A first complementary observation was to study the kinetics of water binding over 28 days, through TGA, after hydration stoppage (Figure ). The amount of bound water seemed indeed to follow the trends observed on strength as highlighted on Figure where strength is plotted as a function of bound water. Sodium hydroxide induced a very fast water binding in the first day, which subsequently increased slowly towards a final bound mass fraction of 0.16-0.17 while mechanical strength increased. Sodium carbonate produced a two-step water binding process, with a first plateau around 0.06 wt% H2O after 7 days with little to no mechanical strength, followed by sudden increase to 0.14 wt% H2O at 14 days, with no apparent evolution later. The similarity with the time evolution of the compressive strength is striking, and it seems that the first stage of water binding (1 st week of curing) did not produce any hardening. Sodium silicate induced a more gradual water binding rate than hydroxide in the first week, but eventually reached the same plateau of bound water mass fraction of around 0.16-0.17.