Mineralogical and Physical Characterization of Some Clayey Soils from Parts of Southwestern Nigeria for Ceramic Application.

Abstract

Clayey soils have long been utilized in various industrial applications, particularly in the production of ceramics. The physical and mineralogical properties of these soils control their intrinsic behavior, which plays a vital role in determining their suitability for industrial applications. This study aims to explore the mineralogical and physical properties of selected clayey soils from Ekiti state in southwestern Nigeria and assess their implications for ceramic applications. The XRD analysis revealed that the soils contain kaolinite and illite as the dominant clay minerals, with significant quantities of quartz as well as considerable percentages of muscovite and goethite. Physical tests indicate that the soils consist of clays, silts, sand, and a subordinate amount of gravels, while the range of clay-sized particles suggests that the soils would not exhibit excessive shrinkage during firing. The plasticity chart reveals that the soils plot in the domain of medium to high plasticity and compressibility. Additionally, most of the clays studied presented liquid limit values in the range defined for raw clayey materials designated for ceramic applications. Moreover, the plasticity index of the clayey soils suggests that they are unlikely to be susceptible to inappropriate extrusion process. The position plots of the clayey soils on the workability chart indicate that the linear shrinkage of these samples would require some amendments prior to their processing. Furthermore, the high linear shrinkage exhibited by the soils could result in deformation and microcracking during the production of bricks, thereby requiring the addition of degreasers to reduce the plasticity of the clays before utilization. A general reduction in the water adsorption capacity with a corresponding increase in the firing temperature was observed. This could significantly affect the durability and mechanical characteristics of the soils. The flexural strength (FS) of the studied soils generally increased with increased firing temperature suggesting that the technological property is highly dependent on the temperature of firing.