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Materials and Structures

, Volume 36, Issue 7, pp 448–452 | Cite as

Drying of porous building materials: hydraulic diffusivity and front propagation

  • D. A. Lockington
  • J. -Y. Parlange
  • D. A. Barry
  • C. A. Leech
Article

Abstract

One-dimensional drying of a porous building material is modelled as a nonlinear diffusion process. The most difficult case of strong surface drying when an internal drying front is created is treated in particular. Simple analytical formulae for the drying front and moisture profiles during second stage drying are obtained when the hydraulic diffusivity is known. The analysis demonstrates the origin of the constant drying front speed observed elsewhere experimentally. Application of the formulae is illustrated for an exponential diffusivity and applied to the drying of a fired clay brick.

Keywords

Front Propagation Front Position Moisture Profile Hydraulic Diffusivity Front Speed 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Résumé

Le séchage d'un matériau poreux est décrit par l'équation de diffusion non linéaire. Pour un coefficient de diffusion donné, des formules analytiques simples sont obtenues pour les profils hydriques et pour le front de séchage. Le cas, difficile à traiter, où la surface du matériau est éventuellement sèche, est considéré en détail. L'analyse montre l'origine de la vitesse constante du front de séchage, qui a été observée dans des études expérimentales indépendantes. L'application des formules au séchage d'une brique d'argile est illustrée pour un coefficient de diffusion qui dépend exponentiellement du contenu hydrique.

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References

  1. [1]
    Pel, L., ‘Moisture transport in porous building materials’, Ph. D. Thesis, Eindhoven University of Technology, The Netherlands (1995).Google Scholar
  2. [2]
    Pel, L., Brocken, H. and Kopinga, K. ‘Determination of moisture diffusivity in porous media using moisture concentration profiles’,Int. J. Heat and Mass Transfer 39 (1996) 1273–1280.CrossRefGoogle Scholar
  3. [3]
    Crank, J., ‘The Mathematics of Diffusion’, (Clarendon Press, Oxford, 1975.zbMATHGoogle Scholar
  4. [4]
    Crausse, P., Laurent, J.P. et Perrin, B., ‘Influence des phénomènes d'hystérésis sur les propriétés hydriques de matériaux poreux: comparaison de deux modèles de simulation du comportement thermohydrique de parois de bâtiment’,Revue Générale de Thermique 35 (1996) 95–106.CrossRefGoogle Scholar
  5. [5]
    Landman, K.A., Pel, L. and Kaasschieter, E.F., ‘Analytic modelling of drying of porous materials’,Mathematical Engineering in Industry 8 (2) (2001) 89–122.CrossRefGoogle Scholar
  6. [6]
    Pel, L., Landman, K.A. and Kaasschieter, E.F., ‘Analytic solution for the non-linear drying problem’,Int. J. Heat and Mass Transfer 45 (15) (2002) 3173–3180.CrossRefGoogle Scholar
  7. [7]
    Parslow, J., Lockington, D. and Parlange, J.-Y., ‘A new perturbation expansion for horizontal infiltration and sorptivity estimates’Transport in Porous Media 3 (1988) 133–144.CrossRefGoogle Scholar
  8. [8]
    Hall, C., ‘Barrier performance of concrete: a review of fluid transport theory’,Mater. Struct. 27 (1994) 291–306.CrossRefGoogle Scholar
  9. [9]
    Lockington, D.A., Parlange, J.-Y., and Dux, P.F., ‘Sorptivity and estimating water penetration in unsaturated concrete’,Mater. Struct. 32 (1999) 342–347.CrossRefGoogle Scholar

Copyright information

© RILEM 2003

Authors and Affiliations

  • D. A. Lockington
    • 1
  • J. -Y. Parlange
    • 2
  • D. A. Barry
    • 3
  • C. A. Leech
    • 1
  1. 1.Environmental EngineeringThe University of QueenslandBrisbaneAustralia
  2. 2.Department of Biological and Environmental EngineeringCornell UniversityIthacaUSA
  3. 3.School of Engineering and ElectronicsUniversity of EdinburghEdinburghUK

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