Burnt clay waste as a pozzolanic material in Kenya

Building materials account for about 60 percent of the total construction cost of a house. Cement is one major element of the building materials that account for 20-35 percent of the materials cost and is the most important element since it binds the building together. In Kenya, there are two binders commonly used, i.e., Portland Cements (PC) and Lime. The Portland cements, which include Ordinary Portland Cement (OPC) and Portland Pozzolana Cement (PPC) are the most widely used cements because of their fast curing properties. The introduction of PPC has not reduced the cost of cement in the country and the use of alternative cements, which are cheaper specifically for masonry works, should be encouraged. This paper presents findings of on-going research work since 1998 on alternative cement blended with burnt clay waste pozzolana, which is a by-product from burnt clay products. The research findings show that burnt clay waste contains pozzolanic properties for production of alternative pozzolana cement. It is therefore, recommended that small scale production enterprises be set up in areas that produce burnt clay products in order to process the pozzolana from the wastes to produce alternative pozzolanic cement, hence reduce the cost of cement in construction. (Journal of Civil Engineering, JKUAT: 2002 7: 27-44)