Utilisation of local sand for testing cement and assessment of Mbeya pozzolana as partial replacement for ordinary portland cement

This dissertation deals with the study on the utilisation of local sand for testing the quality of cement. The study also aims at investigating the possibility of partially replacing ordinary portland cement by Mbeya pozzolana. Local sand is found to be very siliceous to the extent of about 97 per cent silica. Mpiji sand gave similar strength development in mortar as that of British standard sand. Tabata and Mbagala sands developed strength which showed deviation from that of British standard sand. Strength developed by mortar cubes prepared from local sand is correlated to that of British standard sand by a linear regression of the type y = BX + A. Chemical composition of Mbeya pozzolana used as partial replacement for ordinary portland cement was found to be within the limits of the general chemical composition of other pozzolanas in the world. Pozzolanic activity and compressive strength results of mortar cube specimens indicated that Mbeya pozzolana can partially replace ordinary Portland cement up to forty per cent. The replacement of ordinary portland cement can be done either by intergrading Mbeya pozzolana with cement clinker and gypsum or blending it with ordinary portland cement.