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Determination of the moisture capacity of porous building materials

Carmeliet, J. and Roels, S.
2002
Journal of Thermal Envelope and Building Science, 25(03)

Carmeliet, J. and Roels, S., (2002), "Determination of the moisture capacity of porous building materials", Journal of Thermal Envelope and Building Science, 25(03).
Abstract:
The moisture capacity, which is required to solve the isothermal moisture transport equation, is generally expressed by parametric functions covering both the hygroscopic and over-hygroscopic regime. The modality or number of analytical functions needed to describe the corresponding pore volume distribution is introduced as an important parameter for a proper description of the moisture capacity or capillary pressure curve. We used the Markov procedure to estimate the parameters. The method allows not only to evaluate the goodness of fit and the well-posedness of the parameter identification problem, but also to determine the optimal location of the experimental data in order to minimize the effect of errors on the estimated parameters. We found that the wetting capillary pressure curve, relevant for many building physics problems of hygroscopic capillary active materials, is preferentially described by bimodal functions or unimodal functions with sufficient flexibility towards the hygroscopic zone. The use of fixed values of relative humidity for determining the limit between hygroscopic and over-hygroscopic regime cannot be recommended as useful a priori information. This limiting moisture content is rather a fitting parameter and is found not to coincide with the knick point moisture content defining the transition from vapor to liquid permeability. The optimal location of the experimental data is highly dependent on the chosen functional model and on the considered material. The goodness of fit only slightly reduces when using a minimal number of optimal data points compared to an extended data set.

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Also see:

A numerical model for unsaturated flow in a fracture - porous matrix system, S. Roels, K. Vandersteen & J. Carmeliet , XIV International Conference on Computational Methods in Water Resources, June 23-28, 2002

Jan Carmeliet, Staf Roels, and Koen Van Den Abeele, Multiscale network approach for estimating the imbibition permeability of porous building materials showing air entrapment.

Mesoscopic modelling of unsaturated moisture transfer in heterogeneous limestone, S. Roels , J. Carmeliet , H. Hens, Computational civil and structural engineering December 2000

A mesh adaptive technique for the simulation of unsaturated moisture transfer in open porous materials, S. Roels , J. Carmeliet , H. Hens, Finite elements January 2001

Carmeliet, J., S. Roels, K. Vandersteen. Unsaturated liquid water transfer in heterogeneous, cracked and composite materials. Proceedings of the International Building Physics Conference, Eindhoven, September 18 - 21.

Carmeliet, J., S. Roels and K. Vandersteen, 2001. Unsaturated liquid water transfer in heterogeneous, cracked and composite materials. Proceedings of the International Building Physics Conference, Eindhoven, The Netherlands.

Vandersteen, K, J. Carmeliet and J. Feyen, 1999. A network modeling approach to derive unsaturated hydraulic properties of a rough-walled fracture. Proceeding of EurAgEng's IG on Soil and Water Int. Workshop on Modelling of transport processes in soils at various scales in space and time. Leuven, Belgium, 24-26 Nov.: 132-141.
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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 isothermal moisture transport properties of porous building materials
  8. Determination of the liquid water diffusivity from transient moisture transfer experiments
  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 isothermal moisture transport properties of porous building materials
  6. Determination of the liquid water diffusivity from transient moisture transfer experiments
  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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