Friability and Erodibility of Ajali Formation-Derived Soils in Ngwo, Southeastern Nigeria: Geotechnical Implications
Abstract
Geotechnical challenges associated with erosion in the Ajali Formation at Ngwo, Enugu State, southeastern Nigeria, were assessed by characterizing the particle-size distribution, Atterberg limits, and X-ray fluorescence (XRF) of soil samples collected from exposures of the formation in the study area. Twenty samples were collected and analyzed but only four samples were for Atterberg limit test due lack of plastic materials in the majority of the samples. Particle-size distribution tests were conducted on all samples, and the results show average sand and fines contents of 88.98% and 11.04%, respectively, with average coefficients of uniformity and curvature of 3.27 and 1.11, respectively. The soil samples have an average liquid limit of 31.8% and a plasticity index of 9.88%. XRF results indicate that silica (SiO2) dominates the elemental oxides, with relatively low concentrations of Al2O3 and Fe2O3. The soils are predominantly poorly graded and exhibit low to no plasticity and weak binding characteristics. The observed properties of the soils are indicative of high erosion susceptibility in the studied soils and, consequently, to the geotechnical challenges affecting engineering structures in the area.