Compressive strength and workability of concrete using natural pozzolana aspartial replacement of ordinary portland cement

The increasing cost and scarcity of portland cement has impacted negatively on the delivery of affordable housing and infrastructural development in developing countries like Ghana. This study investigated the use of natural clay pozzolana as partial replacement of portland cement in the production of concrete. Concrete cubes measuring 150mm 150mm 150mm were made from six different concrete mixes prepared by using pozzolana to replace 0%,10%, 20%, 30%, 40% and 50% of portland cement by mass. The workabilities of the fresh concrete mixes were evaluated using the slump test and compacting factor test while compressive strengths of concrete cubes were evaluated at 7, 14, 21 and 28 days. The maximum compressive strength at all ages of testing was obtained at 30% replacement, corresponding to an increase of 3%,12%,24% and 19% compared to the 7-day, 14-day, 21-day and 28-day compressive strengths. Workability decreased with an increase in replacement percentage. Pozzolana can be used to partially replace ordinary portland cement in the production of concrete without compromising strength.