The demand for sustainable soil stabilizers has driven interest in soil–biochar mixtures for geotechnical applications such as landfill liners and subgrade systems. However, the role of biochar particle size in governing compressibility, shear strength, and heavy metal immobilization remains unclear. This study examines the influence of fine (FB) and coarse biochar (CB) derived from bamboo on the compressibility, shear strength, and Pb2+ immobilization in clayey soil at dosages of 1–10%. One-dimensional consolidation tests reveal that FB at 10% increased the void ratio by 31.7%, whereas CB reduced it by 22.7% relative to untreated soil. Both biochar types decreased compression and swell indices at higher dosages, with FB-treated soils exhibiting greater stiffness under elevated stress. Void index analysis indicates the formation of a stable and stress-resistant soil–biochar matrix. Microstructural observations show denser particle packing in FB mixtures, while CB mixtures exhibit particle fragmentation at higher dosages. Toxicity characteristic leaching procedure (TCLP) tests demonstrate that 5% FB reduces Pb2+ concentrations below regulatory limits within 14 days, whereas CB requires higher dosages or longer curing periods. These findings highlight the critical role of biochar particle size in optimizing soil performance and contaminant immobilization for barrier applications.
Mohammad Nuruddin, A. Moghal, B. Dubey et al.· Scientific Reports· 0 citations
This study investigates the influence of guar gum (G), xanthan gum (X), and their cross-linked blend on the shear strength and consolidation characteristics of soils with contrasting plasticity and mineralogical characteristics. Direct shear, one-dimensional consolidation, constant head permeability tests, SEM and XRD analyses were conducted on high-plastic clay, medium-plastic clay, and sand-dominant soil treated with standalone (2G, 2X) and combined (1G+1X) biopolymer dosages under curing periods up to 28 days. The cross-linked treatment produced the most consistent overall improvement. In the high-plasticity soil, cohesion increased from 56.87 to 81.39 kPa and the friction angle increased from 7.8° to 10.5°. In the medium-plasticity soil, cohesion increased to 77.47 kPa and the friction angle reached 12.2°. In the sand dominant soil, the friction angle increased from 39.1° to 42.9°, while cohesion increased from 12.74 to 23.53 kPa. At 800 kPa, the cross-linked blend reduced the void ratio to 0.18 and 0.14 in the high- and medium-plasticity soils, respectively. Hydraulic conductivity decreased to 8.45 × 10⁻⁹, 8.21 × 10⁻⁹, and 9.10 × 10⁻5 cm/s in the three soils. These improvements are attributed to polymer bridging, hydrogen bonding, pore filling, hydrogel formation, and mineralogy-dependent soil-polymer interactions. The findings demonstrate the potential of cross-linked biopolymers as sustainable stabilizers for geotechnical applications.
M. A. Kumar, A. Moghal, B. Dubey et al.· Scientific Reports· 0 citations
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