaviour. The values of w0 were adjusted within the range of 1·0–2·0 times the liquid limit. The predominant clay mineral is identified as illite for the considered clays, based on a semi-quantitative analysis of the X-ray diffraction patterns. The laboratory tests show that the stress–strain curve in terms of deviator stress against axial strain and the effective stress path in terms of deviator stress against effective mean stress are significantly affected by w0. The undrained strength ratio R*su, defined as the ratio of the undrained shear strength S*u to the isotropic consolidation stress, varies with w0 within a wide spectrum, ranging from 0·28 to 0·60 for the three reconstituted clays investigated. The relationship between void index Iv and S*u changes with R*su, and becomes identical to the intrinsic strength ...
Wim E Hennink - One of the best experts on this subject based on the ideXlab platform.
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release of recombinant human interleukin 2 from dextran based hydrogels
Journal of Controlled Release, 2002Co-Authors: J A Cadee, C J De Groot, Wim Jiskoot, Den W Otter, Wim E HenninkAbstract:Abstract In this study, the release of recombinant human interleukin-2 (rhIL-2) from methacrylated dextran (dex-MA) and (lactate-)hydroxyethyl methacrylated dextran (dex-(lactate-)HEMA) hydrogels with varying crosslink density was investigated. Hydrogels derived from dex-MA are stable under physiological conditions (pH 7 and 37°C), whereas dex-HEMA and dex-lactate-HEMA hydrogels degrade due to the presence of hydrolytically sensitive esters in the crosslinks of the gels. The protein release profiles both the non-degradable and degradable dextran-based hydrogels showed that with increasing crosslink density of the gel, the release of rhIL-2 decreases. From dex-MA hydrogels with an Initial Water Content above 70%, the rhIL-2 release followed Fickian diffusion, whereas from gels with an Initial Water Content of 70% or lower the protein was fully entrapped in the hydrogel meshes. In contrast with non-degradable dex-MA hydrogels, degradable dex-lactate-HEMA gels with comparable network characteristics (degree of methacrylate substitution and Initial Water Content) showed an almost zero-order, degradation controlled release of rhIL-2 in a time period of 5–15 days. This paper demonstrates that the release of rhIL-2 from non-degradable dex-MA and degradable dex-lactate-HEMA gels can be modulated by the crosslink density and/or the degradation characteristics of the hydrogel. Importantly, rhIL-2 was mainly released as monomer from the hydrogels and with good retention of its biological activity.
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degradation and release behavior of dextran based hydrogels
Macromolecules, 1997Co-Authors: W N E Van Dijkwolthuis, J A M Hoogeboom, M J Van Steenbergen, S K Y Tsang, Wim E HenninkAbstract:Dextran hydrogels were prepared by radical polymerization of aqueous solutions of glycidyl methacrylate-derivatized dextran (dex-MA), hydroxyethyl methacrylate-derivatized dextran (dex-HEMA), and HEMA−oligolactate-derivatized dextran (dex-lactateHEMA), using potassium peroxydisulfate and N,N,N‘,N‘-tetramethylethylenediamine (TEMED) as the initiating system. Dex-MA hydrogels only degraded under extreme conditions (100 °C, pH 1−3), whereas hydrogels derived from dex-HEMA or dex-lactateHEMA degraded fully at pH 7.2 and 37 °C, due to hydrolysis of the lactate and/or carbonate esters in the cross-links. The degradation time of these gels can be tailored from 2 days to more than 2 months by varying the nature of the spacer, the degree of substitution1 of dextran (DS), and the Initial Water Content of the hydrogels. The release kinetics of a model protein, Immunoglobulin G, from dex-(lactate)HEMA hydrogels were investigated and shown to be dependent on both the DS and the Initial Water Content of the gel. Under ...
D G Toll - One of the best experts on this subject based on the ideXlab platform.
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influence of Initial Water Content on the mechanical behavior of unsaturated sandy clay soil
International Journal of Geomechanics, 2016Co-Authors: Joao Mendes, D G TollAbstract:AbstractThe mechanical behavior of a sandy clay soil was investigated by a series of constant Water Content triaxial tests on unsaturated samples with suction measurements. The tests were carried out in double-cell triaxial cells on compacted samples and also on samples wetted and dried from the as-compacted conditions. A series of tests on saturated samples was also performed to provide a reference state for the unsaturated tests. Because the specimens were at high degrees of saturation (generally >80%), calculations based on effective stress showed a reasonable interpretation of the data for the critical state parameters M and λ. However, the intercept of the critical state line in the ν-axis (Γ) differed and increased with an increase in Water Content (at compaction). The data were also analyzed using the Bishop stress (p*) approach, and a better fitting was achieved in the stress plane, where it was possible to define a unique critical state line, where M was 0.91. However, in the ν-p* plane, differen...
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influence of Initial Water Content on the Water retention behaviour of a sandy clay soil
18th International Conference on Soil Mechanics and Geotechnical Engineering ICSMGE 2013, 2013Co-Authors: Joao Mendes, D G TollAbstract:In order to model the impact of climate changes on the infrastructure for the built environment, such as embankments and cuttings, an understanding of the Water retention behaviour is required. To this end, a series of filter paper tests were carried out on remoulded samples of a sandy clay material of medium plasticity. The soil samples were prepared with different Initial Water Contents and dynamically compacted. Filter paper tests were performed to determine the soil Water retention curve (SWRC) from a saturated state. Other subsamples were wetted or dried to reach different Water Contents for testing. The obtained results were then compared with the SWRC. The drying tests showed typical behaviour of scanning curves, however the wetting curves showed untypical behaviour, where the curves appeared to overlap each other with no clear pattern. The observed behaviour from laboratory samples can be extrapolated to field conditions, where future climate change will have a major impact on the Water retention behaviour on earth structures, which will have implications for the geo-mechanical behaviour.