The Effect of Coir Fiber on the Geotechnical Properties of Clayey Soil, in Wudil, Northwest, Nigeria

Various Geotechnical soil test which includes particle size distribution, Atterberg’s limit test, specific gravity test, compaction test, California Bearing Ratio (CBR) test and shear box test were carried out to investigate the effect of coir fiber on the geotechnical properties of clayey soil, with specific emphasis on its bearing capacity in Wudil, Northwest, Nigeria. The particle size distribution test result indicated that the soil sample from Wudil contains 14% clay. Additionally, the Atterberg’s limit test showed that the inclusion of coir fiber significantly impacted the soil's properties. Specifically, the liquid limit, plastic limit, and plasticity index of the clayey soil showed notable improvement with the addition of coir fiber compared to the untreated soil. The specific gravity of the soil saw no increase but fluctuated at different coir fiber treatment as the value before the mix which was 2.48 was more than those of the fiber mixtures. During the CBR test, the application of 3cm average length of coir fiber at different percentage of 0.5%, 1%, 1.5%, 2%, 2.5% and 3% to the soil shows a significant improvement as the CBR values are found to be 7.25, 7.79, 11.3, 12.35, 14.89 and 14.68% respectively, which is more than 6.71% of the soil without mix. At different treatment of 0.5%, 1%, 1.5%, 2%, 2.5% and 3% coir fiber, shear box test shows an increase in cohesion and the frictional angle of the soil, as well as significant increase in the shear strength. This implies that coir fiber is an effective reinforcement material, which is capable of strengthening the soil structure and enhancing the bearing properties of clayey soil.