Lysimeters are frequently employed to replicate environmental conditions in landfill scenarios due to their relatively economical nature and brief study duration. Lysimeters frequently exhibit varying geometrical characteristics that modify the physical and thermodynamic attributes, potentially influencing waste material's decomposition rate and leaching dynamics. Based on the results of the lysimeter tests, lysimeters effectively evaluate and predict the impact of magnesium oxide (Mgo), a material suitable for constructing landfill liners. The findings substantiate that lysimeter investigations can significantly contribute to landfill engineering by identifying optimal strategies for waste containment and selecting appropriate materials for fabricating landfill barriers. Throughout the experimental procedure, the lysimeter was subjected to leachate application. In each hour of the experiment, the quantities of moisture, electric conductivity value (EC), temperature, settlement, pressure reaching the liner, and the total volume and pH of the obtained effluents were measured each week. This research explores and analyzes the role of magnesium oxide (C-M) in reducing permeability and measuring the shear strength properties of the composite material by utilizing a triaxial test. The sensor results demonstrated that MgO-enhanced liners provided superior long-term performance compared to clay. EC sensors showed MgO liners had lower and more stable conductivity. Moisture content sensors indicated that MgO-treated soil maintained better moisture regulation, reducing leachate. LVDT sensors revealed that MgO liners had minimal settlement, while clay experienced greater and prolonged settlement. Temperature sensors confirmed MgO's consistent thermal stability. In contrast, pressure, Total Dissolved Solid (TDS), pH, and flow rate sensors highlighted MgO's better structural integrity, lower dissolved solids, and controlled permeability over time.

This study aims to enhance the suitability of expansive clayey soils for use as landfill liners by incorporating water treatment sludge ash (WTSA). Expansive soils, prone to swelling and desiccation cracking, compromise landfill liner integrity, increasing the risk of groundwater contamination. Local soils often do not meet the requirements for hydraulic conductivity and stability, prompting the use of additives like bentonite. However, bentonite-treated soils still face challenges in tropical regions due to moisture loss and cracking. This research investigates the effects of adding WTSA to bentonite-treated soils to mitigate swelling and shrinkage issues. Several geotechnical tests were conducted, including hydraulic conductivity, free swell percentage, swelling pressure, volumetric shrinkage, and desiccation cracking. Results show that WTSA significantly reduces hydraulic conductivity, free swell percentage, and swelling pressure, meeting the standard requirements for liners (hydraulic conductivity of at least 1x10-9 m/s and volumetric shrinkage of at least 4%). Moreover, WTSA addition reduces desiccation cracking to acceptable levels, demonstrating its potential as an effective reinforcement material. This study introduces an innovative approach to using WTSA, a waste product, as a sustainable alternative to conventional liner materials, reducing environmental impact and enhancing landfill liner performance.

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 x 10-6 cm2/s-9.5 x 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 x 10-8 to 4.13 x 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.

This study comprehensively explores the compaction and compressibility characteristics of snail shell ash (SSA) and ground-granulated blast-furnace slag (GBFS) in stabilizing local bentonite for landfill baseliner applications. The untreated soil, with a liquid limit of 65%, plastic limit of 35%, and plasticity index of 30%, exhibited optimal compaction at a moisture content of 32% and a maximum dry density of 1423 kg/m3. SSA revealed a dominant presence of 91.551 wt% CaO, while GBFS contained substantial 53.023 wt% SiO2. Treated samples with 20% GBFS and 5% SSA exhibited the highest maximum dry density (1561 kg/m3) and optimal moisture content (13%), surpassing other mixtures. The 15% SSA-treated sample demonstrated superior strength enhancement, reaching an unconfined compressive strength of 272.61 kPa over 28 days, while the 10% GBFS-treated sample achieved 229.95 kPa. The combination of 15% SSA exhibited the highest shear strength (49 kPa) and elastic modulus (142 MPa), showcasing robust mechanical properties. Additionally, the 15% SSA sample displayed favourable hydraulic conductivity (5.57 x 10-8 cm/s), outperforming other mixtures. Notably, the permeability test, a critical aspect of the study, was meticulously conducted in triplicate, ensuring the reliability and reproducibility of the reported hydraulic conductivity values. Treated samples with SSA and GBFS showed reduced compressibility compared to the control soil, with the 15% SSA-treated sample exhibiting a more consistent response to applied pressures. Scanning Electron Microscopy analysis revealed substantial composition changes in the 15% SSA mixture, suggesting its potential as an effective base liner in landfill systems. In conclusion, the 15% SSA sample demonstrated superior mechanical properties and hydraulic conductivity, presenting a promising choice for landfill liner applications.

The paper presents the research of lime-softening sludge geotechnical properties when using it to construct landfill liners. The physical and mechanical properties of the lime-softening sludge test results are shown. The particle size analysis of the sludge, the specific density of solids of the particles and the specific surface area as well as the consistency limits and the sludge's compactibility have been determined in laboratory conditions. The tests of mechanical properties such as shear strength, uniaxial compressive strength and tensile strength have been carried out. A particular impact has been put on the sludge hydraulic permeability affected by the sludge moisture content and compaction. The synthetic analysis of the results revealed that the lime-softening sludge, in some determined conditions of building in and maintenance, meets the requirements for the landfill liners of the waste disposal sites and could successfully replace the natural soils in waste-landfill liners. A chart for constructing landfill liners made of sludge has been proposed.