Investigation of Soil Index Properties in Ajalli and Its Environs in Anambra State, Nigeria

Abstract

In order to ascertain the engineering properties and erosion susceptibility of the soils in Ajali and its surroundings in Southeastern Nigeria, this study offers the geotechnical evaluation of those soils utilizing Particle Size Distribution (PSD) and Atterberg Limit analyzes. Six soil samples were taken from significant borrow pits in Ajali, Enugwu-Abo, Ufuma, Ndiowu, Isi-Ulo, and Ndikelionwu, where building supplies are frequently obtained for foundation and road construction. The particle size distribution, specific gravity, liquid limit, plastic limit, and plasticity index of the soils were determined through laboratory analyzes carried out in compliance with established geotechnical methods. According to the results of the particle size distribution, medium- to coarse-grained sands make up about 85% of the soils' weight, with fine-grained sand and coarse silt making up about 14% and 1%, respectively. The soils range from very poorly sorted to moderately sorted, indicating variations in depositional and textural characteristics. The average specific gravity value obtained is 2.67, which is typical of lateritic and sandy soils derived from sedimentary formations. Atterberg limit results showed average values of 63.45% liquid limit, 19.13% plastic limit, and 44.33% plasticity index, indicating moderate to high plasticity with appreciable intergranular cohesive strength. The predominance of sandy fractions suggests high permeability and weak resistance to erosion, particularly in areas dominated by non-plastic or weakly plastic soils. However, the moderate clay content observed in some locations contributes to improved cohesion and reduced susceptibility to particle detachment. The study concludes that the soils possess varying engineering behaviors, with moderate suitability for construction purposes but significant vulnerability to erosion and land degradation in poorly consolidated zones. The findings provide useful baseline information for geotechnical design, erosion control, road construction, and sustainable land-use planning within Ajali and its environs.