ABSTRACT
A moisture profile during the water imbibition process is characterised by two parameters connected with a pore structure of the tested material - the critical pore volumes, needed for a connected capillary pores network to be formed through the material, enabling water flow and air outflow: the critical moisture content and the volume of entrapped air. These critical pore volumes have been analysed for a set of capillary-porous composite silicate-based building materials with respect to their pore structure parameters.
It has been found out that the critical pore volumes for the air transport correspond with the volumes of pores with radii higher than ca 1000 nm (1 μ), i.e. the pores in which the entrapped air is not compressed due to capillary pressure in such an extent as in the smaller pores. The approximation of the absorption coefficient by the equivalent capillary model enables the estimation of critical moisture contents from measured data.
