<p>Soil stabilizers of natural origin are preferred over conventional stabilizers like cement and chemicals owing to energy-intensive production methods and the pollution that is caused during the production process. The need of the hour is to promote natural stabilizers that address environmental concerns. This study explores the possibility of improving the geotechnical properties of clay using calcium metasilicate (calsil). The effect of calsil on select geotechnical properties like consistency limits, compaction characteristics, strength and subgrade strength was investigated. The liquid and plastic limit of the soil increased marginally with the addition of calsil owing to its hydrophilic nature. The calsil-stabilized soil exhibited nearly a 17-fold increase in strength after 90&#xa0;days of curing. The crystalline structure of wollastonite facilitates a gradual, regulated release of calcium and silicate ions into the pore water, thereby reducing quick setting and permitting prolonged reaction times. Octahedral Al-O bond in ettringite mineral, Si–O stretching of silica and clay minerals,&#xa0;were influential in cementitious interactions with the clay soil. The crystalline lattice of wollastonite can engage with siliceous soil minerals at a microstructural level and functions as a nucleation zone for secondary reaction products, hence improving soil bonding. The presence of calcium silicate hydrate (C–S–H) in the calsil-stabilized clay contributed to the significant increase in strength. The calsil-stabilized soil achieved a cost reduction of 12.3% and a 15.4% decrease in CO₂ emissions, attributable to the decreased thickness of the bituminous and granular layers, promoting sustainability.</p>