Moisture transport, thermodynamics, and boundary conditions in porous materials in presence of mechanical stresses

Effects of hydrophobic treatment on thermophysical properties of lightweight mortars

“…It is made up by two recipients (1) interconnected (3) and filled with distilled water. Some high absorbent felt layers (2) are placed on a digital balance (5) and immerged in the water recipients.…”

“…Water arising from different origins may interact with materials as mortars, plasters, stones, etc., so causing their deterioration (detectable through exfoliation, scaling, crumbling, etc. [1][2][3][4][5]). …”

On boundary condition in tunnels under partial saturation

“…Each of them is using a mass transfer coefficient which can be expressed as a function of the degree of saturation, the porosity or the air windspeed in the gallery [Dracos, 1980;Anagnostou, 1995;Zhongxhuan et al, 2004]. To obtain the evaporation flow, this mass transfer coefficient can be multiplied by the difference of relative humidity [Anagnostou, 1995], vapour pressure [Zhongxhuan et al, 2004] or vapour potential [Kowalski, 1997] between air gallery and the geological formation. As proposed by Ben Nasrallah & Pere [1998], we choose to express vapour exchanges as the difference of volumetric vapour mass between the tunnel atmosphere and rock mass:…”

“…Vapour exchanges occur when the relative humidities of air gallery and rock mass are different. Several formulations of the vapour flows can be found in the literature, which usually assume that the flow is proportional to the difference of relative humidity [Anagnostou, 1995], vapour pressure [Zhongxhuan et al, 2004], the vapour potential [Kowalski, 1997] or the volumetric vapour mass [Ben Nasrallah & Pere, 1998]. …”

A model for regular desiccation cracks formation

“…Many studies on shrinkage have been carried out [4][5][6][7][8]13,15,16,18,20,22], on the moisture transport [1][2][3]21], on thermodynamics [17], and on the dissolution around a fracture channel [19], but it is often difficult with these results to calculate in a specific morpheme, produced after cracking, all the thermodynamic parameters such as entropy, enthalpy, chemical potential, etc., involved in this process. The entropy change is related to two contributions: one is the external heat flow and the other is generated by the internal transformations associated with the internal energy variation.…”