The Experts below are selected from a list of 61422 Experts worldwide ranked by ideXlab platform
Fusheng Zha - One of the best experts on this subject based on the ideXlab platform.
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Hydraulic Conductivity and strength of foamed cement-stabilized marine clay
Construction and Building Materials, 2019Co-Authors: Yongfeng Deng, Yu-jun Cui, Xiaopei Zheng, Zhenping Zhao, Yonggui Chen, Fusheng ZhaAbstract:In traditional soft ground improvement of cement stabilized columns, strength was paid more attention than Hydraulic Conductivity, but the latter can improve the settlement uniformity and long term safety. This study introduced the pore-making technology referring the foaming concrete/mortar in an attempt to improve the Hydraulic Conductivity of the stabilized marine clays. The flexible wall permeameter and unconfined compressive strength (UCS) tests were conducted to depict the macro behaviour, and then the mercury intrusion porosimetry (MIP) tests and scanning electron microscopy (SEM) tests were performed to clarify the micro-structures. The Hydraulic Conductivity of foamed cement-stabilized marine clay at a given cement ratio (20%–50%) and density (900–1400 kg/m3) was found to be approximately 100–1000 times of that of (cement stabilized) clays without foaming, whereas the strength decreased only by 2–4 times. Microstructure investigation indicated that the Hydraulic Conductivity of foamed cement-stabilized marine clays was mainly dominated by the macro pore volume (>1 μm). Furthermore, a greater cement ratio and more active metakaolin additives enable developing an innovative material for columns that satisfy both the strength and Hydraulic Conductivity requirement.
Yongfeng Deng - One of the best experts on this subject based on the ideXlab platform.
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Hydraulic Conductivity and strength of foamed cement-stabilized marine clay
Construction and Building Materials, 2019Co-Authors: Yongfeng Deng, Yu-jun Cui, Xiaopei Zheng, Zhenping Zhao, Yonggui Chen, Fusheng ZhaAbstract:In traditional soft ground improvement of cement stabilized columns, strength was paid more attention than Hydraulic Conductivity, but the latter can improve the settlement uniformity and long term safety. This study introduced the pore-making technology referring the foaming concrete/mortar in an attempt to improve the Hydraulic Conductivity of the stabilized marine clays. The flexible wall permeameter and unconfined compressive strength (UCS) tests were conducted to depict the macro behaviour, and then the mercury intrusion porosimetry (MIP) tests and scanning electron microscopy (SEM) tests were performed to clarify the micro-structures. The Hydraulic Conductivity of foamed cement-stabilized marine clay at a given cement ratio (20%–50%) and density (900–1400 kg/m3) was found to be approximately 100–1000 times of that of (cement stabilized) clays without foaming, whereas the strength decreased only by 2–4 times. Microstructure investigation indicated that the Hydraulic Conductivity of foamed cement-stabilized marine clays was mainly dominated by the macro pore volume (>1 μm). Furthermore, a greater cement ratio and more active metakaolin additives enable developing an innovative material for columns that satisfy both the strength and Hydraulic Conductivity requirement.
Craig H Benson - One of the best experts on this subject based on the ideXlab platform.
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variability of saturated Hydraulic Conductivity measurements made using a flexible wall permeameter
Geotechnical Testing Journal, 2016Co-Authors: Craig H Benson, Nazli YesillerAbstract:A study was conducted following the procedures in ASTM E691-14 (Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method) to develop a precision statement for Hydraulic Conductivity measurement of fine-grained soils using Method C (falling head, rising tailwater elevation) of ASTM D5084-10 (Standard Test Methods for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter). Twelve laboratories conducted tests on three replicate specimens of three fine-grained soils (9 specimens total per laboratory) from the ASTM Reference Soils Program: Soil ML (silt), Soil CL (low plasticity clay), and Soil CH (high plasticity clay). The data indicated that the measurement variability for Hydraulic Conductivity is modest but not negligible, and probably contributes to the spatial variability reported in past studies of Hydraulic Conductivity. No systematic relationships were observed between variability in Hydraulic Conductivity and testing time (consolidation, permeation), backpressure, B-coefficient achieved at end of consolidation, compliance with the termination criteria, or specimen compaction conditions. Many laboratories did not comply with the test standard or the supplemental instructions, which may indicate that greater oversight of geotechnical laboratories is needed via accreditation and auditing programs. Analysis of the data indicate that Hydraulic Conductivity can be measured using Method C of ASTM D5084 within a factor of 2 for the 10–6 cm/s range, a factor of 1.5 for the 10–8 cm/s range, and a factor of 4 for the 10–9 cm/s range.
