Mechanical Properties of Nano-Silica-Treated Organic Soil Reinforced with Banana Fiber

Nano-additives have proven the effects in geotechnical engineering through their application as soil-stabilizing material. The most abundant and commonly used nano-material is nano-silica. However, the literature shows that soil treated with nano-silica is brittle, which would cause sudden and catastrophic failure. On the other hand, fiber-treated soil showed better post-peak failure response than treated soil. Hence, the present work focuses on the performance of organic silt treated with banana fibers and nano-silica (of size 17 nm) through unconfined compression tests and permeability tests. The soil is treated with four different dosages of banana fibers, namely 0.25, 0.50, 0.75, and 1.00% by dry weight of the soil. The average aspect ratio of the banana fibers used is 10. Therefore, the optimum dosage of fiber is found to be 0.75%. Strength increases by nearly 17% with the addition of 0.75% banana fiber. Further, the soil has been treated with 0.75% of banana fiber and four different dosages of nano-silica ranging from 0.2 to 0.8% by dry weight of soil. Results of unconfined compression tests indicate that soil treated with 0.75% fiber and 0.4% nano-silica effectively improved soil strength. Also, the post-failure response was gradual rather than a brittle failure, as experienced in nano-silica-treated soil. The strength was enhanced by nearly 57% for the optimum dosage of fiber and nano-silica. The results of permeability tests showed a marginal rise in magnitude owing to the introduction of banana fiber and aggregation reaction of soil caused by nano-silica. This indicates that the soil medium tends to be well drained by adding fibers and nano-silica. Surface morphology analyzed through micrographs of scanning electron microscope shows that nano-silica created better aggregation in soil particles. The fibers acted as a bond in the aggregated soil mass. Hence, nano-silica helped enhance the soil strength, and banana fibers served as an aid to avert brittle failure in improved soil.