Combined Effect of Reinforced Katcha Fiber, Kerosene, and Natural Sand in Improving the Engineering Properties of Clay Soil

Abstract

This study investigates the impact of reinforcing weak subgrade clay soil (WSCS) from the Koye Feche road project in Addis Ababa, Ethiopia, using natural fiber (katcha), kerosene, and sand. Various combinations of katcha fiber content (0.5%, 1%, and 1.5%), kerosene‐soaked katcha fiber lengths (20, 35, and 50 mm), and sand percentages (10%, 15%, and 20%) were tested to determine their effects on the soil’s performance. Unconfined compressive strength (UCS) and California Bearing Ratio (CBR) tests were conducted to identify the optimum mix. Results indicate that the maximum UCS value is achieved with 1% katcha fiber content, 35 mm katcha fiber length, and 20% sand content. The plasticity of the optimum mix decreases to 31.46%, while its strength increases to 59.75% compared to the untreated subgrade clay soil. The reinforced soil demonstrates durability comparable to conventional materials, with a cost‐saving of 40.71% over traditional replacement methods. This suggests the viability of reinforced soil in pavement construction, offering enhanced performance and economic benefits.