Evaluation of Functional Approaches to Describe the Moisture Diffusivity of Building Materials

    Published: Jan 2007

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    With a set of material parameters and a material model called engineering model of hygrothermal material characteristics, both proposed in (Scheffler, 2004), the material functions used for input to hygrothermal building component simulation programs can be adjusted. Using inverse identification of functional parameters by simulation of laboratory experiments, the model is calibrated to reproduce measured water uptake and drying curves. The developed material functions contain an approach to describe the liquid water conductivity of building materials. In addition, moisture storage data approximated by a GAUSSian functional approach, showing sufficient flexibility in the whole moisture range, is available. There with the derivative of the moisture retention curve is known at high precision and the liquid water diffusivity can be derived, too. There exists a wide interest in applicable material functions based on literature data. But literature reviews of hygrothermal material parameters often yield incomplete datasets and experimentally determined curves are lacking or are available at lower accuracy only. Different authors introduced several diffusivity approaches requiring less input parameters for description of liquid water transport in building materials. These models are evaluated by means of diffusivity data derived from the calibrated liquid water conductivity function of the engineering model. A selection of four accurately measured materials is used for this investigation. The investigation is based on controlled laboratory data of high resolution. With the knowledge gained from this study, the uncertainties in interpretation of incomplete datasets frequently encountered in literature reviews shall be reduced.


    diffusivity, hygrothermal material characteristics, moisture storage, moisture retention curve, liquid water conductivity, liquid water diffusivity, material functions, functional approach

    Author Information:

    Scheffler, Gregor
    Ph.D. Student and Head of Laboratory, Institute of Building Climatology, Dresden University of Technology, Dresden,

    Grunewald, John
    Adjunct Associated Professor, Syracuse University, Syracuse, NY

    Plagge, Rudolf
    Ph.D. Student and Head of Laboratory, Institute of Building Climatology, Dresden University of Technology, Dresden,

    Committee/Subcommittee: C16.30

    DOI: 10.1520/STP45405S

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