Stabilisation of Lateritic Soil Using Lime and Snail Shell Ash

Lateritic soils, predominantly found in tropical and subtropical regions, often exhibit poor geotechnical properties such as low shear strength, high compressibility, and high plasticity, making them unsuitable for direct use in construction activities without stabilization. This research explores the combined use of lime and snail shell ash (SSA) as innovative and sustainable stabilizing agents to enhance the engineering properties of lateritic soil. Lime, a traditional stabilizer, promotes pozzolanic reactions that enhance soil strength and durability, while snail shell ash, a byproduct of agro-industrial waste, provides an eco-friendly and cost-effective source of calcium oxide (CaO), a key component for soil stabilization. The study commenced with a comprehensive characterization of untreated lateritic soil to establish its baseline properties. Subsequently, soil samples were treated with varying proportions of lime (2.5%, 5%, 7.5%) and SSA (2.5%, 5%, 7.5%) by weight of dry soil, both individually and in combination. Laboratory tests conducted included particle size distribution, Atterberg limits, Proctor compaction, unconfined compressive strength (UCS), and California Bearing Ratio (CBR). The curing periods ranged from 7 to 28 days to evaluate the time-dependent pozzolanic reactions and strength gains. Results demonstrated that the combination of lime and SSA significantly improved the geotechnical properties of the soil. The plasticity index was markedly reduced, indicating enhanced workability. Maximum dry density (MDD) decreased, while optimum moisture content (OMC) increased, reflecting improved compaction characteristics. UCS and CBR values exhibited substantial increments, with the optimal performance achieved at a 4:6 lime-to-SSA ratio. The synergistic interaction between lime and SSA was attributed to the enhanced pozzolanic activity, leading to the formation of calcium silicate hydrate (C-S-H) and calcium aluminate hydrate (C-A-H) compounds, which are responsible for soil strength improvement. In addition to technical performance, the use of SSA addresses environmental concerns by repurposing agricultural waste, reducing dependence on conventional stabilizers, and lowering the carbon footprint of soil stabilization practices. This study underscores the potential of lime and SSA as complementary agents for sustainable soil stabilization, particularly in regions where lateritic soils are abundant and snail shell waste is prevalent. The findings contribute to advancing the knowledge of green construction materials and offer practical solutions for improving infrastructure in developing regions. Future work may focus on field-scale applications and the long-term durability of lime-SSA stabilized soils under varying environmental conditions.