EFFECT OF CEMENT KILN DUST SUBSTITUTION ON CHEMICAL AND PHYSICAL PROPERTIES AND COMPRESSIVE STRENGTH OF PORTLAND AND SLAG CEMENTS

摘要

From the above results, it can be concluded that: 1. Addition of CKD increases the water for normal consistency of OPC and BFS cement pastes, whereas the setting time decreases. 2. Free lime content of CKD-OPC cement pastes increases sharply up to 7 days, and then increases more slowly, whereas, the free lime content of CKD-BFSC pastes increases with curing time for all cement pastes up to 7 days, and then increases with time. 3. The free water increases with the quantity of CKD. 4. The combined water content in the blended cements is less than that in OPC and BFS cement pastes. 5. The substitution of OPC with CKD up to 6 mass% has no significant effect on the compressive strength of hardened cement mortar. However, a CKD content of more than 6% adversely affects the compressive strength. A similar effect was noted in the slag cement. This indicates that CKD acts as an activator for slag cement hydration. The optimum value of CKD ranges between 5 to 10 mass%. At 15 and 20% CKD, the compressive strength of the slag cement decreases.