Towards a more rational approach to chemical compatibility testing of clay

2002 ◽  
Vol 39 (3) ◽  
pp. 597-607 ◽  
Author(s):  
J K Kodikara ◽  
F Rahman ◽  
S L Barbour
Keyword(s):  
Boundary Condition ◽  
Hydraulic Conductivity ◽  
Rigid Wall ◽  
New Technique ◽  
Rational Approach ◽  
Lateral Strain ◽  
Test Results ◽  
Chemical Compatibility ◽  
Test Technique ◽  
Flexible Wall

Chemical compatibility tests using hydraulic conductivity testing with chemical permeants are normally undertaken to assess the integrity of compacted clayey liners used for waste containment. This paper highlights the fact that current routine methods of flexible wall and rigid wall testing techniques fail to represent the zero lateral strain boundary condition that is required to realistically represent the field situation. The test results indicate that flexible wall permeameters underestimate the likely increases in hydraulic conductivity due to chemicals, while the rigid wall permeameters can severely overestimate these effects. A new test technique, which incorporates the zero lateral strain condition in a simple manner, is presented. This technique involves the use of a rigid wall concept in a flexible wall permeameter. A split rigid mould is used to encase the soil specimen that is glued to the internal surfaces of the mould, to apply the zero lateral strain boundary condition. The new technique is shown to be suitable for both chemical compatibility and desiccation testing. The tests were undertaken with varying concentrations of saline water, methanol, and landfill leachate. The test results indicate that the new technique produces results that fall between the results obtained from flexible wall and rigid wall permeameters. It is argued that the new test technique provides a more rational approach for chemical compatibility testing than the current rigid wall and flexible wall techniques.Key words: soil, hydraulic conductivity, chemical compatibility, landfill, permeameter, boundary condition.

scholarly journals Laboratory investigation of self-healing properties on geosynthetic clay liners with flaw

2015 ◽  
Vol 41 (1) ◽  
pp. 53-58 ◽  
Author(s):  
Guang-Wei Zhang ◽  
Hu-Yuan Zhang ◽  
Jin-Fang Wang ◽  
Lang Zhou ◽  
Ping Liu ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
The Self ◽  
Distilled Water ◽  
Self Healing ◽  
Test Results ◽  
Geosynthetic Clay Liners ◽  
Clay Liners ◽  
Order Of Magnitude ◽  
Flexible Wall ◽  
Research Findings

Abstract The objective of this paper is to evaluate the self- healing properties of a commercially-available geosynthetic clay liner (GCL) using flexible-wall permeameter. The GCLs are produced by the same factory, but the contents of bentonite are different. Also the hydraulic conductivities (HC) of GCLs with no defect are different. In this study, specimens were completely saturated under the backpressure of 20 kPa before the test. Permeability tests were performed on GCL specimens with penetrating flaw and also on specimens permeated with distilled water and CaCl2 solutions. The test results were presented and discussed. Experimental results showed that the GCL with penetrating flaw did not exhibit complete self-healing in the case of flaw. After 120 days, the hydraulic conductivity increased by approximately an order of magnitude. In addition, CaCl2 solutions had a significant influence on the hydraulic conductivity. The research findings might be of interest to researchers and engineers who design liners for landfills and other liquid containment facilities

Study on the Hydraulic Conductivity of Sand-Bentonite mixtures used as Liner System of Waste Landfill

2011 ◽  
Vol 194-196 ◽  
pp. 909-912 ◽  
Author(s):  
Si Fa Xu ◽  
Zhe Wang ◽  
Yong Zhang
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Layer ◽  
Low Permeability ◽  
Test Results ◽  
Natural Clay ◽  
Compacted Soil ◽  
Waste Landfill ◽  
Liner System ◽  
Flexible Wall ◽  
Soil Liner

A liner system such as liner sheet underlying impermeable soil layer having hydraulic conductivity less than 1*10-7 cm/s and a thickness larger than 100 cm is often used in china. As there is very little natural clay having such low permeability, bentonite is usually mixed into sand to decrease the permeability. In this paper, the compaction tests and permeability testing using flexible-wall permeameter are conducted. The test results show that the value of critical benonite ratio depends on bentonite ratio, and the hydraulic conductivity of the sand mixed with critical bentonite ratio for distilled water shows of the order of 1*10-8 cm/s that satisfies the china standard requested as compacted soil liner of waste landfill. Finally, the permeability testing used leachate including calcium component was conducted.

scholarly journals Effect of Confining Conditions on the Hydraulic Conductivity Behavior of Fiber-Reinforced Lime Blended Semiarid Soil

