Geotechnical characterization and performance assessment of bentonite/sand mixtures for underground waste repository sealing

Akgün, Haluk

doi:10.1016/j.clay.2009.08.020

Cited by 27 publications

(10 citation statements)

References 22 publications

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“…In general, bentonite addition to sand and silt causes an increase in optimum moisture content and a reduction in maximum dry density of the mix. A similar trend was observed in the results in the literature available [1,11]. The plasticity characteristics and compaction test results are presented in Table 3.…”

Section: Compaction Testsupporting

confidence: 87%

Hydraulic conductivity and compressibility characteristics of bentonite enriched soils as a barrier material for landfills

Sobti

Singh

2017

Innov. Infrastruct. Solut.

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An experimental program was undertaken for the index and engineering properties (compaction, hydraulic conductivity and consolidation) of various mix proportions of sand, silt and coal ash with bentonite as an admixture to act as a barrier material for landfills. Thirtyfour mixes were tested in all with different categories of mixes comprising of bentonite-sand, bentonite-sand-coal ash, bentonite-coal ash, bentonite-silt and bentonite-siltcoal ash mixes with bentonite content varying from 0 to 40% and coal ash from 0 to 90%. A series of hydraulic and mechanical tests were conducted to assess the Atterberg's limits, hydraulic conductivity, compressibility characteristics, etc. of the mixes. The influence of bentonite and coal ash content, effective consolidation pressure and void ratio on the hydraulic conductivity and consolidation indices (compression index, swell index, coefficient of consolidation) was studied. The hydraulic conductivities of the sandbentonite mixtures decreased from 1.75 9 10 -5 to 3.34 9 10 -11 m/s, when the bentonite content increased from 0 to 40%. An optimum amount of admixture viz. bentonite to be added to the base materials i.e. sand, silt and coal ash to obtain different category of mixes was ascertained. Disregarding the 5% soil-bentonite mix in case of sand and coal ash, an optimum mix of 10% sand-bentonite, 10% coal ash bentonite and a range of 5-10% for silt-bentonite is recommended for use as a barrier material considering the present study. The addition of coal ash to bentonite had a favourable effect on the properties of the mix in terms of hydraulic conductivity, to act as a barrier material.

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Section: Compaction Testsupporting

confidence: 87%

Hydraulic conductivity and compressibility characteristics of bentonite enriched soils as a barrier material for landfills

Sobti

Singh

2017

Innov. Infrastruct. Solut.

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“…The hydraulic conductivity of PAB and SB mixes compacted to their respective MDD at OMC are determined. The hydraulic conductivity of bentonite-based liner materials reported by Akgun et al (2006), Akgun (2010), Oren et al (2011) and Sobti and Singh (2017) is presented in Figure 6(a) along with the results of the present investigation. At low bentonite content, a sharp reduction in hydraulic conductivity of compacted PAB and SB mixes is observed with an increase of bentonite content.…”

Section: Resultssupporting

confidence: 68%

Characterization of pond ash-bentonite mixes as landfill liner material

Rout

Singh

2020

Waste Manag Res

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Characterization of pond ash-bentonite mixes is made to assess their suitability as liner material for waste disposal facilities by examining the relevant index and engineering properties. Further, a comparative assessment is made between sand-bentonite and pond ash-bentonite mixes for the range of bentonite content varying from 0 to 30% by weight at an interval of 5% to ensure an effective substitution of sand with pond ash. Addition of bentonite to sand or pond ash significantly influences the plasticity, strength and permeability properties. Besides, the shape parameters of the coarser fraction and morphology of compacted mixes also influence the engineering properties. A multiple linear regression equation is suggested to predict the hydraulic conductivity of these mixes by considering the basic material properties such as liquid limit, plasticity index and void ratio as an input variable with a correlation coefficient of 0.92 between the measured and predicted hydraulic conductivity values. At comparable conditions, compacted pond ash-bentonite mixes exhibit higher strength but also higher permeability than sand-bentonite mixes. Pond ash-bentonite and sand-bentonite mixes met the liner requirements when compacted with modified Proctor compaction effort at a minimum bentonite content of 20% and 15%, respectively.

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“…The study of Kenney et al [9] investigated the hydraulic conductivity of compacted bentonite-sand mixtures. Other works included research studies of the effect of the amount of fine soils (clay or bentonite) on the hydraulic conductivity of sand-clay and sand-bentonite mixtures [10][11][12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

“…It is evident that no one type of cell is best suited to all applications. Many researchers used conventional techniques to determine the hydraulic conductivity of the sand-clay mixtures [14,15,18,20,21]. Tavenas et al and Dafalla et al [22,23] used the consolidation tests as an indirect approach to measure the hydraulic conductivity of sand-clay mixtures.…”

Section: Introductionmentioning

confidence: 99%

Predicting Hydraulic Conductivity for Flexible Wall Conditions Using Rigid Wall Permeameter

Shaker

Dafalla

Al-Mahbashi

et al. 2022

Water

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The hydraulic conductivity is known as the soil properties that mostly vary over an order of magnitude. There are many laboratory test methods to determine the hydraulic conductivity of the soil. Each test has its own merits, drawbacks and limitations. One of these methods is the measurement using a rigid wall permeameter (RWP), which is a common practice to obtain the fluid transmissibility characteristics of the soil matrix. This type of permeameter has the advantages of low cost, simplicity of test equipment, and adaptability to many different types of permeant liquids. Another method is the measurement through a flexible wall permeameter (FWP). The hydraulic conductivity measured using the FWP is conducted in a confined cylinder in which water flow is forced into one direction. The main disadvantage of this type is being relatively more expensive and needs more time to perform the test compared to the RWP. This study is aimed at comparing three testing conditions to obtain an adjustment factor for the hydraulic conductivity test normally carried out in practice in order to cut down the time needed to perform the test as well as its cost. Different mixtures of sand and expansive clay addition were considered to examine the effect of expansive clay content on the values of the hydraulic conductivity. Tests results revealed that the clay content had a significant effect on the swelling potential, which was attributed to structural changes in the mixtures. The hydraulic conductivity of mixtures decreases with the increase in clay content. The hydraulic conductivity of mixtures tested using FWP was observed to be lower than that of mixtures tested using RWP at similar clay contents. The tests conducted enabled establishing a correction factor to adjust the hydraulic conductivity normally obtained in practice using rigid wall cells.

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Geotechnical characterization and performance assessment of bentonite/sand mixtures for underground waste repository sealing

Cited by 27 publications

References 22 publications

Hydraulic conductivity and compressibility characteristics of bentonite enriched soils as a barrier material for landfills

Hydraulic conductivity and compressibility characteristics of bentonite enriched soils as a barrier material for landfills

Characterization of pond ash-bentonite mixes as landfill liner material

Predicting Hydraulic Conductivity for Flexible Wall Conditions Using Rigid Wall Permeameter

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