scholarly journals Influence of bentonite type and producing method on hydraulic conductivity of sand–bentonite mixture

2020 ◽  
Vol 205 ◽  
pp. 10005
Author(s):  
Tomonori Sakita ◽  
Hideo Komine ◽  
Atsuo Yamada ◽  
Hailong Wang ◽  
Shigeru Goto
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Water Mass ◽  
Water Volume ◽  
Dry Density ◽  
Initial Water Content ◽  
Specimen Preparation ◽  
Initial Water ◽  
Compaction Energy ◽  
Low Level Radioactive Waste

Sand-bentonite mixtures with bentonite content of 10-30% had been planned to handle low-level radioactive waste in Japan, because of its low permeability. Hydraulic conductivity of sand–bentonite mixture depends on the bentonite type, bentonite content, initial water content, and other factors. Given this background, falling head permeability tests were conducted on sand–bentonite mixture by varying the compaction energy for specimen preparation, initial water content (10–20%), and bentonite content (15– 30%). For these tests, the hydraulic gradient of 25-500 was set. Consequently, the hydraulic conductivities were 10-8 – 10-13 m/s for all tested conditions. Correlation between the hydraulic conductivity and the effective montmorillonite dry density (montmorillonite mass divided by the sum of montmorillonite, air, water volume), which is often used to correlate the hydraulic conductivity of bentonite, was found. Correlation was also found between the hydraulic conductivity and a new index designated as the effective montmorillonite wet density (sum of montmorillonite and water mass / sum of montmorillonite, air, water volume). Effective montmorillonite wet density reveals differences in the specimen structural distribution through consideration of the initial water content.

Experimental study on swelling characteristics of compacted bentonite

1994 ◽  
Vol 31 (4) ◽  
pp. 478-490 ◽  
Author(s):  
Hideo Komine ◽  
Nobuhide Ogata
Keyword(s):  
Water Content ◽  
Nuclear Waste ◽  
Volumetric Strain ◽  
Swelling Pressure ◽  
Dry Density ◽  
Initial Water Content ◽  
Initial Water ◽  
Compacted Bentonite ◽  
Swelling Characteristics ◽  
High Level

Compacted bentonites are attracting greater attention as back-filling (buffer) materials for repositories of high-level nuclear waste. However, since there are few studies about the swelling characteristics of compacted bentonites, it is first necessary to clarify the fundamental swelling characteristics in detail. For this purpose, various laboratory tests on the swelling deformation and swelling pressure of compacted bentonites were performed and the results analyzed. The following conclusions were drawn from the study. (i) The curve of swelling deformation versus time is strongly dependent on the initial dry density, vertical pressure, and initial water content. The maximum swelling deformation, however, is almost independent of initial water content, and the maximum swelling deformation increases in proportion to the initial dry density, (ii) The maximum swelling pressure increases exponentially with increasing initial dry density, whereas the maximum swelling pressure is almost independent of initial water content. (iii) The swelling mechanism of compacted bentonite was considered on the basis of the swelling behavior of swelling clay particles such as montmorillonite. Furthermore, a model of the swelling characteristics and a new parameter (swelling volumetric strain of montmorillonite), which were able to evaluate the swelling characteristics of compacted bentonite, were proposed. Key words : bentonite, laboratory test, nuclear waste disposal, swelling deformation, swelling pressure.

Experimental Study of Influence Factors in Unsaturated Soil Infiltration Rate

2013 ◽  
Vol 477-478 ◽  
pp. 472-475
Author(s):  
Ling Cao ◽  
Xin Zhe Li
Keyword(s):  
Water Content ◽  
Unsaturated Soil ◽  
Infiltration Rate ◽  
Water Infiltration ◽  
Dry Density ◽  
Initial Water Content ◽  
Soil Infiltration ◽  
Initial Water ◽  
Cohesive Particles ◽  
Soil Infiltration Rate

Based on the unsaturated soil ponding water infiltration test in laboratory, the influences of cohesive particles content, dry density and initial water content on infiltration rate are analyzed. Soil infiltration rate decreased with the increase of cohesive particles content and dry density; with the decrease of initial water content at low dry density, and with the increase of initial water content at high dry density.

