Landfill Liner Material Research Articles

The strength and hydraulic conductivity characteristics of sewage sludge ash and natural soil mixtures – a sustainable alternate landfill liner material

ABSTRACT This paper examines the feasibility of the natural soil and sewage sludge ash (SSA) mixtures, which satisfy the criteria to be used as landfill liners. The effect of SSA content on hydraulic conductivity and strength characteristics of natural soil and SSA mixtures has been investigated through a series of laboratory tests. The results demonstrate that mixtures exhibit an increase in both hydrodynamic diffusion coefficient and strength with the increasing SSA content. With the content of SSA from 0% to 5%, the values of the hydrodynamic diffusion coefficient ( D ) ranged from 3.5 × 10−10 to 15 × 10−10 cm2/s. The increase in the hydrodynamic diffusion coefficient is minor for low SSA content and significant for SSA content exceeding 5%. The inclusion of 5% SSA content results in a hydrodynamic diffusion coefficient that is approximately three times higher than that observed in natural soil. The results were obtained from soil triaxial tests, revealing that the mixtures containing SSA exhibited a significant increase in both the initial tangent modulus and the ultimate principal stress difference compared to those of natural soil. The SSA content with the highest value exhibits maximum initial tangent modulus and ultimate principal stress. The comprehensive analysis of the strength and hydraulic diffusion conductivity of the mixtures demonstrates that the incorporation of 3% SSA results in a significant enhancement in strength, while marginally increasing hydrodynamic diffusion coefficients. Therefore, it can be inferred that the utilization of mixtures containing 3% SSA content as a liner material is suitable.

A Novel Landfill Liner Material for Solidified Lake Sediment Based on Industrial By-Product and Construction Waste: Engineering Behavior and Cr(VI) Breakdown Characteristics

Engineering sludge, industrial waste, and construction waste are marked by high production volumes, substantial accumulation, and significant pollution. The resource utilization of these solid wastes is low, and the co-disposal of multiple solid wastes remains unfeasible. This study aimed to develop an effective impermeable liner material for landfills, utilizing industrial slag (e.g., granulated blast furnace slag, desulfurized gypsum, fly ash) and construction waste to consolidate lake sediment. To assess the engineering performance of the liner material based on solidified lake sediment presented in landfill leachate, macro-engineering characteristic parameters (unconfined compressive strength, hydraulic conductivity) were measured using unconfined compression and flexible wall penetration tests. Simultaneously, the mineral composition, functional groups, and microscopic morphology of the solidified lake sediment were analyzed using microscopic techniques (X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy + energy dispersive spectroscopy). The corrosion mechanism of landfill leachate on the solidified sediment liner material was investigated. Additionally, the breakdown behavior of heavy metal Cr(VI) within the solidified sediment liner barrier was investigated via soil column model experiments. The dispersion coefficient was computed based on the migration data of Cr(VI). Simultaneously, the detection of Cr(VI) concentration in pore water indicated that the solidified sediment liner could effectively impede the breakdown process of Cr(VI). The dispersion coefficient of Cr(VI) in solidified sediments is 5.5 × 10−6 cm2/s–9.5 × 10−6 cm2/s, which is comparable to the dispersion coefficient of heavy metal ions in compacted clay. The unconfined compressive strength and hydraulic conductivity of the solidified sediment ranged from 4.90 to 5.93 MPa and 9.41 × 10−8 to 4.13 × 10−7 cm/s, respectively. This study proposes a novel approach for the co-disposal and resource utilization of various solid wastes, potentially providing an alternative to clay liner materials for landfills.

Exploring the geotechnical and microstructural properties of composite mixtures for landfill liner materials: an experimental investigation.

