stress-strain behavior of heavy metal-contaminated sand-clay mixtures stabilized with carbonate

The leakage of heavy metals from pipelines, chemical storage, and industrial waste in response to industrialization and suburban development is a significant environmental concern. these heavy metals can profoundly impact the geotechnical properties of clayey soils, notably shear strength and soil microstructure, which play a crucial role in the design of landfills and buffer liners. due to the susceptibility of clay liners to shrinkage cracks, compacted sand-clay mixtures (scm) are preferred in landfills. thus, this research aims to investigate the unconfined compressive strength characteristics of various scm contaminated with three lead concentrations (0.1, 0.2, 0.5 mol/l). three types of clay including bentonite, kaolinite, and zeolite were used to study the shear behavior of scm for liners. additionally, the impact of sodium carbonate additives as a remediation technique for the contaminated soil was assessed. results indicate that sodium carbonate enhances the shear strength of heavy metal-contaminated sand-kaolinite mixtures (skm), while it reduces the shear strength of contaminated sand-bentonite mixtures (sbm). the differential behavior of skm and sbm is attributed to the respective changes in diffuse double layers. despite bentonite having a larger specific surface area, the primary characteristic of sand-kaolinite-bentonite mixtures (skbm) is governed by bentonite. consequently, the addition of sodium carbonate to contaminated skbm results in a slight reduction in peak axial stress. furthermore, although the compressive strength of contaminated skm is significantly reduced with the introduction of 5% zeolite, the incorporation of sodium carbonate in the mixture restores its strength. from a practical standpoint, while carbonate treatment improves the performance of buffer liners against heavy metal contamination, the remediated soil may not be suitable for load-bearing purposes.