Mechanical Behaviour of Cement and Lime-Stabilised Laterite Subgrade at Various Matric Suctions

Considering the prevalent occurrence of unsaturated soil conditions above the groundwater table, this study explored the influence of soil stabilisation with chemical stabilisers—cement and lime—on the mechanical characteristics of unsaturated laterite soil. Initially, an unconfined compression test was carried out to identify the optimal dosages of cement and lime for stabilising laterite soil. The results indicated that 6% cement and 5% lime, with a 7-day curing period, were the optimal dosages according to the Malaysia Public Works Department specifications. Following this, a series of experiments were performed to assess the unsaturated mechanical behaviour of soil specimens stabilised with these dosages. These experiments utilised an automated, modified suction-controlled oedometer with the axis translation technique to maintain constant suctions of 20 kPa (representing wet conditions) and 400 kPa (representing dry conditions). The findings revealed that the impact of chemical stabilisation (bonding) was more significant on the mechanical behaviour than the effect of partial saturation (suction). Notably, soil stabilisation led to a substantial increase in pre-consolidation pressure, which resulted in a significant reduction in settlement of the investigated soil specimens.