The present study directs the need for the development of an economical composite mix comprised locally available soil and industrial waste which satisfy the design parameters of the municipal solid waste (MSW) landfill. The local soil, bentonite, and fly ash mixtures are mixed in different proportions to evaluate the geotechnical and microstructural characteristics for suggesting an optimum composite mix that fulfills the design parameters of landfill liners. The curing periods of different mixes are also considered while evaluating the unconfined compressive strength (UCS) characteristics. The microstructure of the mixtures is examined using advanced imaging techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDAX) to gain insights into the changes at the microscale level due to the inclusion of fly ash. It is observed that soil-bentonite-fly ash composite mix in a ratio of 65:15:20 aligns with the optimal design characteristics required for a landfill liner. Notably, for this composite mix, both liquid limit (LL) and plastic limit (PL) show a significant increase of 48.57% and 32.33% respectively, while the optimum moisture content (OMC) rises by 11.25%. Conversely, maximum dry density (MDD) experiences an 8.79% decrease. Moreover, the free swell index (FSI) escalates by 113%, whereas hydraulic conductivity (HC) records a substantial reduction of 96.04%. Moreover, the UCS exhibited a notable increase of 209% after a 28-day curing period. The highest strength is achieved initially by soil mixed with 20% fly ash, followed by a blend containing 15% bentonite. Therefore, proper fly ash content in filler and other binder materials is an effective and sustainable approach that not only solves the disposal issue but also enhances the material's engineering characteristics, justifying its suitability to be used as a landfill liner.

Utilization of Rubber Wood Ash–Clay Mixes as Bottom Liner Material in Solid Waste Landfills: Engineering Properties and Microstructural Characteristics

Utilization of Rubber Wood Ash–Clay Mixes as Bottom Liner Material in Solid Waste Landfills: Engineering Properties and Microstructural Characteristics

A feasibility study of fly ash and bentonite composite mix for assessing its suitability as landfill liner material

A feasibility study of fly ash and bentonite composite mix for assessing its suitability as landfill liner material

Preparation and characterization of high density polyethylene with TiO2 modified PEG 6000 filler as a landfill liner material

High-density polyethylene is an engineering polymer that is used in bottom liners of landfills. However, to be used in the environment application, it needs to have good mechanical and thermal qualities. Incorporation of inorganic fillers such as titanium dioxide into a polymer aimed at enhancing several features such as mechanical strength, thermal stability, and resistance to surface wear. In this study, HDPE preparation was carried out by adding TiO2 nanoparticles. TiO2 nanoparticles were synthesized using the precursor TiCL4 and then modified with the addition of PEG 6000. Furthermore, the resulting TiO2 was used as a filler in thermoplastic HDPE. Characterization of high-density polyethylene with TiO2 filler as a landfill liner material shows an increase in mechanical and thermal properties. The HDPE sample containing 8%wt filler had the highest tensile strength, measuring at 84.72 Mpa. In contrast, the use of 6wt% filler resulted in the lowest recorded tensile strength, measuring at 56.24 Mpa. The elastic modulus had its highest increase at 8 wt% TiO2, reaching a value of 729.33 MPa. However, the addition of 6 wt% TiO2 resulted in a notable decrease in elastic modulus, with a value of 522.79 MPa. Additionally, it was observed that the highest elongation at break was achieved with a 4% weight filler, resulting in a value of 49.37%. Similar to the reduction observed in the elastic modulus value, the elongation at break exhibited a substantial decrease of 39.22% upon the addition of 6wt% TiO2. DSC scan curves for both the fabricated nanocomposite systems clearly show that they are affected by the nanofiller and its percentage fraction. There was an increase in Tm1 in the composition of 8wt% TiO2, while an increase in Tm2 occurred in 2wt% TiO2. Therefore, HDPE which is given TiO2 filler has the potential to be used as landfill liner material.

