STATISTICAL EVALUATION OF SOILS INDEX PROPERTIES FROM SELECTED STATES IN SOUTHWESTERN NIGERIA

Abstract

Evaluation of index properties of soil samples is one the essential assessments soils proposed as construction materials are subjected to since it shed broad light on the class or group of soils. This study evaluates the Natural Moisture Content (NMC), specific gravity (Gs), grain size analysis, and Atterberg limits tests of soils in Ekiti and Osun, southwestern states of Nigeria. Soil samples were collected randomly from sixty (60) and ninety (90) locations in disturbed state from Osun and Ekiti state respectively. The laboratory tests conducted in accordance with the British Standard shows that soil samples within the states has a mean NMC, Gs, gravel content, sand, fines content, Liquid Limit (LL), Plastic Limit (PL), Plasticity Index (PI), and Linear Shrinkage (LS) of 11.52%, 2.31, 22.38%, 36.76%, 40.85%, 41.67%, 24.97%, 16.70%, and 7.32% respectively. Models were generated for the LL and PL, predicted using the specific gravity, fines and gravel contents of the soils. The metric evaluation of the models gave coefficient of determination of 0.4338 and 0.3165, mean absolute errors of 5.5577 and 4.1587, root mean square errors of 7.0800 and 5.1762 for LL and PL respectively. The p-value of the F-test, 5.95E-18 and 4.77E-12 for LL and PL respectively which are far lesser than 0.05 show that the models are statistically significant.