Experimental characterisation of the isosteric desorption energy of VeRCoRs concrete: Comparison of the isotherms and hygrometric methods

The Clausius-Clapeyron equation is an effective tool for describing the effect of temperature on water vapour adsorption isotherms in cementitious materials. The key information is the isosteric energy. This can currently be characterised experimentally using two approaches: (1) the isotherms method, which involves experimentally acquiring the desorption isotherm for two (or more) different temperatures, and (2) the hygrometric method, which involves monitoring the increase in vapour pressure at equilibrium with a small sample subjected to increasing temperature steps. It turns out that although each method has a fairly high uncertainty, the results obtained are similar. Finally, the results seem to suggest that the isosteric energy of Portland-based cementitious materials could be considered unique.