Validation of hygrothermal material modelling under consideration of the hysteresis of moisture storage.

Abstract

The achievable accuracy of hygrothermal building component simulation is significantly dependent on the applied material functions. These functions are determined by the material modelling marking the connection between the basic storage and transport parameters which are obtained from basic measurements, and the storage and transport coefficients which are defined within the balance and flow equations. It is the aim of the present study to develop a flexible and widely applicable material model which is not restricted to the current level of the transport theory. Furthermore, limits and options of this model are to be validated by means of four building materials on the basis of special transient moisture profile measurements. By the presented study, the material modelling has been decisively further developed, the set of basic measurement methods has been extended by a substantial experiment and the instantaneous profile measurement technique has been made applicable to Building Physics. Moreover, the influences of the process history and the process dynamics on the moisture transport and the resulting moisture profiles could be shown and proven. By that, not only a material model is now available which perfectly applies to the requirements of flexibility, applicability and extendibility. The obtained data provides also a powerful basis for further research and development.

Effect of evaporation cooling on drying capillary active building materials

“…In accordance with results by other authors (e.g. [9] ), these parameters determine the slope of the water content trends (hence the magnitude of the drying rate) during the second, nearly isothermal, phase of drying. Considering that the convective heat transfer coefficient α c is the only input used for the model calibration, the described experiment can also be viewed as a method for inverse determination of this parameter.…”

“…The increasing interest in this field is proved by numerous recent studies concerning both modeling and experimental research (e.g. [1][2][3][4][5][6][7][8][9] ). This work aims at extending the current knowledge by investigating the drying behavior of calcium silicate, which is widely used as insulation material due to its favorable hygrothermal properties [2,3,10,11] .…”

Experimental characterization of moisture transport in brick masonry with natural hydraulic lime mortar

“…In the overhygroscopic or capillary range (95-100% RH), liquid transport by capillarity dominates the moisture transfer. A set of basic experiments and derived material properties for the characterization of a porous material over the entire moisture range was defined by Scheffler [11]. It includes general properties, such as bulk density and open porosity, moisture storage capacity, vapor diffusion properties, and liquid transport properties, such as liquid water diffusivity or permeability, which may be derived from water absorption experiments and drying tests.…”

“…Numerous works in the literature have documented the hygric properties of clay brick as a porous building material, e.g. [11][12][13]19]. However, given the high intrinsic variability previously mentioned, the extrapolation of literature data to specific real case scenarios is not always straightforward.…”

Untersuchungen zur Frostbeanspruchung geneigter Oberflächen aus hochfestem Spritzbeton

“…Die Modellierung erfolgte mit der Simulationssoftware Delphin (Version 6.1.0)[15]. Während die Schädigungsprozesse von Betonen infolge Frosteinwirkung auf der Verkettung einer Vielzahl von physikalischen Mechanismen beruhen, zielen diese hygro thermischen Simulationen auf die vergleichende Einordnung der Einwirkungsseite ab.In Vorbereitung erfolgte die Bestimmung von wesentlichen Materialparametern des Betons für die Anpassung des hygrischen Materialmodells nach[16]. Gemessen wurden dabei der Wasseraufnahmekoeffizient A w und der kapillare Wassergehalt nach ISO 15148[17], die Wasserdampfdiffusionswiderstandszahl m dry nach ISO 12572[18] sowie Stützpunkte der sorptiven Eigenschaften θ(ϕ) nach ISO 12571[19].Auf Basis der Messdaten wurde ein vergleichbarer Betondatensatz aus der Materialdatenbank von Delphin 6.1.0 ausgewählt und entsprechend modifiziert.…”