Investigation on geoengineering properties of organic silt soil treated with chitosan nanoparticle additive.

Organic soil deposits are often unsuitable for safely bearing structural loads without proper soil stabilization measures. Sustainable methods of soil stabilization are gaining attention, with nano-additives showing promising effects owing to their high reactivity and better soil interaction. The present study attempts to investigate the feasibility of treating a low-plasticity organic silt soil using chitosan nanoparticle (CNP) additive, a crustacean polysaccharide. The modifications in the soil plasticity index (PI), compaction, unconfined compressive strength (UCS), permeability and consolidation properties were studied for 0.5 to 2.5% CNP addition, considering the curing period durations of between 0 and 90 days. Results showed that 1% CNP addition produced a better outcome in terms of geoengineering properties. For instance, compared to the untreated soil, the compacted 1% CNP-treated soil achieved a 146% UCS gain and 69% permeability coefficient reduction for 90-day curing, with negligible change in the coefficient of consolidation. Whereas 2.5% CNP-treated soil exhibited a comparatively smaller UCS gain (of 100%), along with a 59% permeability coefficient reduction for 90-day curing. SEM analysis indicated that the CNP additive enhanced the geomechanical properties by forming a fibrous network in the soil matrix. Finally, a critical discussion has been presented on the aspects of necessity of nano-based soil stabilization, cost analysis and material degradation effects to understand the suitability of the technique for practical applications.