Effect of collated fly ash, GGBS and silica fume on index and engineering properties of expansive clays as a sustainable landfill liner

The effect of supplementary cementitious materials (SCMs) such as fly ash (FA), GGBS and silica fume (SF) on the geotechnical index and engineering properties of expansive clays (EC) are studied in this research work. This manuscript aims to determine the workability (consistency limits (CL)), swellability (free swell index (FSI)), compaction properties, strength characteristics (UCS) and hydraulic conductivity (HC) of varied eighteen mix proportions of FA-EC (P-series), FA-GGBS-EC (Q-series) and FA-GGBS-SF-EC (R-series) are experimentally studied as a bottom liner in landfills. From the test results, CL and FSI significantly decreased in P, Q and R series, this is due to the effect of flocculation, a process that increases the average particle size of mix blends and also depletion of the double-diffusive layer thickness of EC by promoting the Ca2+ ions in the pore water from SCMs. The compaction parameters such as optimum moisture content decreased in all the series, due to the higher flocculation of mixes. However, maximum dry unit weight increased in Q and R and decreased in the P series. The UCS values increased with an increase in optimum SCMs quantities and with curing intervals tested at 0, 7, 14 and 28 days. The higher UCS value is attained at 40 %FA with EC (i.e. P2), 60 %FA-GGBS with EC (i.e. Q3) and 60 %FA-GGBS-SF with EC (i.e. R3) in R-series which confirmed to be optimum due to the loss of cementation action/reduced cohesion in the matrix. In the case of HC, P2, Q3 and R3 mixes are confirmed to be optimum and fall under the criterion standards of landfill liner as per USEPA recommendation. Overall, this work proves to be a novelty and shows the feasibility of various collated SCMs blended with EC as landfill liner material, furthermore, these mixes are optimized to combine with EC to create a sustainable landfill liner that fits with the United Nations sustainable goals of 2030

Evaluating the Potential of Multi-Walled Carbon Nanotube-Modified Clay as a Landfill Liner Material.

In this paper, the feasibility of multi-walled carbon nanotube (MWCNT)-modified clay as a landfill liner material is investigated. Experiments were conducted on the modified clay with 0.5%, 1%, and 2% MWCNTs. The effects of the MWCNTs on the compaction characteristics, permeability coefficient, stress-strain curve, peak deviation stress, shear strength parameters (internal friction angle and cohesion), microstructures, and adsorption performance of the clay were analyzed. The results showed that the optimum moisture content (OMC) increased from 16.15% to 18.89%, and the maximum dry density (MDD) decreased from 1.79 g/cm3 to 1.72 g/cm3 with the increase in MWCNTs. The permeability coefficients firstly fell and then gradually rose as the MWCNTs increased; the minimum permeability coefficient was 8.62 × 10-9 cm/s. The MWCNTs can also effectively increase the peak deviation stress of the clay, and at the maximum level, the peak deviation stress was increased by 286%. SEM images were processed using the Pore and Crack Analysis System (PCAS), and the results showed that the appropriate amount of MWCNTs could fill the pores and strengthen the clay structure. The effect of the MWCNT-modified clay on the adsorption performance of common heavy metal ions Cd2+, Mn2+ and Cu2+ in landfill leachate was analyzed by batch adsorption tests. The maximum adsorption capacities (Qmax) of Cu2+, Cd2+ and Mn2+ in the 2% MWCNT-modified clay were, respectively, 41.67 mg/g, 18.69 mg/g, and 4.97 mg/g. Compared with the clay samples without MWCNTs, the adsorption properties of Cu2+, Cd2+, and Mn2+ were increased by 228%, 124%, and 202%, respectively. Overall, the results suggest that MWCNT-modified clays have the potential to be suitable barrier materials for the construction of landfills.

