Eco-Efficient Stabilization of Fine-Grained Soils Using Eucalyptus globulus Leaves to Improve Strength and Bearing Capacity

Soil stabilization is a critical challenge in civil engineering, particularly in regions with fine-grained soils prone to volumetric changes and reduced bearing capacity. In Peru's central highlands, unstable subgrades pose significant risks to infrastructure durability, making the development of sustainable reinforcement techniques essential. This study evaluates the effectiveness of Eucalyptus globulus leaves (EL) as a natural soil stabilizer, considering their availability and potential for improving mechanical properties. Dry and crushed EL, passing through No. 40 and No. 4 sieves, were incorporated into two soil types using an experimental design. Laboratory tests included Atterberg limits—liquid limit (LL), plastic limit (PL), and plasticity index (PI)—as well as unconfined compressive strength (UCS) and California Bearing Ratio (CBR), following standardized procedures. For the soil in Saños Chaupi (Sch), the LL increased with 5% EL inclusion. UCS values improved with a 2% EL increment, rising from 1.54 kg/cm² to 4.073 kg/cm². Similarly, CBR resistance increased by 2% and 3% EL, reaching values from 6% to 15.4%. However, both UCS and CBR showed a decline with 5% EL incorporation. Similar trends were observed in Parco (Pa). These findings demonstrate that Eucalyptus globulus leaves can enhance soil strength, particularly at optimal dosages of 2% to 3%. Their application as a natural stabilizer presents an eco-friendly alternative to conventional methods, reducing environmental impact while improving soil performance for construction purposes in the region.