Investigation of the microstructural evolution of calcium sulfoaluminate cements by thermoporometry

Thermoporometry was applied to the investigation of the microstructural evolution of cementing systems. A pure calcium sulfoaluminate cement – CSA – and one mixed CSA–Portland system, together with a reference Portland cement were considered. Specimen preparation was carefully optimized in order to minimize any structural damage and the repeatability of results was checked through the utilization of inorganic standard. Nitrogen adsorption/desorption was used for comparison.A wide set of information could be acquired regarding the microstructure of the investigated materials: a) both the CSA and the mixed CSA–Portland system mainly revealed ink-bottle pores; b) a much more rapid development of hydrated structures was observed for all CSA cements than for the Portland cement; c) melting and freezing curves allow to gain information about the pore size distribution and the presence of pore entries of preferential size, about tortuosity and connectivity of the cement microstructure, and about the existence of isolated pores.