Textural Characteristics of subsoils in the main campus of Akwa Ibom State University, Ikot Akpaden, Akwa Ibom State, Southern Nigeria

Abstract

The textural characteristics of soils are very useful indices of the potential mechanical behaviour of the soil. These properties are used to identify and classify soils, prior to construction. Soils in nature usually contain varying proportions of gravel, sand, silt, clay or organic matter, they rarely exist separately. The aim of this study is to evaluate the textural properties of shallow subsurface soils, in six different locations within the main campus of Akwa Ibom State University, which serve as foundations for office buildings and roads. Field investigations including the drilling of six geotechnical boreholes to a depth of three maters each and laboratory analysis of the Moisture content, Particle size distribution, Atterberg limit and Compaction properties of the disturbed soil samples were performed. The  stratification of Sub soils from 0-3 meters in the six locations in the main campus of the University consist of reddish brown,  clayey, silty, fine to medium grained  sand  in locations L1, L2 and L3, while a light to dark brown,  clayey, silty, fine to medium grained  sand underlies  locations L4, L5 and L6. Laboratory analysis of the sub soils reveal low natural moisture content percentages of the soils which are generally below 30%.  The clay  have average liquid limit and plasticity index values  between 34% to 50% and 16% to 25% respectively and are of low to intermediate plasticity with a low swelling potential.  Particle size distribution of the soils, show they are poorly gradedsand. Optimum  moisture content and  maximum  dry density values of the soil show  location 4 has the lowest percentage of fines (40%),  the lowest optimum  moisture (8.3%) and highest maximum dry density (1830 kg/m³), while  location 5 has the highest percentage of fines (48%)  the highest optimum  moisture content (11.8%) and lowest maximum dry density (1740kg/m³).The maximum dry density values and optimum  moisture content percentages of the soils in all locations fall within the recommended range for good back fill materials. Although the textural properties of the subsoils show that the soils are all suitable for construction purposes, an increase in the density of the soils is recommended to improve its stability, using a suitable soil improvement method.