Coupled Heat And Moisture Transport In A Building Envelope On Cast Gypsum Basis
Free (open access)
J. Maděra, P. Tesárek & R. Černý
Flue gas desulphurization (FGD) gypsum can be potentially used as a material for load bearing structures. In this paper, a computational assessment of hygrothermal performance of a building envelope based on several modifications of FGD gypsum is presented. In the computer simulations of temperature and relative humidity fields, three variations of FGD gypsum wall, based on the raw material and on two types of hydrophobized gypsum, with the thickness of 300 mm, are solved. The thermal insulation function of the wall is achieved by exterior thermal insulation boards with the thickness of 100 mm, which are considered in four variants. Insulation I is hydrophilic material with a low value of hygroscopic moisture content on mineral wool basis, Insulation II capillary active material with higher value of hygroscopic moisture content on calciumsilicate basis, Insulation III hydrophobic material with a low value of water vapor resistance factor on mineral wool basis and Insulation IV hydrophobic material with higher value of water vapor resistance factor on polystyrene basis. Lime plaster with the thickness of 10 mm is used on the exterior wall surface. The computational analysis reveals that use of hydrophobization admixtures in the gypsum element does not lead to any improvement of hygrothermal behavior of the envelope provided by an exterior thermal insulation. Therefore, the application of a gypsum element without any hydrophobization seems to be a more favorable solution. The common hydrophobized thermal insulation materials on the basis of polystyrene or mineral wool are found to be satisfactory from the point of view of hygrothermal performance of the analyzed castgypsum based envelope. Keywords: building envelope, flue gas desulphurization (FGD) gypsum, thermal insulation boards, heat and moisture transport.
building envelope, flue gas desulphurization (FGD) gypsum, thermal insulation boards, heat and moisture transport.