Shrinkage and Consolidation Characteristics of Chitosan-Amended Soft Soil—A Sustainable Alternate Landfill Liner Material

Kuttanad is a region that lies in the southwest part of Kerala, India, and possesses soft soil, which imposes constraints on many civil engineering applications owing to low shear strength and high compressibility. Chemical stabilizers such as cement and lime have been extensively utilized in the past to address compressibility issues. However, future civilizations will be extremely dependent on the development of sustainable materials and practices such as the use of bio-enzymes, calcite precipitation methods, and biological materials as a result of escalating environmental concerns due to carbon emissions of conventional stabilizers. One such alternative is the utilization of biopolymers. The current study investigates the effect of chitosan (biopolymer extracted from shrimp shells) in improving the consolidation and shrinkage characteristics of these soft soils. The dosages adopted are 0.5%, 1%, 2%, and 4%. One-dimensional fixed ring consolidation tests indicate that consolidation characteristics are improved upon the addition of chitosan up to an optimum dosage of 2%. The coefficient of consolidation increases up to seven times that of untreated soil, indicating the acceleration of the consolidation process by incorporating chitosan. The shrinkage potential is reduced by 11% after amendment with 4% chitosan and all the treated samples exhibit zero signs of curling. Based on the findings from consolidation and shrinkage data, carbon emission assessments are carried out for a typical landfill liner amended with an optimum dosage of chitosan. In comparison to conventional stabilizers like cement and lime, the results indicate that chitosan minimized carbon emissions by 7.325 times and 8.754 times, respectively.

Hydraulic Conductivity Characteristics of Iron-Ore Tailings–Bentonite Mixtures Exposed to Landfill Leachate

Landfill liner materials are required to provide reliable hydraulic performance for very long times after construction, and at least for the design lifespan of the facility. To meet this objective, liner systems must retain their low hydraulic conductivity over their service lives. In this paper, we report on the durability aspects of iron-ore tailings (IOT)–bentonite mixtures in extended hydraulic conductivity experiments. The hydraulic conductivity tests were conducted on mixtures containing 20%, 25%, 30%, 35%, and 40% bentonite, compacted at 2% wet of optimum by the British standard light (BSL) effort, and permeated with municipal solid waste (MSW) landfill leachate (electrical conductivity = 25.60 mS/m, pH = 7.94) with or without prehydration for a duration of 120 days. Under these influences, permeation with leachate showed no detrimental effect on mixtures with 25% and 30% bentonite, but was rather beneficial in reducing the hydraulic conductivity (k) values of the two mixtures at the end of testing by two orders of magnitude to 4.19 × 10−8 and 9.25 × 10−9 cm/s for the prehydrated specimens and 2.4 × 10−8 and 9.9 × 10−9 cm/s for the nonprehydrated specimens. For mixtures containing 20%, 35%, and 40% bentonite, k values representing a 1.6 times decrease from the average were recorded for both the prehydrated and nonprehydrated conditions at the end of testing. Further analysis showed that prehydration had a slightly substantial effect on those specimens containing 20%, 35%, and 40% bentonite, whereas it had a minor effect, if any, on mixtures with 25% and 30% bentonite. In terms of durability, only mixtures containing 25% and 30% bentonite that consistently maintained low k values up to the end of testing are projected to be effective as liner materials in the construction of geological repositories for MSW. Regarding the hydraulic conductivity characteristics of the mixtures upon exposure to the combined effects of leachate and the elevated temperatures expected in landfill conditions, all mixtures maintained relatively good hydraulic performance, exhibiting a decrease in hydraulic conductivity with time.

Contaminant retention affected by controlled and uncontrolled pH for fly ash-bentonite composites used as landfill liner material

Contaminant retention characteristics of clay-based composites as affected by pH needs to be quantified for its design, functionality, and performance as a landfill liner material. The efficacy of four fly ash (FA) in bentonite-fly ash (B-FA) mixes was investigated for its lead (Pb2+) retention characteristics under controlled pH (pH = 5) and realistic uncontrolled pH conditions anticipated in the landfill liners. B-FA mixes with 30%, 50%, and 70% FA amendment, bentonite-sand (B–S) mixes, and parent materials were tested by batch sorption tests. Under uncontrolled pH conditions, the retention capacity of all parent materials and mixes was higher than the controlled pH condition due to significant precipitation reaction and complexation associated with pH. Beyond 1000 mg.L-1 initial concentration, B-FA mixes constituting FA with inherent pH > 10.5 were the most efficacious adsorbents. Under both pH conditions, the metal retention capacity of B-FA mixes was higher than that of conventional B-sand mixes. All results were analytically substantiated by detailed FESEM micrographs, XRD, and EDX spectra of samples before and after sorption. The Freundlich and Langmuir nonlinear retention model parameters indicate that the uncontrolled pH condition results in nonlinear sorption, the higher energy of sorption, and stronger interactive bonds between Pb2+ ions and sorbent.