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Hydraulic Conductivity of geosynthetic clay liners to synthetic coal combustion product leachates
Geo-Congress 2014, 2014Co-Authors: Jiannan Chen, Craig H Benson, William J Likos, Sabrina L Bradshaw, Tuncer B EdilAbstract:Experiments were conducted to evaluate whether coal combustion product (CCP) leachates adversely affect the Hydraulic Conductivity of geosynthetic clay liners (GCLs). Chemical properties of CCP leachates were compiled based on a nationwide survey of CCP disposal facilities. Five synthetic leachates were selected from this database to represent a range of conditions encountered in CCP disposal facilities: typical CCP leachate, strongly divalent cation fly ash leachate, flue gas desulfurization (FGD) residual leachate, high ionic strength ash leachate, and trona ash leachate. Five GCLs were tested: two conventional Na-bentonite GCLs, two polymer-modified bentonite GCLs, and one bentonite polymer composite (BPC). Hydraulic Conductivity tests were conducted on non-prehydrated GCLs using flexible-wall permeameters. GCLs with Na-bentonite had high Hydraulic Conductivity (>10 m/s) to trona leachate, whereas the Hydraulic Conductivity of GCLs with polymer-modified bentonite was variable, ranging from 10 to 10 m/s. For the typical CCP, high ionic strength, FGD, and strongly divalent cation leachates, GCLs with Na-bentonite had moderate to high Hydraulic Conductivity (10 to 10 m/s). GCLs with polymer-modified bentonite had lower Hydraulic Conductivity (10 to 10 9 m/s) to FGD and strongly divalent cation leachates, and a wide range of Hydraulic conductivities to high ionic strength leachate (10 to 10 m/s). All of the GCLs had low Hydraulic Conductivity (<10 m/s) to DI water. GCLs with BPC had very low Hydraulic Conductivity (< 10 m/s) to all leachates.
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Hydraulic Conductivity of geosynthetic clay liners exhumed from landfill final covers
Journal of Geotechnical and Geoenvironmental Engineering, 2007Co-Authors: Stephen R Meer, Craig H BensonAbstract:Samples of geosynthetic clay liners (GCLs) from four landfill covers were tested for water content, swell index, Hydraulic Conductivity, and exchangeable cations. Exchange of Ca and Mg for Na occurred in all of the exhumed GCLs, and the bentonite had a swell index similar to that for Ca or Mg bentonite. Hydraulic conductivities of the GCLs varied over 5 orders of magnitude regardless of cover soil thickness or presence of a geomembrane. Hydraulic Conductivity was strongly related to the water content at the time of sampling. Controlled desiccation and rehydration of exhumed GCLs that had low Hydraulic Conductivity ( 10−9 to 10−7 cm∕s) resulted in increases in Hydraulic Conductivity of 1.5–4 orders of magnitude, even with overburden pressure simulating a 1-m -thick cover. Comparison of these data with other data from the United States and Europe indicates that exchange of Ca and/or Mg for Na is likely to occur in the field unless the overlying cover soil is sodic (sodium rich). The comparison also shows th...
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saturated Hydraulic Conductivity of compacted recycled asphalt pavement
Geotechnical Testing Journal, 2005Co-Authors: Bert D Trzebiatowski, Craig H BensonAbstract:Tests were conducted to determine the saturated Hydraulic Conductivity of three recycled asphalt pavement (RAP) materials being used as base course aggregate for pavement construction. Comparative tests were also conducted on a compacted crushed rock aggregate (Lodi gravel) that is used for base course in Wisconsin. All four are granular materials. The RAPs have saturated Hydraulic conductivities ranging from 2.4 × 10−5 to 9.0 × 10−5 m/s when compacted with standard Proctor effort and from 4.5 × 10−8 to 1.7 × 10−6 m/s when compacted with modified Proctor effort. The Lodi gravel is less permeable, having saturated Hydraulic conductivities of 5.8 × 10−7 m/s (standard Proctor effort) and 2.4 × 10−9 m/s (modified Proctor effort). Three conventional methods of predicting the saturated Hydraulic Conductivity of coarse-grained soils were evaluated in terms of their ability to predict the saturated Hydraulic Conductivity of RAP: Hazen's equation, Kenney's equation, and the Kozeny-Carmen equation. Each of these equations overpredict the Hydraulic Conductivity of RAP. Two empirical equations to predict the Hydraulic Conductivity of RAP were developed from the saturated Hydraulic Conductivity data. The empirical equations were found to work well for RAP as well as the Lodi gravel. However, the empirical equations are based on a small data set. Updating of the equations is encouraged as more data become available.
