Improving the performance of ternary blended cements by mixing different types of fly ashes

For overcoming certain drawbacks characterizing both basic types of fly ashes (of high and low calcium content), different ash intermixtures consisting of two types of fly ashes were prepared. The principal idea lying beneath the effort presented herein is that beneficial assets of the one type of ash could compensate for the shortcomings of the other. Compressive strength development, pozzolanic activity potential and nature of hydration products of all tertiary cements were closely monitored and presented in comparison to the respective properties of the initial binary blends. Moreover, efficiency factors were calculated for all new systems and were further used to validate previously reported expressions describing Binary Fly ash-Cement (BFC) systems. In accordance with previous works, ternary fly ash systems examined here outperformed the respective binary systems almost throughout the curing period. Synergy between the different types of fly ashes was considered the main reason for the excellent performance of the tertiary mixtures. Results obtained indicate that previously developed analytical expressions, correlating active silica of SCMs and k-values, can be applied in the case of multicomponent ash systems as well. (c) 2007 Elsevier Ltd. All rights reserved.