Evaluation of Pozzolanic Activity of some Clays in Ghana

Abstract

A study of pozzolanic activity of four Ghanaian clays is presented. The moisture content, particle size distribution. and the chemical composition of clays were determined. X-ray diffractometric and thermal analysis were also performed to determine the mineralogical composition. Calcinations of the Oars were carried out at different temperature between 600-100^oC'r and the pozzolanas produced used to replace 20% Portland cement by mass in mortars. Compressive strengths of I:3 pozzolana cement mortar cubes at :28 days were determined. The values obtained showed that Asokwa(AS) and Mankesim (MN) clay samples become highly pozzolanic at 800°C whilst Hwereso (HW) and Nkosia (NK) days had their optimum calcination at 900°C and 6410°C respectively The compressive strengths were higher than the 24.1 N/mm minimum standard set for concrete and general construction.