2019/12/17 by Harmathy, T. Z.
#Béton #Concrete #Moisture performance #Performance hygrométrique #air moisture transfer #béton poreux #capillary - funicular states #capillary flow #convective transport #diffusion #evaporation - condensation #fresh concretes #heat transfer #hydratation #hydration #hydration reactions #moisture movement #pendular state #phase transformation #pore structure complexity #porous concrete #porous media #transfert de chaleur #transfert de l'humidité de l'air #transformation de phase
paper · doi:10.4224/40001743
Over the years three theories have gained general acceptance in explaining the movement of moisture in porous media: the diffusion theory, the capillary flow theory, and the evaporation-condensation theory. Because a wet porous solid actually consists of at least three phases, the mechanism of simultaneous moisture and heat transport is very complex. During the capillary and funicular states of the system, moisture moves primarily by a convective transport mechanism, and the rate of moisture movement is relatively insensitive to the properties of the solid matrix. In the pendular state, the evaporation-condensation mechanism is predominant, and the rate of moisture migration depends on the complexity of the pore structure. For fresh concretes the related problems are augmented by the hydration reactions.