Utilization of Kenaf Core Fiber – Marine Clay Mixture as a Landfill Liner Material

Nowadays, leachate production is a big concern and causes a serious hazard to the soil and groundwater which causes the subsurface soil to be polluted as a result of the loss of soil quality and environmental pollution. This study aims to study the potential of using kenaf core fiber and marine clay mixtures as improved landfill liner material. Relevant laboratory tests such as atterberg limit test, specific gravity test, and particle size distribution were performed to examine basic geotechnical properties of marine clay soil collected from Batu Kawan, Penang. Besides that, compaction test and hydraulic conductivity test were carried out for soil mixed with kenaf core fiber to determine the strength and permeability characteristics. The results found that the marine clay has significantly adequate physical properties to be used as a landfill liner. The permeability test for marine clay soil inclusion of kenaf core fibre indicated that the hydraulic conductivity of the samples admixture for 0%, 4%, 8%, and 12% ranged between 6.68 × 10-9 and 1.57 × 10-8 m/s. Compaction of marine clay mix kenaf core fibre samples resulted in maximum dry density, ρdmax that ranged between 0.936 and 1.595 g/cm3 and optimum moisture content, wopt that ranged between 19.8% and 24%. Hence the inclusion of kenaf core fiber in marine clay soil improves the maximum dry density value, decrease permeability of marine clay and could be potentially used for landfill liner material.

Effect of ammonia on the hydraulic conductivity and adsorption characteristics of lithomargic clay – bentonite barrier in landfills

Alteration of characteristic properties of the liner material occurs mainly due to interaction with contaminants present in the landfill leachate. The present study deals with the effect of inorganic contaminants on the behaviour of bentonite-based landfill liner material. Saturated hydraulic conductivity, unconfined compressive strength and compaction characteristics of the lithomargic clay and its blends permeated with an inorganic contaminant (ammonia) were evaluated. Experiments were conducted by blending lithomargic clay with 5%, 7.5% and 10% bentonite. The results showed that hydraulic conductivity decreased from an initial value of 3 × 10−8 m/s to 6.83 × 10−11 m/s. Unconfined compressive strength at wet of optimum and maximum dry density of blended lithomargic clay also reduced slightly. Adsorption studies were conducted, and the coefficient of distribution (Kd) for blended lithomargic clay with 5% and 10% was found to be 60.46 L/kg and 94.74 L/kg, respectively. The Kd values indicate good adsorption characteristics of bentonite-based material. Overall, the results showed that lithomargic clay blended with bentonite is a suitable alternative barrier for constructing engineered landfills to prevent environmental degradation and other health effects.

Mechanical Strength, Water Seepage and Microstructure of a Novel Landfill Solidified Sludge Liner Material

In order to prepare a novel landfill liner material, we used industrial calcium-containing waste (slag, fly ash, and desulfurized gypsum) to solidify municipal sludge. The mechanical and permeability properties of the solidified sludge material (SSM) were evaluated using straight shear, uniaxial compression, and permeability tests. The hydration products, microscopic morphology, and elemental composition of the SSM after the wet and dry cycles were analyzed using a combination of scanning electron microscopy (SEM + EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The SSM has high strength and low hydraulic conductivity. The values of cohesion c and internal friction angle φ reached 0.45–3.31 MPa and 6.52–36.28°. The SSM exhibited a compressive strength of 0.93–11.67 MPa and hydraulic conductivity of 4.80 × 10−9–1.34 × 10−7 cm/s. Analysis shows that SiO2, Al2O3, and CaO in industrial calcium-containing solid wastes and sludges produce dense bulk and agglomerated C-S-H and C-A-S-H gels under alkali excitation. The optimum ratio of sludge, desulfurized gypsum, fly ash, and slag in the solidified sludge was 1:0.61:0.62:0.54, whereas the optimum exciter was Ca(OH)2. The SSM may be used as a good barrier material to prevent water seepage in landfills.

