Dynamic Shear Resistance and Compressibility Mitigation of Berea Red Soil Through Biopolymer Stabilization and Sisal Fiber Reinforcement

Abstract This study investigates the use of biopolymer stabilisation in combination with sisal fibre (SF) reinforcement to improve the dynamic shear resistance (DSR) and reduce the compressibility of Berea Red Soil (BRS). The investigation evaluates the dynamic shear strength and compressibility, known as key attributes of subgrade performance. Oedometer and dynamic shear tests were conducted on the BRS samples with varying biopolymer concentrations and fibre contents. The performance metrics, including the DSR and Coefficient of Compressibility, were analysed to evaluate improvements in the subgrade response. The reinforcement technique produced notable gains in dynamic shear resistance, with some samples demonstrating up to 86% enhancements relative to untreated BRS. This substantial increase is attributed to the enhanced resistance of SF against dynamic stress. In parallel, compressibility measurements indicated a significant reduction in soil deformability under compression loading, affirming the efficacy of the biopolymer inclusion in mitigating compressibility through particle bonding and cohesion improvement. These results underscore the potential of combining biopolymer stabilisation with sisal fibre reinforcement to develop a more durable and efficient subgrade material. The approach offers a sustainable and technically robust alternative for applications in geotechnical engineering, particularly where improved resistance to dynamic forces is requisite.