THERMODYNAMIC AND KINETIC APPROACH TO THE ALKALI-SILICA REACTION .1. CONCEPTS

The reactivity of silica can be approached by using the thermodynamic concept of affinity and the kinetic concepts of reaction rate, energy of activation, and order with respect to OH-. The kinetics of dissolution of a given variety of silica must be studied on agitated systems ensuring the homogeneity of the solution at all times. This makes possible determination of the energy of activation and of the order with respect to OH-. On the other hand, the reduction in alkalinity has no meaning unless it is determined on static systems not including any supernatant.