Comparative Study on Performances of Clay -Bentonite and Bentonite -Quarry Dust Mixture as Landfill Liner (original) (raw)
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Compacted sandy soils with addition of bentonite have been used in a variety of geotechnical structures as engineered barriers, such as in landfill liners and hydraulic containment structures. In this study, Igbokoda sand was mixed with bentonite at varying percentages of 0%, 2%, 4%, 6%, 8% and 10% by weight of sand. Strength tests, which include compaction test, California Bearing Ratio (CBR) test and direct shear test, were performed on various sand-bentonite mixtures using standard methods. Hydraulic conductivity tests were also performed on various sand-bentonite mixtures in order to determine their suitability as landfill liner. Results from the tests showed that 8% of bentonite with sand mixture had a hydraulic conductivity below 1×10-7 cm/s, a cohesion value of 250 kN/m 3 and a reasonable strength (CBR) value of 54.07% using the West Africa standard compactive method, hence being the safest of the selected varying percentages for the design of a landfill liner.
Laboratory Studies on Unconfined Compressive Strength of Solid Waste Landfill Liner Material
Compacted natural clay soils are used as liners and covers in waste containment facilities. Liners are generally made of compacted natural inorganic clays or clay soils. The liner is one of the most important elements on a waste disposal landfill. Clay soils are used for constructing landfill liners because they have low hydraulic conductivity and can attenuate organic and inorganic contaminants. In the absence of impermeable natural soils, compacted mixtures of bentonite and soil are used to form barriers to fluid transmission. The shear strength and unconfined compressive strength may have influence over the hydraulic barrier which is the indicator of the performance of the liner. Laboratory tests are conducted on clay soil samples mixed with microsilica in different proportions to demonstrate to demonstrate the increase in the strength of compacted clay soil liners and covers. The strength behavior observed in this study of clay is used to evaluate the performance of clay soil with and without mircosilica admixture addition.
Environmental and Sustainability Indicators, 2023
Liners are provided under engineering landfill sites to block the downflow of leachates and their noxious components to minimize pollution in the underlying aquifers or neighboring water bodies. Compacted clays are widely employed as suitable materials for constructing landfill liners because of their low hydraulic conductivity, balanced swelling potentials, and appropriate compressive strength. However, the quality has to be improved if the locally available soil does not meet the minimum standards for constructing liner materials. Including bentonite dosage with local soil can show better stability and strengthened cohesion bonds between molecules. This paper aims at a recent study on specific geotechnical properties of bentonite amended local Khulna clay soil intended to be used as a liner material. Bentonite in varying proportions (e.g., 5%, 10%, 15%, and 20%) was mixed with local soil, and specific tests (e.g., compaction tests, consistency tests, hydraulic conductivity tests, free swell tests, unconfined compressive strength tests, and pH tests) were conducted on the mixtures. Results indicated that the optimum moisture content (14.03%-19.30%), liquid (35.39%-53.98%), plastic (22.20%-35.23%), plasticity index (13.19%-18.75%), pH (7.23-7.43), swell index (3.13%-24.2%) and unconfined compressive strength (156.21 kPa-244.46 kPa) increased while bentonite was in conjuncture with the soil. In contrast, maximum dry density (17.80 kN/m 3 to 16.80 kN/m 3) and hydraulic conductivity (2.39 × 10 − 7 cm/s to 0.09 × 10 − 7 cm/s) decreased. Also, at 10% bentonite content, the mixture matched the acceptable standards for liner construction (hydraulic conductivity 0.29 × 10 − 7 cm/s <10 − 7 cm/s, and unconfined compressive strength = 210 kPa > 200 kPa).The study identified that adding bentonite to local soil can improve its geotechnical properties, making it a suitable material for landfill liners with increased strength and decreased hydraulic conductivity.
Geotechnical Evaluation of Bentonite Clay for Municipal Solid Waste Landfill Lining Membrane
2018
Evaluation method for 1 kg each of the three clay samples collected from Okada, Okpila and Oduna in Edo state, Nigeria, included elemental composition, and geotechnical methods such as attergerg limit test, grain size analysis and consolidated test method according to British Standard (BS) Code 1377. Considering ASTM standard requirement for landfill compacted clay liner, the sample collected from Oduna met the requirement with hydraulic conductivity of 1.077x10-7, liquid limit of 50.2%, plasticity index of 31% and 54.8% grain particles passing through #200 sieve size. The accuracy of the geotechnical evaluation was confirmed by using 50.2% liquid limit of 1 kg Oduna clay as 1 m thickness in the prototype landfill base and side walls, of which no shrinkage and desiccation cracking occurred upon drying. This is possibly due to the substantial percentage of Al2O3 (73.35%), SiO2 (18.80) and MgO (4.51%) in the clay crystal structure which primarily constitutes smectite.
