A simple water sorption/retention (WS/WR) test, followed by stepwise static heating, was applied to the study of cement quality and the reactivity of its grain surface.
The physically bound water and hence the specific surface both in the unhydrated and in the hydrated state were estimated
as a function of the hydration time. Rehydration after heating at 220°C and contact with air was different inWS from that inWR samples, which indicates a difference in microstructure. XRD proved the formation of portlandite during the sorption test
and eventual heating at 200°C, and its transformation into carbonates on contact with air, especially on heating at 400°C.
The contents of these compounds were estimated from the mass difference between 400 and 800°C, which was compatible with the
mass change between 220 and 400°C and this indicates surface reactivity. The test may serve for the routine study of cement.