Effects of Chemical Admixture on Flow and Strength Properties of Calcined Clay Used as a Supplementary Cementitious Material

Well-proportioned cement-based materials create durable, long-lasting infrastructure which benefit society. However lack of knowledge, availability, and interest result in many West African, Asia, and South American countries using natural or modified pozzolans without chemical admixtures. This study investigated powdered waste clay brick as a pozzolanic supplementary cementitious material (SCM). The calcined clay material was used to replace cement by weight at 10%, 20%, 30% and 40%. Consistent flow was achieved using a polycarboxylate high range water reducing admixture (HRWR). The results indicate that the application of HRWR increased the flow of calcined clay and Portland cement mortar mixtures. The maximum strength obtained for mixtures between Portland cement and calcined clay mortars was 30% replacement of cement by the calcined clay product. The study showed that a well-proportioned mortar mixture could reduce Portland cement content and CO2 significantly without compromising the strength and flow properties of the original mixture.