Strength and microstructural characteristics of lime-stabilized dredged soil reinforced with sugarcane bagasse fiber

The large-scale generation of high-water-content dredged soils presents significant challenges due to their low strength and high compressibility, limiting their direct use in engineering applications. This study investigates a sustainable stabilization approach by combining lime with sugarcane bagasse fibers (SBF) to enhance the mechanical performance and deformation characteristics of dredged soil. A comprehensive experimental program was conducted, including direct shear and unconfined compressive strength (UCS) tests under varying fiber contents (0- 2%) and curing periods (3 h, 7 d, and 28 d), complemented by scanning electron microscopy (SEM) to examine microstructural evolution. The results show that lime–fiber treatment significantly improves shear strength, cohesion, internal friction angle, and UCS compared to untreated and lime-only stabilized soils. An optimal SBF content of 1.5% was identified, at which peak strength and ductility were maximized. Compared with lime-only treated soil, the inclusion of 1.5% sugarcane bagasse fiber (SBF) increased cohesion by approximately 65.9% and significantly enhanced the unconfined compressive strength after 28 days of curing. The internal friction angle also increased with fiber inclusion, indicating improved interparticle interaction and resistance to shear deformation. In addition, fiberreinforced specimens exhibited enhanced ductility with peak axial strain increasing from approximately 3-5% to 5- 10%. Fiber inclusion increased axial strain at peak stress, indicating enhanced deformation capacity and reduced brittleness. Strength gains were more pronounced with curing time, reflecting the progressive development of cementitious products from lime-induced hydration and pozzolanic reactions. SEM observations reveal that strength enhancement arises from the synergistic interaction between fiber-induced interlocking and crack-bridging mechanisms and lime-induced bonding within the soil matrix. Excessive fiber content led to agglomeration and weak interfaces, slightly reducing strength. The findings demonstrate that lime-SBF stabilization provides an effective and environmentally sustainable solution for improving dredged soil for geotechnical applications.