Reaction kinetics of CaO in the presence of silicate ions and influence of stirring

Abstract The reaction of CaO with water is important for many applications. In the present study, the impact of silicate ions having a concentration between 3 and 100 mM on the reaction rate of CaO in suspension (l/s =6) is investigated by isothermal conduction calorimetry, inductively coupled plasma-optical emission spectroscopy and scanning electron microscopy. Results report a very strong impact of silicate ions on the hydration kinetics of CaO with a significant retardation and decrease of reaction rate associated with the appearance of an induction period. The slowing down and delay of the hydration are highly affected by the stirring duration. It is discussed, if a temporary stabilization of the portlandite layer on CaO surface by C-S-H is responsible for the observed effects. The findings of this study are discussed in the context of metal/alloy and glass corrosion and the hydration of Portland cement.