Suitability of Enset Fiber with Coffee Husk Ash as Soil Stabilizer

Expansive soil is a problematic soil due to swelling and shrinkage behavior during moisture variation. Damage to shallow foundations like pavement and footings of residential houses occurred due to these soils. Different scholars deal with stabilizing expansive soils using different mechanisms. This study also evaluated the suitability of Enset fiber with coffee husk ash materials to improve the expansive property of soils found in Jimma town. Different geotechnical parameters were determined for virgin soil and coffee husk ash with virgin soil. After treating the natural soil with varying percentages of coffee husk ash (5%, 10%, 15%, and 20%), the optimum levels of coffee husk ash were determined. Different laboratory tests such as CBR value, compaction test, and Atterberg limits were determined using the optimum coffee husk ash with varying percentages of enset fiber (0.3%, 0.6%, 0.9%, and 1.2%). The study reveals that the addition of coffee husk ash to enset fiber significantly increases the shear strength of expansive soils. With the addition of 15% of coffee husk ash and 0.9% of enset fiber, all tested geotechnical parameters improved the expansive soils to be used as subgrade materials. The soil changed from highly swelled material to poorly swelled material. Therefore, it can be concluded that the reuse of agricultural waste of coffee husk ash with enset fiber is applicable for expansive soil stabilization since it can improve the engineering strength of expansive soils and it is an economic and environmentally friendly material.