Measurement and Enhancement of Plasticity Indices of some Extruded Ghanaian Clays

Abstract

The use of simple equipment that can reliably calculate plasticity indices of three local clays (Cape Coast, Fosu and Teleku Bokazzo) in both aqueous and organic media by extrusion method was studied. Experimental procedures were followed and one basic modification was made to Worrall and Khan measurement of rate of flow of plastic clays in order to prevent sud-den rush of compressed air. Results indicate that plasticity brought about by ageing can be measured for clays in aqueous and organic medium. Clays aged for a further period of six months in aqueous medium showed greater plasticity index values confirming the reliability of the measuring instrument. The study revealed that Teleku Bokazzo Kaolin in organic medium has high plasticity that can be exploited in various product developments especially in refractory production where low iron content clays are usually needed. Plasticity of local clays can be measured accurately and reliable plasticity indices can be controlled by the length of ageing time for consistent manufacturing results.