The hydration heat development in blended cements containing up to 60% of fine-ground ceramics as Portland cement replacement is analyzed using an isothermal heat flow calorimeter. Experimental results show that the specific hydration heat of blended cements decreases up to two times, as compared with the reference Portland cement. The ceramics slightly retards the C3S hydration process but the first phase of C(3)A hydration and the dormant period are within the same time range for all analyzed ceramics contents. The replacement of Portland cement in the blended binder by fine-ground ceramics is found not effective for the ceramics amount higher than 20% by mass. Above this limit a substantial part of ceramics does not participate in the hydration process, and plays a role of a fine filler instead. The limited participation of the ceramics in the blended-cement hydration can explain the fast decrease in compressive strength and increase in the liquid water transport rate for the ceramics contents higher than 20%, which were reported before. (C) 2012 Elsevier B.V. All rights reserved.