Hydration kinetics analysis of cementitious paste composites produced by binary and ternary binder materials for potential use in massive concrete structures

In order to explore the applicability of different cementitious paste systems used for massive concrete structures, the hydration characteristics and mechanism of the binary and ternary cementitious paste systems in Portland cement pastes containing fly ash and slag were investigated in this work. The hydration heat release rate and cumulative heat release of each cementitious paste system at 20 ℃ and 60 ℃ were measured by an isothermal calorimeter. The characteristic parameters of each cementitious paste system hydration process were calculated and analyzed using the Knudsen equation and Krstulović-Dabić hydration kinetic model. Besides, the hydration mechanism was analyzed. It was obtained that the cement-fly ash (C-F) binary system is not effective in reducing the early reaction rate but its overall heat release is lower; while, the cement-slag (C-S) binary system is more effective in reducing the reaction rate but its overall heat release is higher, and the cement-fly ash-slag (C-F-S) ternary system has the advantages of both above binary systems. Probably, the C-F-S ternary system is more consistent with the heating characteristics of massive concrete structures, and it is more applicable. There are few studies on the hydration characteristics of C-F-S ternary systems from the perspective of hydration kinetic, and this work provides theoretical basis for the selection of cementitious paste systems for massive concrete structures.