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Long-term Hydraulic Conductivity of a geosynthetic clay liner permeated with inorganic salt solutions
Journal of Geotechnical and Geoenvironmental Engineering, 2005Co-Authors: Craig H Benson, Charles D Shackelford, Jae-myung Lee, Tuncer B EdilAbstract:Hydraulic Conductivity tests were conducted on a geosynthetic clay liner (GCL) for more than 2.5 years and as many as 686 pore volumes of flow (PVF) using single-species salt solutions (NaCl, KCl, or Ca Cl2 ) to (1) evaluate how the long-term Hydraulic Conductivity ( KL ) is affected by cation concentration and valence and (2) demonstrate the relevance and importance of termination criteria when measuring Hydraulic Conductivity of GCLs to salt solutions. Permeation with Ca Cl2 solutions resulted in an increase in the Hydraulic Conductivity of 1 order of magnitude or more. The rate at which these changes occurred depended on concentration, with slower changes (years and hundreds of PVF) occurring for weaker solutions. In contrast, permeation with 100 mM NaCl or KCl solutions or de-ionized (DI) water resulted in no appreciable change in Hydraulic Conductivity, regardless of the duration of permeation or number of pore volumes of flow. Hydraulic conductivities determined in accordance with ASTM D 5084 and D ...
Yu-jun Cui - One of the best experts on this subject based on the ideXlab platform.
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Hydraulic Conductivity of reconstituted clays based on intrinsic compression
Geotechnique, 2020Co-Authors: Ling-ling Zeng, Yuan-qiang Cai, Yu-jun Cui, Zhen-shun HongAbstract:A series of one-dimensional incremental load consolidation–Hydraulic Conductivity tests was performed on reconstituted clays. Based on these tests, together with the test data compiled from the literature, the quantitative interrelation between the variation of Hydraulic Conductivity in the vertical direction with void ratio and the compression behaviour is established. It is found that the Hydraulic Conductivity in the vertical direction can be expressed as a function of void index, initial void ratio and void ratio at the liquid limit. The effects of initial void ratio and void index on Hydraulic Conductivity in the vertical direction for a given clay with a given void ratio at the liquid limit can be comprehensively attributed to the effect of void ratio on Hydraulic Conductivity in the vertical direction. These two findings introduce the point that the Hydraulic Conductivity in the vertical direction is a function of void ratio and void ratio at the liquid limit. Empirical equations are proposed to determine the Hydraulic Conductivity in the vertical direction using void ratio and void ratio at the liquid limit or using effective vertical stress, initial void ratio and void ratio at the liquid limit. These two empirical equations are correlated based on the concept of intrinsic compression.
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Hydraulic Conductivity and strength of foamed cement-stabilized marine clay
Construction and Building Materials, 2019Co-Authors: Yongfeng Deng, Yu-jun Cui, Xiaopei Zheng, Zhenping Zhao, Yonggui Chen, Fusheng ZhaAbstract:In traditional soft ground improvement of cement stabilized columns, strength was paid more attention than Hydraulic Conductivity, but the latter can improve the settlement uniformity and long term safety. This study introduced the pore-making technology referring the foaming concrete/mortar in an attempt to improve the Hydraulic Conductivity of the stabilized marine clays. The flexible wall permeameter and unconfined compressive strength (UCS) tests were conducted to depict the macro behaviour, and then the mercury intrusion porosimetry (MIP) tests and scanning electron microscopy (SEM) tests were performed to clarify the micro-structures. The Hydraulic Conductivity of foamed cement-stabilized marine clay at a given cement ratio (20%–50%) and density (900–1400 kg/m3) was found to be approximately 100–1000 times of that of (cement stabilized) clays without foaming, whereas the strength decreased only by 2–4 times. Microstructure investigation indicated that the Hydraulic Conductivity of foamed cement-stabilized marine clays was mainly dominated by the macro pore volume (>1 μm). Furthermore, a greater cement ratio and more active metakaolin additives enable developing an innovative material for columns that satisfy both the strength and Hydraulic Conductivity requirement.
Xiaopei Zheng - One of the best experts on this subject based on the ideXlab platform.
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Hydraulic Conductivity and strength of foamed cement-stabilized marine clay
Construction and Building Materials, 2019Co-Authors: Yongfeng Deng, Yu-jun Cui, Xiaopei Zheng, Zhenping Zhao, Yonggui Chen, Fusheng ZhaAbstract:In traditional soft ground improvement of cement stabilized columns, strength was paid more attention than Hydraulic Conductivity, but the latter can improve the settlement uniformity and long term safety. This study introduced the pore-making technology referring the foaming concrete/mortar in an attempt to improve the Hydraulic Conductivity of the stabilized marine clays. The flexible wall permeameter and unconfined compressive strength (UCS) tests were conducted to depict the macro behaviour, and then the mercury intrusion porosimetry (MIP) tests and scanning electron microscopy (SEM) tests were performed to clarify the micro-structures. The Hydraulic Conductivity of foamed cement-stabilized marine clay at a given cement ratio (20%–50%) and density (900–1400 kg/m3) was found to be approximately 100–1000 times of that of (cement stabilized) clays without foaming, whereas the strength decreased only by 2–4 times. Microstructure investigation indicated that the Hydraulic Conductivity of foamed cement-stabilized marine clays was mainly dominated by the macro pore volume (>1 μm). Furthermore, a greater cement ratio and more active metakaolin additives enable developing an innovative material for columns that satisfy both the strength and Hydraulic Conductivity requirement.
