Monitoring Gypsum Plaster Setting in a Foam through Raman Spectroscopy

We use Raman spectroscopy to probe in situ the hydration reaction of a foamed mineral binder, here gypsum plaster. We show the strong effect of the mixing process used for foaming on the hydration kinet-ics. On the contrary, we observe no effect of the cationic surfactant tetradecyltrimethylammonium bromide (TTAB) used as foaming agent and of the foam structure. By tuning the hydration time scale with a setting retardant (citric acid) and measuring in parallel the characteristic bubble radius in the foam, we show that hydration kinetics control the arrest of the bubble-size evolution in the fresh foam and the final pore size in the set gypsum.