Characterisation of Index Properties of Lateritic Soils in Ado Ekiti South Western, Nigeria

The aim of this research is to evaluate the index properties of lateritic soils in Ado Ekiti Area of Ekiti State, Nigeria. The areas will be divided into Five Zone viz Ado-poly, Ado-Ikere, Ado-Housing, Ado-Ilawe and Ado-Adebayo respectively for the sampling process. Eighteen soils samples were collected to cover Ado-Ekiti and environs in Ado Ekiti suburbs. The research comprise field data collections. ArcGIS 10.1 will be used for quantitative analysis of the field data. Measurement of depth at sample collection points will be taken using GIS, the geographic coordinate and other details using Global Positioning System (GPS) handheld instrument (Garmin 76). Laboratory test such as Natural Moisture Content (NMC), Specific gravity, Grain size analysis, Liquid Limit, Plastic Limit, Linear Shrinkage, All the analyses were carried out in accordance with the British Standard code of practice (BS13771990). The visual soil profile description of all trial pits investigated, reveal little variation within the soil strata. The laboratory results indicated that the particle size gradation for gravel ranged from 1 to 44 %, sand ranged from 26 to 77 % and fines ranged from 8 to 46 %, natural moisture content ranged from 1.1 to 18.7 %, specific gravity ranged from 2.23 to 2.79, the bulk density ranged from 1134. to 1625. kg/m3, , the liquid limit ranged from 25 to 65 %, plastic limit ranged from 17 to 43 %, plasticity index ranged from 10 to 30 %, linear shrinkage ranged from 3.6 to 15.5 %, According to America Association of State Highway and Transport Officials (AASHTO) soil classification and Unified Soil Classification System (USCS), all the samples can be classified as follows for all the five zone investigated A-2-4, A-2-6, A-6, A-7-5 for (AASHTO) and CL, MH and CH materials which describe the materials as Silty gravelly sandy soil, Clay of low Compressibility and Clay of High Compressibility. They satisfy Nigeria Specification for Road and Bridges requirements for subgrade, sub base and base course materials. Similoluwa samples, NTA samples, Adebayo samples and Falegan samples will be suitable only for base course, sub base course, earth dam and fills except for samples from poly and Abuad that are classified as unsuitable materials while other location will be considered suitable for sub grade materials. Conversely this research work has provided data for engineers, designers and contractor for the use of this lateritic soils materials for construction work and has prevented possible difficulties, delays and additional expenses during construction due to inadequate geotechnical information within this metropolis It is recommended that all contractors should ensure that the testing and quality control of lateritic materials and project site within this area is done before the commencement of work on site.