2014
This thesis presents the findings of laboratory work on behavior of landfill liner using crushed siltstone and kaolinite. The selection of landfill liner are based on compatibility with the soil environment, resistance of load from waste, and also groundwater levels. Inspired by using waste material as engineering purpose, therefore this study is to determine the physical properties of composite kaolinite clay-crushed siltstone liner, to predict the effect of composite on hydraulic conductivity and engineering characteristic of composite kaolinite clay-crushed siltstone liner and also to analyze the settlement result by using Plaxis Modelling.There is a paucity of the previous research, where the study on the liner material is lacking. Therefore, in the present study, an alternative liner made of composite material is studied and developed. The waste material that had been used in this studied was crushed siltstone which then sandwiched with kaolinite layers and vice versa. The crus...
Compacted sand–bentonite mixtures for the confinement of waste landfills
Acta geotechnica, 2024
This paper illustrates the results of an experimental study on sand-bentonite mixtures for their use as confinement barriers for solid waste landfills. The mixtures have been prepared parametrically varying the percentage of bentonite. The sample preparation method was established willing to simulate the compaction processes on site. In fact, the compacted samples were tested following two different stress-wetting paths representative of the possible stress and imbibition sequences occurring on a landfill confinement barrier. In the first case, the barrier comes into contact with rainwater before being subjected to the overloading stress induced by waste disposal, while, in the second case, the barrier is overloaded by the waste before being wetted by the leachate. The compressibility and permeability of the sand-bentonite mixtures were determined, in both cases, by oedometric compression tests. The experimental results are analysed and compared in order to evaluate the influence of the bentonite content on the mechanical and hydraulic behaviour of the mixture. Interpretation of the results is also accomplished with a micro-mechanical investigation of the mixtures fabric. Suitable compositions of sand and bentonite are finally proposed for the design of effective confinement barriers. Keywords Bentonite compaction Á Bentonite swelling Á Bentonite hydraulic conductivity Á Compaction of sand-bentonite mixtures Á Hydraulic conductivity of sand-bentonite mixtures Á Oedometer test on bentonite Á Oedometer test on sandbentonite mixtures Á Sand-bentonite mixtures Á Swelling of sand-bentonite mixtures Á Waste landfills confinement & Erminio Salvatore
Compacted Kerman Clay Liner: Different Permeants and Different Additives
Journal of Engineering in industrial research, 2021
This study investigated the feasibility of using Kerman collapsible clay excavated in an urban project as landfill liner material. Several technical requirements must be addressed for a material to be used as liners among which low hydraulic conductivity and high compressive strength are the most important. To achieve this goal, a set of laboratory tests were conducted on the prepared samples. Sample preparation was done and the soil was tested in pure form as well as in lime, bentonite and Nanoscale treated forms. Two different methods were used to determine the permeability of the specimens, falling head (with a direct method), and consolidation (with an indirect method). The results indicated that overall, the hydraulic conductivity obtained from the consolidation test was lower than those of falling head tests. The falling head method was conducted for all specimens using municipal and synthetic leachate instead of water. Samples with 0.4% Nano silica and 8% lime under municipal waste leachate met the EPA permeability requirements. The same procedure was carried out under the synthetic leachate. The results showed that only the specimen with 0.4% Nano silica met the EPA regulation standard. The unconfined compression strength values exhibited a considerable increase in addition of lime and Nano silica and a gradual decrease with adding bentonite. This study showed that Kerman clay can be used as a liner material when supplemented with lime and Nano silica.
