scholarly journals Shrinkage Curves for Powder and Granular Bentonites

2019 ◽  
Vol 92 ◽  
pp. 07009
Author(s):  
Martin Wijaya ◽  
Eng Choon Leong ◽  
Hossam Abuel-Naga
Keyword(s):  
Volume Change ◽  
Low Permeability ◽  
Self Healing ◽  
Geosynthetic Clay Liners ◽  
Clay Liners ◽  
Swelling Properties ◽  
Shrinkage Curve ◽  
Shrinkage Behaviour ◽  
Different Types ◽  
Surrounding Soil

Bentonite is one of the most commonly used materials in geotechnical engineering applications especially for isolation purposes due its low permeability and its highly expansive nature. For instance, Geosynthetic Clay Liners (GCL) self-healing ability relies on the swelling properties of the bentonite to close any holes in the GCL while the low permeability of the bentonite serves to reduce the infiltration of leachate to the surrounding soil. However, different types of bentonite have different shrinkage or swelling properties and hence affects the effectiveness of the GCL. A method to assess the wetting/drying induced volume change of the bentonite is through its shrinkage curve. This paper focuses on the shrinkage behaviour of reconstituted granular and powder bentonites which are used in GCL. Photogrammetry method is used to measure the volume change of specimen during drying. The shrinkage curves of the bentonites are then compared with other bentonites from the literature.

Geosynthetic Clay Liners (GCLs)

2002 ◽  
Author(s):  
Bruno Herlin ◽  
Kent von Maubeuge
Keyword(s):  
Cost Savings ◽  
Low Permeability ◽  
Compacted Clay ◽  
Geosynthetic Clay Liners ◽  
Clay Liners ◽  
Research Level ◽  
The World ◽  
Fuel Storage ◽  
Technical Properties ◽  
Nonwoven Geotextile

Geosynthetic Clay Liner’s (GCLs) are an established sealing product in the geoenvironmental industry. They are used in landfill applications as caps and base liners, secondary containment for fuel storage facilities, as well as within various other containment structures such as dams, canals, rivers, and lakes. Rolled out like a carpet to provide a durable impermeable liner, Geosynthetic Clay Liners consist of a layer of high swelling sodium bentonite sandwiched between two geotextiles. Manufactured around the world in different techniques, the Canadian manufactured GCL, is mechanically bonded by needlepunching from one nonwoven geotextile through the bentonite to the other nonwoven or woven geotextile. The low hydraulic conductivity of the GCLs are used mainly as a replacement to thick, difficult to build compacted clay liners to provide a barrier to liquids and gases, offering both a technical and economical advantage. GCLs, with an average thickness of 7mm, offer a volume advantage over Compacted Clay Liners. They are more capable of withstanding freeze-thaw and wet-dry cycles; offer substantial construction cost savings in reduced on-site QC/QA and a quicker installation. Furthermore, GCLs offer equivalent or lower rates of release of fluids and chemicals than Compacted Clay Liners (CCLs). Bentonite is a clay mineral with expansive characteristics and low permeability, where montmorillonite is the chief mineral. Montmorillonite, swells when contacted with water approximately 900% by volume or 700% by weight. When hydrated under confinement, the bentonite swells to form a low permeability clay liner, the equivalent hydraulic protection of several feet of compacted clay. A relatively new engineering material for some, geosynthetic clay liners have been used extensively over the past two decades, and are finding increasing use in every sector of the environmental industry. This paper will review the technical properties of these materials, their documentation at the research level, their integrity as a sealing barrier and recent field applications in the pipeline industry. Further, because these materials are factory produced, their properties are predictable, assisting the engineer to design with a high confidence level. Technical properties and economical benefits are sure to further increase GCL installations around the world to protect our environment and more importantly our groundwater.

Self-Healing Properties of Geosynthetic Clay Liners

2001 ◽  
Vol 8 (5) ◽  
pp. 461-470 ◽  
Author(s):  
G.L. Sivakumar Babu ◽  
H. Sporer ◽  
H. Zanzinger ◽  
E. Gartung
Keyword(s):  
Self Healing ◽  
Geosynthetic Clay Liners ◽  
Clay Liners

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

scholarly journals Insights into Desiccation and Self-Healing of Bentonite in Geosynthetic Clay Liners under Thermal Loads

