Kinetic study on the hydration of supersulfated cements

This study focuses on the hydration kinetics of supersulfated cement (SSC). The hydration heat release characteristics are analyzed, and a kinetic model for hydration is established. Then, the hydration kinetic parameters, such as hydration mechanism constant N, reaction rate constant K, and reaction rate constant Ea, are discussed. The results show that increasing the temperature promotes the nucleation of hydration products, thereby leading to the early attenuation of SSC hydration. Meanwhile, the water-to-cement ratio has little effect on the hydration process. A new hydration kinetic model considering the time-varying nature of hydration is proposed. In this model, SSC hydration after the induction period is primarily controlled by diffusion rather than by the nucleation of hydration products. The hydration process of SSC consists of a finite number of hydration cycles, and the ettringite (AFt) crystallization pressure is responsible for overcoming the "coating effect" to allow a new hydration cycle to begin. Hence, weakening the "coating effect" and increasing the AFt crystallization pressure are promising strategies to improve the degree of slag hydration. Finally, the activation energy of SSC is higher than that of cement.