Geotechnical behavior of fly ash-coal ash and bentonite clay composite as a landfill barrier material with special emphasis on desiccation cracks

Compacted clay barriers have been used to retard leakage of contaminated fluids from landfillsites. These liners may shrink, crack, desiccate and lose their integrity if the liner material doesn't have permeability (10−9 m/s), unconfined compressive strength (UCS = 200 kPa) and no desiccation cracks at all as per the CPCB-2001 and USEPA 1989 guidelines. These three parameters form the basis of utilizing any material as a liner material however bentonite clay (BC) due to excessive desiccation cracks upon drying and wetting events can't be used individually. The usual practice to overcome failure, of barrier material the usual practice is to amend BC with sand though being costly and unsustainable. Recently, Fly ash (FA) and Coal ash (CA) byproducts from thermal power plant, have been explored as a substitute of sand in landfill liner material for sustainable practices. The purpose of this study is to investigate and and compare the various composition of B-FA and B-CA in terms of adequate strength, permeability, and shrinkage/desiccation in such a way to meet the CPCB-2001 and USEPA 1989 guidelines. The variation of specific gravity, liquid limit, plastic limit, and DFSI with varying compositions of bentonite was also studied. The present study demonstrates that with the increment of BC permeability was found to decrease and 80CA20B, 80FA20B, 80FA15B5CA combinations were meeting CPCB-2001 permeability criterion. To replicate the field condition the overburdening pressure was varied from 100 to 800 kPa and the permeability was found to be within the prescribed range for the three compositions. In total, 72 UCS, including triplicates for 7, 14 and 28 days, were conducted to see if any pozzolanic reaction was ensuingand its effect on the strength. The maximum UCS was found to be 302 kPa for 80CA20B composition while 277 kPa for 80FA20B. Strength Improvement Factor (SIF) and Mobilized peak strain factor (MPSF) were found to be maximum for the 80CA20B composition for 28 days as 1.54 and 0.44 respectively. The composition 80CA20B demonstrated better desiccation crack resistance behaviour than 80FA20B and 80FA15B5CA. The volumetric shrinkage for 80CA20B, 80FA20B and 80FA15B5CA were 4.6, 10.49 and 4.2%. Further, there were no desiccation cracks observed if the volumetric shrinkage is around 4%. The water retention behavior of all the three compositions was almost same. The microstructure analysis for morphology, compositional characterization, and thermal analysis of the various constituents was also carried out.

Reliability-Based Design Optimization of Biopolymer-Amended Soil as an Alternative Landfill Liner Material

Reliability-Based Design Optimization of Biopolymer-Amended Soil as an Alternative Landfill Liner Material

Interaction of diesel oil contaminants with laterite soil and bentonite treated by sawdust -landfill liner

ABSTRACT Landfill liners blended with industrial by-product seems to outperform the conventional liners. This paper presents the influence of sawdust (SD) admixed with bentonite and locally available lateritic soil on consistency limits, free swell index (FSI), compaction characteristics, unconfined compressive strength (UCS), hydraulic conductivity and leachate characteristics. SD content was varied as 10%, 15% and 20%. Diesel oil contaminants (DOC) and deionised water (DIW) were used as the test fluids. From the test results, consistency limits, FSI, maximum dry density, leachate concentration of heavy metals and UCS decreased, whereas optimum moisture content and hydraulic conductivity increased with increasing sawdust content. Furthermore, the energy-dispersive X-ray spectrometer revealed the absence of calcium in the blends which have resulted in poor cementation and decreased the UCS. X-ray diffraction showed that the presence of cellulose in sawdust and montmorillonite in bentonite adsorb the heavy metals in DOC. Based on the test results, 15% Saw dust content in the blends proves to be the optimum in retaining the heavy metal concentrations, improving the geotechnical properties and qualifying as a landfill liner material.