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3120
Author(s):  
Abdullah Ali Shaker ◽  
Mosleh Ali Al-Shamrani ◽  
Arif Ali Baig Moghal ◽  
Kopparthi Venkata Vydehi
Keyword(s):  
Hydraulic Conductivity ◽  
Expansive Soils ◽  
Dry Weight ◽  
Rigid Wall ◽  
Saturated Hydraulic Conductivity ◽  
Morphological Properties ◽  
Expansive Clay ◽  
Confining Pressures ◽  
Flexible Wall ◽  
Fiber Materials

The hydraulic properties of expansive soils are affected due to the formation of visible cracks in the dry state. Chemical stabilization coupled with fiber reinforcement is often considered an effective strategy to improve the geotechnical performance of such soils. In this study, hydraulic conductivity tests have been conducted on expansive clay using two different types of fibers (fiber cast (FC) and fiber mesh (FM)) exhibiting different surface morphological properties. The fiber parameters include their dosage (added at 0.2% to 0.6% by dry weight of soil) and length (6 and 12 mm). Commercially available lime is added to ensure proper bonding between clay particles and fiber materials, and its dosage was fixed at 6% (by dry weight of the soil). Saturated hydraulic conductivity tests were conducted relying on a flexible wall permeameter on lime-treated fiber-blended soil specimens cured for 7 and 28 days. The confining pressures were varied from 50 to 400 kPa, and the saturated hydraulic conductivity values (ksat) were determined. For FC fibers, an increase in fiber dosage caused ksat values to increase by 9.5% and 94.3% for the 6 and 12 mm lengths, respectively, at all confining pressures and curing periods. For FM fibers, ksat values for samples mixed with 6 mm fiber increased by 12 and 99.2% for 6 and 12 mm lengths, respectively for all confining pressures at the end of the 28-day curing period. The results obtained from a flexible wall permeameter (FWP) were compared with those of a rigid wall permeameter (RWP) available in the literature, and the fundamental mechanism responsible for such variations is explained.

Granular soils in rigid-wall permeameters: method for determining the degree of saturation

1989 ◽  
Vol 26 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Robert P. Chapuis ◽  
Karsten Baass ◽  
Luc Davenne
Keyword(s):  
Hydraulic Conductivity ◽  
Test Procedure ◽  
Rigid Wall ◽  
Standard Test ◽  
Test Method ◽  
Degree Of Saturation ◽  
Granular Soils ◽  
Test Results ◽  
Constant Head

The standard test method used to determine the hydraulic conductivity of a clean granular soil (rigid-wall permeameter –constant head difference) requires that the specimen be saturated with an air-vacuum pump. However, no method is provided to verify whether the sample is fully (100%) saturated. This paper proposes such a method and establishes its accuracy. The method allows for quality control of the rigid-wall permeameter itself: it can detect if it is watertight but not airtight, according to the achieved degree of saturation. A detailed example is given on a proposed data sheet. The reasons for partial saturation and the problems related to air bubbles are examined. The result of this examination is a simplified test to check a permeameter, based on the fact that for unsaturated conditions the hydraulic conductivity depends on which of two ways the water seeps in a given direction. A few modifications in the preparation of the specimen and the test procedure are suggested so as to improve the quality of test results. Key words: permeability, laboratory, granular soils, rigid-wall permeameter, saturation.

Comparison between Charpy Transition Temperature TCVN and Reference Temperature T° for 10Ni3CrMoV Steel

2007 ◽  
Vol 539-543 ◽  
pp. 4488-4493
Author(s):  
Yi Fei Gao ◽  
Jun Chang Shen ◽  
Bo Qun Wu
Keyword(s):  
Heat Treatment ◽  
Transition Temperature ◽  
Material Design ◽  
Reference Temperature ◽  
Test Results ◽  
Test Technique ◽  
Fracture Appearance Transition Temperature ◽  
Qt Steels ◽  
Fracture Appearance ◽  
Lower Tolerance

Charpy transition temperature TCVN and reference temperature To for 10Ni3CrMoV steel were determined using two different experimental techniques such as Charpy V-notch impact test technique and reference temperature To test technique. It was found that two methods provided different test results. The median master curve with upper and lower tolerance bounds was got from the test. The upper tolerance bound is often used for material design and application. At the same time the TCVN and To results were discussed for two kinds of heat treatment which are QT(Quenching and Temper) and QLT(Quenching, anneal and temper). JC (med ) K values calculated were 101 and 105MPam1/2 for the QT and QLT steels, respectively. These indicated that the QLT steels have the higher JC (med ) K , the lower reference temperature and lower energy (or fracture appearance) transition temperature(ETT50 or FATT50) than the QT steels. This was mainly related with the different microstructures of two kinds of heat treatment.

