Mechanical behavior and microstructural insights of bagasse fiber and fly ash-treated dredged clay

This research examines the synergistic influence of bagasse fiber (BF) and fly ash (FA) on the mechanical characteristics of dredged slurry with high water content. Unconfined compressive strength (UCS) tests, direct shear (DS) tests, and scanning electron microscopy (SEM) were performed under different BF dosages and curing durations. The results demonstrate that incorporating BF together with FA markedly improves both the strength and deformability of the treated slurry. When the BF dosage is 1.5%, the peak UCS of FA-stabilized specimens rises by about 22.5% relative to that with 0.5% BF, whereas further increasing BF beyond 1.5% leads to a reduction of nearly 7.5%. Shear strength also increases with BF content, with cohesion (c) and internal friction angle (φ) reaching their peak values at 1.5% BF and 20% FA. SEM analysis reveals that the stabilization mechanism of FA is mainly governed by pozzolanic reactions, which generate secondary cementitious phases and lead to a denser soil skeleton. BF forms a reinforcing network, improving tensile resistance and preventing crack propagation. The synergy between FA and BF maximizes soil strength, reduces brittleness, and enhances stability. This study provides a sustainable solution for utilizing dredged slurry in geotechnical engineering while promoting the efficient use of industrial byproducts.