Assessing the Swelling and Permeability Behavior of Novel Marble Dust–Bentonite with Sand–Bentonite Mixes for Use as a Landfill Liner Material

Assessing the Swelling and Permeability Behavior of Novel Marble Dust–Bentonite with Sand–Bentonite Mixes for Use as a Landfill Liner Material

Understanding the microstructure, mineralogical and adsorption characteristics of guar gum blended soil as a liner material.

Guar gum blended soil (GGBS) offers potentially advantageous engineering characteristics of hydraulic conductivity and strength for a soil to be used as a liner material. Characterization techniques such as X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy and scanning electron microscope were used to examine the mineral composition, functional groups and morphological changes in the unblended soil (UBS) and GGBS. These characterization approaches are used to understand adsorption-associated mechanisms of Pb(II) removal. Batch adsorption tests were performed to evaluate the adsorption capacity of UBS and the GGBS with various proportions (0.5%, 1.0%, 1.5% and 2.0%) of guar gum (GG) towards the removal of Pb(II) ions. Batch adsorption experiments were conducted by varying the pH, dosage of adsorbent, concentration of metal ions and contact time. The experimental results showed that the optimum removal of Pb(II) ions was high at a pH of 3.0 for all blends, and adsorption tests beyond 3.0 pH demonstrated a decline in adsorption performance. The maximum Pb(II) removal efficiency of 95% was obtained using the 2.0% GGBS. The isotherm model assessment for adsorption experimental data of Pb(II) showed the best fit for the Langmuir model on using GG. The present research demonstrated that the guar gum-treated blends exhibited potential Pb(II) ion adsorption properties and therefore can be used as sustainable liner material in sanitary landfills.

Effect on engineering properties of ground granulated blast furnace slag admixed with laterite soil, cement and bentonite mixtures as a liner in landfill

This paper showcases the geotechnical and environmental engineering properties of ground granulated blast furnace slag (GGBS, a byproduct of iron-ore) admixed with local laterite soil (LS), bentonite (BT) and cement (CT) mixtures as landfill liner. The main aim of this study is to determine the effect of GGBS on LS (i.e. effect of binder material with filler material) and to study the effect of GGBS-LS blended with varied BT and CT mixtures (i.e. binder-filler material in partial replacements), to perpetrate as a landfill liner material. Overall, a wide range of fifteen unique mix proportions was chosen in this study and are categorized into five series. Laboratory tests such as consistency limits, free swell index (FSI), Proctor compaction, hydraulic conductivity (HC), leachate characteristics (LC) and unconfined compressive strength (UCS) with post-testing analysis were conducted to evaluate the optimum mix. From the test results, the consistency limits and FSI decreased with an increase in GGBS content for all the mixes. In compaction tests, the addition of GGBS increases the dry unit weights and reduces the water contents. The HC decreased with the addition of GGBS quantities when permeated with deionized water and diesel oil as permeant fluids. In the LC, the concentrations of heavy metals (i.e. Cr, Co, Cd, Fe and Pb) in diesel oil decreased and removal efficiencies increased for lower HC values than higher HC values. The UCS values increased with an increase in GGBS quantities and curing intervals for all the mixes. The microstructure and mineralogical analysis revealed the identification and confirmation of new cementitious products which ameliorated the UCS values. Hence, from this study, when GGBS admixed with filler and other binder material established to be an efficacious and eco-friendly solution which not only reduces the disposal problem but improves the engineering properties and prerequisite as landfill liner.