Experimental study reveals improved compressive strength and cohesion in expansive black cotton soil using Grewia optiva fibers, indicating sustainable geotechnical soil reinforcement.
Key Points
To evaluate the feasibility and performance of Bhimal (Grewia optiva) natural fibers as a sustainable discrete reinforcement to improve the geotechnical strength and microstructural stability of expansive black cotton soil.
Tested expansive black cotton soil reinforced with discrete Bhimal fibers at varying contents (0.25%, 0.50%, 0.75%, 1.00%, and 1.25%) and lengths (15, 20, and 25 mm).
Conducted Modified Proctor compaction, direct shear, and unconfined compression tests to determine geotechnical parameters.
Evaluated fiber impact through two-way ANOVA, regression modeling, and scanning electron microscopy (SEM) for microstructural failure mechanisms.
The optimum configuration (0.50% fiber content, 25 mm length) increased maximum dry density by 10.46% (1.53 to 1.69 g/cm³) and optimum moisture content by 40.91% (11.00% to 15.50%).
Unconfined compressive strength increased by 22.30% (55.6 to 68.0 kPa) and cohesion increased by 18.63% (51.0 to 60.5 kPa), with ANOVA identifying fiber length as the more influential parameter.
SEM demonstrated crack-bridging, particle attachment, and pull-out mechanisms, while the classical UCS ≈ 2c relationship showed poor agreement with reinforced soil (R² = 0.088).