Analytical model for the moisture absorption in capillary active building materials. (December 2017)

• Record Type: Journal Article
• Authors: Janetti, Michele Bianchi; Wagner, Peter
• Is Part Of: Building and environment. Volume 126(2017)
• Page Start: 98
• Page End: 106
• Publication Date: 2017-12
• Subjects: Capillary active materials -- Water uptake test -- Free boundary problem; Buildings -- Environmental engineering -- Periodicals; Building -- Research -- Periodicals; Constructions -- Technique de l'environnement -- Périodiques; Electronic journals; 696
• DOI: 10.1016/j.buildenv.2017.09.018
• Languages: English
• ISSNs: 0360-1323

Abstract

Abstract: Isothermal absorption of moisture in a semi-infinite porous body is described with a diffusion law as a free boundary problem in which the porous domain is divided into a nearly saturated and a nearly dry region. This problem is solved via an analytical approach by assuming the diffusivity as a step function of the volumetric water content. The analytical solution is then applied to modeling the behavior of two real building materials during a water uptake test. It is shown that the model is able to explain the absorption process adequately, and that a good agreement with the measured data is obtained. Finally, a novel method for the inverse determination of the diffusivity via water uptake tests is proposed. Highlights: An analytical model describing the moisture absorption in a capillary building material is proposed. A closed form equation relating the water uptake coefficient to the diffusivity is derived. A good agreement with the measured data and with a numerical solution is found. A novel method for the inverse determination of the diffusivity is proposed.