Water transport parameters of autoclaved aerated concrete: Experimental assessment of different modeling approaches

Abstract

The water-permeability, moisture-diffusivity, and sorptivity concepts of modeling liquid water transport in porous building materials are analyzed. An overall assessment of the particular models is performed using the moisture profiles measured for two types of autoclaved aerated concrete. The water-permeability and moisture-diffusivity modeling approaches are found suitable from a point of view of accuracy of moisture-transport simulation but they have certain limitations. While the water-permeability concept is advisable for compact materials, the moisture-diffusivity concept should be preferred for materials with a high water penetration rate. Therefore, a combination of both these approaches in a single laboratory is beneficial. The sorptivity concept, on the other hand, can be recommended for a basic assessment of water transport capabilities of building materials only.

Coupled Water and Salt Transport in Porous Materials: Rapid Determination of a Varying Diffusion Coefficient from Experimental Data

“…This formulation is appropriate in building physics, food science, and chemistry (Korecký et al 2014). From the viewpoint of non-equilibrium thermodynamics (Groot and Mazur 1984), it is equivalent to the formulation via the water permeability, K , or hydraulic conductivity, k, frequently employed in soil science, where the driving force is associated with the capillary water pressure, p, and hydraulic head, H , respectively.…”

“…From the viewpoint of non-equilibrium thermodynamics (Groot and Mazur 1984), it is equivalent to the formulation via the water permeability, K , or hydraulic conductivity, k, frequently employed in soil science, where the driving force is associated with the capillary water pressure, p, and hydraulic head, H , respectively. Indeed, one has κ = (K /η w )(∂ p/∂w) = k(∂ H/∂w), where η w is the dynamic viscosity of water and the derivatives can be obtained from the water retention curves H (w) (Philip and Vries 1957;Korecký et al 2014). Note that the diffusion-advection model (1) describes the coupled water and salt transport by a system of two coupled partial differential equations with two material parameters, κ and D, and three input quantities, w, C f , and C b .…”

Analysis of Porous Structure in Autoclaved Materials Modified by Glass Sand

“…When discussing the porosity of materials, it is important to consider how they are formed and the substrates and grain size of the components that form the basis of the various construction products. The number of macro-and micropores in the material is important in terms of the thermal properties of the materials, but also due to the strength properties and durability of these materials (the possibility of water penetration and migration in porous voids) [4].…”

Transições entre estados de hidratação em nanossilicatos sintéticos

“…This approach is classic in studies of moisture transport through porous materials 41,44 . In addition to the diffusion of H2O molecules in gas phase through mesopores, the active transport mechanisms can involve surface diffusion, associated with H2O adsorbed on the surface of pore walls, or possibly the formation of H2O micro-droplets due to 15 condensation of vapor in parts of the system 27,28 .…”

“…Partículas de argila esmectíta raramente são encontradas na natureza sem a presença de água. Isso significa que, se elas são usadas para a captura de CO2 [20,43,44], armazenamento de resíduos nucleares [45], remoção de metais pesados [28] ou para liberação de drogas [46], suas interações com água devem ser consideradas.…”