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Determination of the isothermal moisture transport properties of porous building materials

Carmeliet, J., Roels, S.
2001
Journal of Thermal Envelope and Building Science, Vol. 24, No. 3, 183-210

Carmeliet, J., Roels, S., (2001), "Determination of the isothermal moisture transport properties of porous building materials", Journal of Thermal Envelope and Building Science, Vol. 24, No. 3, 183-210.
Abstract:
A multiscale network approach is proposed as a practical method for estimating the isothermal permeability of porous building materials covering hygroscopic and over hygroscopic ranges. The multiscale approach is based on the concept of examining the porous space at different levels of magnification, and it allows modeling of combined liquid water and water vapor transfer over a wide saturation range. The proposed method simply requires the knowledge of common moisture properties, such as the capillary pressure curve, the capillary absorption coefficient and water vapor permeability, which can be determined from standard experiments. Hysteresis between drainage and wetting due to air entrapment can be adequately modeled by considering only those pores that become filled by water. The calculated network permeability is validated comparing experimental and simulation results of isothermal capillary absorption and drying processes in ceramic brick and calcium silicate. It is shown that transient moisture processes of capillary absorption from a dry sample and the isothermal drying from an initially capillary saturated sample can be accurately modeled by a single nonlinear permeability and capillary pressure curve. The capillary pressure curve to be used is the main wetting curve, which describes the moisture content relationship from the dry state to the capillary moisture content, correctly taking into account air entrapment phenomena. The description of the absorption or drying moisture processes by a single or a double exponential diffusivity relation was found to be less accurate.
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Author Information and Other Publications Notes
Carmeliet, J.
Department of Civil Engineering Laboratory of Building Physics, Catholic University of Leuven, Belgium
  1. A comparison of different techniques to quantify moisture content profiles in porous building materials
  2. A multiscale network model for simulating moisture transfer properties of porous media
  3. A review of wind-driven rain research in building science
  4. A simplified numerical model for rainwater runoff on building facades: Possibilities and limitations
  5. Conservative modelling of the moisture and heat transfer in building components under atmospheric excitation
  6. Description of the moisture capacity of building materials
  7. Determination of the liquid water diffusivity from transient moisture transfer experiments
  8. Determination of the moisture capacity of porous building materials
  9. Driving rain on building envelopes II: representative experimental data for driving rain estimation
  10. Microscopic analysis of imbibition processes in oolitic limestone
  11. Modeling fluid flow in fractured media using continuum, network and discrete aproaches
  12. Pedestrian wind environment around buildings: literature review and practical examples
  13. Performance prediction for masonry walls with EIFS using calculation procedures and laboratory testing
  14. Position paper on material characterization and HAM model benchmarking
  15. Rainwater runoff from building facades: A review
  16. Simulating non-isothermal water vapour transfer: an experimental validation on multi-layered building components
  17. Spatial and temporal distribution of driving rain on a low-rise building
  18. The influence of soil moisture in the unsaturated zone on the heat loss from buildings via the ground
  19. Wind, rain and the building envelope: studies at the Laboratory of Building Physics, KULeuven
  20. Wind-driven rain as a boundary condition for HAM simulations: Analysis of simplified modelling approaches  
Roels, S.
Department of Civil Engineering Laboratory of Building Physics Catholic University of Leuven, Belgium
  1. A comparison of different techniques to quantify moisture content profiles in porous building materials
  2. A comparison of the Nordtest and Japanese test methods for the moisture buffering performance of building materials
  3. A quasi-steady state implementation of air convection in a transient heat and moisture building component model
  4. Description of the moisture capacity of building materials
  5. Determination of the liquid water diffusivity from transient moisture transfer experiments
  6. Determination of the moisture capacity of porous building materials
  7. Impact, absorption and evaporation of raindrops on building facades
  8. In situ determination of the moisture buffer potential of room enclosures
  9. Microscopic analysis of imbibition processes in oolitic limestone
  10. Modeling fluid flow in fractured media using continuum, network and discrete aproaches
  11. Position paper on material characterization and HAM model benchmarking
  12. Qualitative and quantitative assessment of interior moisture buffering by enclosures
  13. Review of mould prediction models and their influence on mould risk evaluation
  14. Simulating non-isothermal water vapour transfer: an experimental validation on multi-layered building components
  15. Wind-driven rain as a boundary condition for HAM simulations: Analysis of simplified modelling approaches  


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