The Potential of Marine Clay Used for Landfill Liner: A Geotechnical Study
International Journal of GEOMATE
The increase in excessive solid waste due to the rapid growth of the world's population is considered a severe environmental problem. The landfill leachate will contaminate groundwater, putting all living things at risk. Natural clay is a common liner material used to keep landfill leachate from polluting the environment. This study investigates the geotechnical properties of natural marine clay and its potential to be used as a landfill liner. To investigate the soil properties, the Sungai Besar marine clay (SBMC) was subjected to physico-chemical, morphology and mineralogy properties including particle size distribution, specific gravity, atterberg limits, compaction, permeability, pH, organic content, cation exchange capacity (CEC), specific surface area (SSA), X-Ray Diffraction (XRD) and scanning electron microscope (SEM). Batch Equilibrium Test was conducted to determine the effectiveness of SBMC in adsorbing heavy metals (Pb 2+ , Cu 2+ , Co 2+ , Cd 2+ , Ni 2+ , Zn 2+). Results showed SBMC has a high percentage of fine grain size (silt 73-87% +clay 12-19 %), lower value of specific gravity (2.14-2.29), high liquid limit (79.50-84.00%), plasticity limit (49.18-59.35 %), plasticity index (20.15-34.22 %) and was categorized at very high plasticity in plasticity indexed chart. The SBMC also has maximum dry density value (1.36-1.37 g/cm 3), optimum moisture content, wopt (34.55-37.97 %) and average hydraulic conductivity (6.35 x 10-7-6.88 x 10-7 m/s). The chemical properties of the SBMC1 showed it has a high pH value (6.95-7.42), organic matter (5.31-6.06 %), CEC (91.25-92.32 meq/100g), and SSA value (60.28-62.38 m 2 /g). The XRD results showed that kaolinite, and illite were the most prevalent clay minerals, with quartz as the non-clay mineral. SEM analysis also revealed that kaolinite and microfossils were within the SBMC. The Batch Equilibrium test also showed that SBMC in single solution exhibited higher sorption for Cu (Kd= 0.4499 L/g, R 2 =0.98), followed by Pb (Kd= 0.3701 L/g, R 2 =0.85), Co (Kd= 0.3232 L/g, R 2 = 0. 0.88), Ni (Kd= 0.1483 L/g, R 2 =0.98), Zn (Kd= 0.0711 L/g, R 2 = 0.93) and Cd (Kd= 0.0627 L/g, R 2 = 0.98). Based on physico-chemical, mineralogy and morphology results, SBMC is an excellent choice acting as natural clay-based energy material to be used as an engineered clay liner in a landfill area.
International Agrophysics, 2015
A b s t r a c t. This paper presents studies concerning the applicability of two clay materials for the construction of a sustainable landfill liner. The studies consisted in determination of basic characteristics of the materials, eg particle size distribution, bulk density, particle density, total porosity, pore size, mineralogy, specific surface area, nanoparticle size, and Atterberg limits, as well as measurements of their geotechnical and hydraulic parameters, such as in situ saturated hydraulic conductivity, modules of primary and secondary compression, cohesion, and angle of internal friction. Furthermore, the effects of compaction performed by the Proctor method at various water contents on swelling and shrinkage characteristics and saturated hydraulic conductivity were investigated in order to determine the compliance with the national requirements for selection of material for landfill liner construction. The determined characteristics and geotechnical parameters of the tested clay materials allowed qualifying them as suitable for municipal landfill construction. The shrinkage potential of the tested clays observed was rated as moderate to very high. The cyclic drying and rewetting of the clay materials performed resulted in a significant increase in saturated hydraulic conductivity. Thus, the clay sealing layers, as part of a multilayer liner, should be very carefully operated, preventing the drying out of the clay sealing and assuring the possibility of its constant saturation.
Assessment of municipal solid waste clay liner system using consolidation test
The present study has been carried out to provide landfill clay liner soil with admixture microsilica in different proportions. The geoenvironmental and physico-chemical characteristics were carried out to characterize the clay mixed with definite portion of microsilica in mass ratio. An experimental investigation was performed to determine the effect of clay and microsilica consolidation of leachate. The microsilica-clay composites were mixed in ratios of 0:100, 1:10 and 1:20 and experiment carried out with leachate as the permeation liquid. The quantitative reductions in coefficient of permeability increase in the effective stress for the all ratios. The chemical reaction of water and soil are lower than that in the leachate. In real field the leachate as permeation liquid after construction of liners, is retained by adding microsilica in clay liner system. 1:10 ratio of microsilica-clay composites was found to be more suitable municipal solid waste leachate as permeating liquid.