2019 ◽  
Vol 92 ◽  
pp. 03006
Author(s):  
Abbas El-Zein ◽  
Bowei Yu ◽  
Ali Ghavam-Nasiri
Keyword(s):  
Hydraulic Conductivity ◽  
Mechanical Model ◽  
Thermal Gradients ◽  
Self Healing ◽  
Transient Phase ◽  
Geosynthetic Clay Liners ◽  
Clay Liners ◽  
Sodium Bentonite ◽  
Mechanical Loads ◽  
Numerical Investigations

Geosynthetic Clay Liners (GCLs) are widely used for protecting groundwater from pollution sources at the surface, including applications in which they are subject to significant thermal gradients. Hence, sodium bentonite in the GCL may undergo significant dehydration and cracking, and the GCL might fail as a result. The paper presents outcomes of a set of recent experimental and numerical investigations exploring the propensity of bentonite to desiccate and self-heal, as well as means of mitigating the effect of thermal gradients on the hydraulic conductivity of GCLs. An elasto-plastic thermo-hydro-mechanical model was found to yield reasonable predictions of experimental behaviour, except for the transient phase of pre-heating hydration. Introducing an airgap between the GCL and the heat source can reduce the extent of desiccation and its effects on hydraulic conductivity. However, the effectiveness of the solution will depend on other factors including subgrade, magnitude of thermal and mechanical loads and type of GCL.

Imine Based Self-Healing Hydrogel Triggered by Periodate

2020 ◽  
Author(s):  
Alexis Wolfel ◽  
Cecilia Inés Alvarez Igarzabal ◽  
Marcelo Ricardo Romero
Keyword(s):  
Functional Groups ◽  
Time Window ◽  
Crosslinking Reaction ◽  
Self Healing ◽  
Swelling Properties ◽  
Covalent Bonds ◽  
Smart Systems ◽  
Primary Amino ◽  
Vicinal Diols ◽  
Aldehyde Groups

<p>Design of materials with novel sensitivities and smart behaviour is important for the development of smart systems with automated responsiveness. We have recently reported the synthesis of hydrogels, cross-linked by <i>N,N'</i>-diallyltartardiamide (DAT). The covalent DAT-crosslinking points have vicinal diols which can be easily cleaved with periodate, generating valuable a-oxo-aldehyde functional groups, useful for further chemical modification. Based on those findings, we envisioned that a self-healable hydrogel could be obtained by incorporation of primary amino functional groups, from <a>2-aminoethyl methacrylate </a>hydrochloride (AEMA), coexisting with DAT into the same network. The a-oxo-aldehyde groups generated after the reaction with periodate would arise in the immediate environment of amine groups to form imine cross-links. For this purpose, DAT-crosslinked hydrogels were synthesized and carefully characterized. The cleavage of DAT-crosslinks with periodate promoted changes in the mechanical and swelling properties of the materials. As expected, a self-healing behavior was observed, based on the spontaneous formation of imine covalent bonds. In addition, we surprisingly found a combination of fast vicinal diols cleavage and a low speed self-crosslinking reaction by imine formation. Consequently, it was found a time-window in which a periodate-treated polymer was obtained in a transient liquid state, which can be exploited to choose the final shape of the material, before automated gelling. The singular properties attained on these hydrogels could be useful for developing sensors, actuators, among other smart systems.</p>

scholarly journals Kaolin based protective barrier in municipal landfills against adverse chemo-mechanical loadings

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Partha Das ◽  
Tadikonda Venkata Bharat
Keyword(s):  
Ionic Strength ◽  
High Ionic Strength ◽  
The Self ◽  
Design Parameters ◽  
Layered System ◽  
Geosynthetic Clay Liners ◽  
Clay Liners ◽  
Landfill Liner ◽  
First Time ◽  
Applied Stresses

AbstractIn this work, we assess the self-sealing and swelling ability of the compacted granular bentonite (GB) under an inorganic salt environment and induced overburden stresses from the landfill waste. The laboratory permeation tests with high ionic strength salt solutions reveal that the GB fails to seal and exhibits a significant mechanical collapse under different applied stresses. The applicability of GB in the form of geosynthetic clay liners as the bottom liner facilities in landfills that produce high ionic strength salt leachates, therefore, remains a serious concern. We propose an additional barrier system based on kaolin, for the first time, to address this problem. The proposed kaolin-GB layered system performs satisfactorily in terms of its sealing and swelling ability even in adverse saline conditions and low overburden stresses. The kaolin improves the osmotic efficiency of the self and also helps the underlying GB layer to seal the inter-granular voids. The estimated design parameters by through-diffusion test suggest that the kaolin-GB layered system effectively attenuates the permeant flux and suitable as a landfill liner.

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