Author(s)

Peter Schiller¹, Mirco Wahab¹, Thomas Bier², Sandra Waida², Hans-Jörg Mögel¹

¹Inst. Phys. Chem., TU-Bergakademie Freiberg, Freiberg, Germany.
²IKGB, TU-Bergakademie Freiberg, Freiberg, Germany.

Mesopores in porous solids can produce a pronounced sorption hysteresis at moderate and high reduced vapor pressures of the ambient gas that is condensed in the pores. Unlike to other conventional porous materials, cement pastes often behave exceptionally. The water sorption hysteresis frequently persists at very low humidity. This hysteresis is reflected in a corresponding hysteresis loop of the solid skeleton volume. We discuss a theoretical model based on the strong compression force exerted by a condensate on the walls of narrow slit pores embedded in an elastic solid. This compression force is shown to be capable of shifting walls of narrow slit pores. Humidity-dependent closing and reopening of slit pores can produce hysteresis loops even at low humidity.

Porous Solids, Sorption Hysteresis, Capillary Forces, Cement-Based Materials

Schiller, P. , Wahab, M. , Bier, T. , Waida, S. and Mögel, H. (2016) Sorption Hysteresis of Hardened Cement Pastes. Journal of Materials Science and Chemical Engineering, 4, 40-48. doi: 10.4236/msce.2016.42005.