Research on Hydraulic Conductivity of Coarse Sandstone under Triaxial Compression

2011 ◽  
Vol 94-96 ◽  
pp. 1146-1151 ◽  
Author(s):  
Guan Rong ◽  
Xiao Jiang Wang
Keyword(s):  
Hydraulic Conductivity ◽  
Circumferential Strain ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Test Results ◽  
Stress Strain ◽  
Deformation And Failure ◽  
Maximum Value ◽  
Strain Process ◽  
Peak Value

Permeability test for complete stress-strain process of coarse sandstone were carried out in triaxial test instrument. On the basis of test results, the influence of confining pressure and strain on the hydraulic conductivity was discussed. It is shown that in the complete stress-strain process, hydraulic conductivity changes in the law that presents the same character with the curve of stress-strain. The hydraulic conductivity reduces slightly with the increase of deviatoric stress in the stage of micro fracture compressing and elastic; In the elastoplastic stage, along with the expansion of new fractures, the hydraulic conductivity increases slowly at first and then reaches sharply to the maximum value after peak point; In the post-peak stage, the fracture which controls the hydraulic conductivity of coarse sandstone is compressed because of the confining pressure and the hydraulic conductivity decreases. During the process of deformation and failure, the hydraulic conductivity is more sensitive to the change of circumferential strain. With the increase of confining pressure, the increased value from initial to peak value and the decreased value from peak to residual value decreases.

scholarly journals PENINGKATAN KEMAMPUAN MENULIS PARAGRAF DESKRIPTIF SISWA KELAS X SMA NEGERI 02 BENGKULU TENGAH DENGAN MENGGUNAKAN METODE MENULIS BERANTAI (ESTAFET WRITING)

2016 ◽  
Vol 2 (2) ◽  
pp. 157-163
Author(s):  
Heni Puspita
Keyword(s):  
Data Analysis ◽  
Research Data ◽  
Test Results ◽  
Test Cycle ◽  
Test Technique ◽  
Qualitative And Quantitative ◽  
Average Value ◽  
School Year ◽  
Analysis Technique ◽  
Photo Documentation

The purpose of this study for improve the students class X1 skill of SMAN 2 Central Bengkulu Tengah in write descriptive paragraph with estafet writing method. This study design is the design of classroom action research conducted in two cycles, the first cycle and the second cycle. Collecting data on the first cycle and the second cycle using test technique and nontest. The test used is a test action in the form of assignment to write a description, whereas nontest techniques used in the form of guidelines for observation, the journal guidelines, interview guides, and photo documentation guidelines. Data analysis technique of this research is qualitative and quantitative. Quantitative techniques are used to analyze and compare test results pre-cycle, the first cycle, the second cycle, and qualitative techniques used to analyze and compare the results nontest in the first cycle and the second cycle. Based on the analysis of research data, in class X1 totaling 30 students can be concluded that by using the estafet writing method can increase the skill of writing a paragraph descriptive. In the first cycle, the value of an average of 71.65% in the second cycle, the average value of 88.73%, an increase of 17.08%. This means that there is an increase in the skill of writing a paragraph descriptive of the students with estafet writing method. This increase can be seen from the results of tests conducted students in class X SMAN 2 Central Bengkulu 2016/2017 school year that includes the end of the test cycle test cycle I and II.  

Characteristics of groundwater seepage with cut-off wall in gravel aquifer. I: Field observations

2015 ◽  
Vol 52 (10) ◽  
pp. 1526-1538 ◽  
Author(s):  
Yong-Xia Wu ◽  
Shui-Long Shen ◽  
Ye-Shuang Xu ◽  
Zhen-Yu Yin
Keyword(s):  
Hydraulic Conductivity ◽  
Clayey Soil ◽  
Retaining Wall ◽  
Ground Surface ◽  
Test Site ◽  
Second Phase ◽  
Confined Aquifer ◽  
Test Results ◽  
Sandy Gravel ◽  
High Hydraulic Conductivity

This paper presents a case history of the leakage behavior during dewatering tests in the gravel strata of an excavation pit of a metro station in Hangzhou, China. The groundwater system at the test site is composed of a phreatic aquifer underlain by an aquitard and a confined aquifer with coarse sand and gravel. The sandy gravel stratum has very high hydraulic conductivity. The maximum depth of the excavation is 24 m below the ground surface, which reaches the middle of the aquitard strata, where the thickness of the clayey soil is insufficient to maintain the safety of the base of the excavation. To understand the hydrological characteristics of gravel strata, single- and double-well pumping tests were conducted, where a cut-off wall was installed 43 m deep with its base penetrating 2 to 3 m into the aquifer. Test results show that this partial cut-off of the aquifer cannot effectively protect the base of the excavation from the upward seepage force of the groundwater during excavation. Therefore, a new cut-off wall (second phase) was constructed to a depth of 54 m to cut off the confined aquifer. A second pumping test was conducted after the construction of the second phase cut-off wall, and test results show that this full cut-off combined with dewatering can control groundwater effectively during excavation. This finding indicates that when a deep excavation is conducted in a confined aquifer with high hydraulic conductivity, determination of the depth of the retaining wall should be based on three factors: the stability of the base, the upward seepage stability, and settlement control.

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