COMPARATIVE ANALYSIS OF GEOTECHNICAL PROPERTIES OF SELECTED POTTERY CLAYS IN EKITI AND KOGI STATES OF NIGERIA

Abstract

The research work was able to analyse the geotechnical properties of pottery clay in Ekiti and Kogi States and to determine the clay properties required for establishing a small scale pottery industry. The research work was carried out by collection of disturbed soil samples from six different towns (Itagidi in Ofu local government area and Oga in Yagba local government area) in Kogi State and (Ire Ekiti in Oye local government area, Ara Ekiti in Ijero local government area, Igbara-Odo in Ekiti South West local government area, Isan Ekiti in Oye local government area) in Ekiti State. Grain size distribution of the samples was determined along with the specific gravity. All the tests were carried out at Geotechnical Engineering Laboratory in FUTA except X-Ray diffraction which was carried out in Sheda Science and Technology Complex Sheda, Abuja. Direct shear tests were carried out on the samples at 0.001mm/min rate of strain and at vertical pressures of 50kN/m2, 100kN/ m2, 150kN/ m2, and the results obtained shows the angle of shearing resistance of ф and cohesion, c as follows: c = 12.5kN/ m2, ϕ = 29° (Oga);c = 8kN/ m2, ϕ = 27° (Isan); c = 5kN/ m2, ϕ = 29°(Ara);c = 17kN/ m2, ϕ = 26° (Ire); c = 9kN/ m2, ϕ = 25° (Igbara Odo); c = 8.5kN/ m2, ϕ = 27° (Itagidi). Triaxial (Consolidated Undrained) tests with pore water pressure measurement were also carried out on all the samples at 0.005mm/min rate of strain, at the following confining pressures (minor principal stress); 100kPa, 200kPa, 300kPa, the effective angle of internal friction ϕʹ and cʹ was obtained: cʹ = 33.6kPa & ϕʹ = 45.5°(Oga); cʹ = 120.9kPa & ϕʹ = 28.3°(Isan); cʹ = 82.2kPa & ϕʹ = 30.2°(Ara); cʹ = 112.5kPa & ϕʹ = 31.9°(Ire); cʹ = 137.5kPa & ϕʹ = 24.1°(Igbara Odo); cʹ = 104.3kPa & ϕʹ = 23.5°(Itagidi). Compaction Characteristics was also determined: Optimum Moisture Content (OMC) and Maximum Dry Density (MDD) gives the following values for the samples 21 & 1476kg/m3 (Oga), 18.7 & 1554kg/m3 (Isan), 23 & 1380kg/m3 (Ara), 15.5 & 1630kg/m3 (Ire), 19 & 1385kg/m3 (Igbara Odo) and 11.2 & 1485kg/m3 (Itagidi) respectively. California Bearing ratios for all the samples were determined and the respective bearing capacity of the soil shows Oga – 11.0%, Isan – 9.0%, Ara – 14.0%, Ire – 7.0%, Igbara Odo – 5.0% and Itagidi – 13.0%. X – ray diffraction analysis were carried out on the fraction of the soil passing No. 200 B.S Sieve using Air dried preferred Orientation. The presence of Kaolinite was confirmed by the following peaks: 7.20Å, 4.47Å, 3.58Å. Quartz was confirmed with the following reflections: 3.34Å, 2.45Å, 1.37Å. The presence of Illite, Halloysite, Chlorite, Feldspar and Chrysolite also was confirmed at different peaks; hence the pottery clays in Ekiti and Kogi States are generally good materials for different purposes in engineering fields.