Early hydration of alkali-activated slag: Developments in monitoring techniques

Developments in the application of electrical methods in the study of the early hydration reaction kinetics of alkali-activated slag are presented. Work focuses on monitoring the change in both conductance and capacitance over the initial 24-48 h hydration with electrical measurements taken over the frequency range 1-100 kHz. In the current study, sodium hydroxide and sodium silicate are used as activators. The work highlights the frequency dependence of capacitance and, to a lesser extent conductance: in addition, over the duration of the test, both these electrical parameters undergo significant changes which can be interpreted in terms of mechanisms of hydration. It is shown that electrical methods could be exploited as a convenient technique in characterizing the reactivity of these materials with alkaline activators.