scholarly journals STUDY ON PERMEABILITY AND ELECTRICAL RESISTIVITY OF RED CLAY CONTAMINATED BY CU2+

2021 ◽  
Vol 30 (1) ◽  
Author(s):  
Rulong Ban ◽  
Xuejun Chen ◽  
Yu Song ◽  
Pengyan Bi ◽  
Xin Yang ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Electrical Resistivity ◽  
Hydraulic Conductivity ◽  
Water Content ◽  
Contaminated Soil ◽  
Initial Water Content ◽  
Red Clay ◽  
Initial Water ◽  
Electrode Method ◽  
The Relationship

In order to study the permeability characteristics of heavy metal ions contaminated red clay and explore the rapid detection of permeability of heavy metal contaminated red clay. Through variable-head permeability test and electrical resistivity test (different voltages and methods), the effects of Cu2+ concentration and initial water content on hydraulic conductivity characteristic and resistivity of contaminated red clay was systematically investigated. The relationship between permeability characteristic and electrical resistivity was further explored by taking Cu2+ concentration and moisture content as the intermediate variable. The obtained results indicate that the different voltage has no obvious effect on the resistivity of the samples. The four-phase electrode method is more accurate than the two-phase electrode method. With increasing Cu2+ concentrations the hydraulic conductivity of specimens increases, however the permeability coefficient of contaminated soil decreases with increasing initial water content. In the resistivity test, with increasing of Cu2+ concentrations and water content, the resistivity of samples presented a downward trend, which is decreased sharply at first and then tended to be gentle. The relationship between hydraulic conductivity and resistivity of contaminated soil showed a good fitting curve no matter in different Cu2+ concentration or in different water content, but the fitting curves of them presented opposite trend.

scholarly journals Pengaruh Kadar Air Awal Dan Surcharge Pressure Pada Uji Karakteristik Pengembangan Tanah Ekspansif

2017 ◽  
Vol 23 (2) ◽  
pp. 124
Author(s):  
Wilis Diana ◽  
Edi Hartono ◽  
Anita Widianti
Keyword(s):  
Water Content ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Dry Density ◽  
Initial Water Content ◽  
Expansive Clay ◽  
Initial Water ◽  
Swelling Properties ◽  
Swell Percent ◽  
Swell Pressure

Expansive soils experience volumetric changes due to water content changes. These volumetric changes cause swell and shrink movement in soils, which in turn will inflict severe damage to structures built above them. A Proper understanding of how the expansive soil behaves during the wetting/drying process is essential for assessing the mitigation action of expansive soil hazard and design suitable foundation. The structures that build above expansive soil bed are susceptible to heave and to withstand swell pressure, thus the swell pressure must be considered in the design. This study focuses on swelling properties of two expansive clay from Ngawi, East Java and Wates, Yogyakarta. Laboratory test on disturbed samples is used to identified and to measured swelling properties. A series of swelling test was performed under constant soil dry density. The influence of initial water content and surcharge pressure on swelling properties (i.e swell percent and swell pressure) of compacted samples were investigated. The swelling properties test used ASTM standard 4546-03 method B. It was found that the lower initial water content the higher the swell percent, but the swell pressure seems not to be affected by initial water content. At the same initial water content, swell percent decrease with the increase of surcharge pressure, but swell pressure remains unchanged.

scholarly journals Factors affecting the swelling pressure for Jerash expansive soil

2021 ◽  
Vol 3 (2) ◽  
pp. 44-51
Author(s):  
Talal Masoud ◽  
Abdulrazzaq Jawish Alkherret
Keyword(s):  
Water Content ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Swelling Pressure ◽  
Dry Density ◽  
Initial Water Content ◽  
Content Increase ◽  
Initial Water ◽  
Factors Affecting ◽  
Water Content Increase

  In this study for factors effecting the swelling pressure of jerash expansive soils were investigated in this study, effect of initial dry density and effect of initial water content on the jerash expansive soil were investigated.It show that as the initial dry density decrease from 1.85 gm/cm3  to1.25 gm/cm3 , the swelling pressure also decrease are from 3.1  to 0.25gm/cm2   also it show that as the initial water content increase from 0%to 15% , the swelling pressure of jerash expansive soil decrease from 2.65 gm/cm2  to 1.35 gm/cm2  .  

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