Compréhension des mécanismes de transferts d'eau dans le bois

Abstract : Wood has excellent physical properties which however depend closely on the moisture content in the material. Because of its multi-scale structure and different states of water existing in the material, the mechanisms of water transfers in wood are still poorly understood. The essential phenomena at the origin of imbibition/drying properties of hardwood are studied in this thesis. We first show with classical macroscopic measurements that, water imbibition in wood is significantly damped compared to Washburn’s law which predicts the dynamic of capillary imbibition in the porous medium. The bound water and free water distributions obtained by MRI during imbibition show that, the bound water adsorbed in cell walls diffuses more quickly than the free water located in the pores. Free water cannot penetrate in the pores unless the cell walls have been saturated with bound water. The tomographic image analysis reveals that the damped dynamic of liquid water penetration in wood is due to the modification of wetting conditions by bound water content in the cell walls. Imbibition Tests with a hydrogel-based “artificial wood” confirm our hypothesis. Finally, the observations of wood drying by MRI show also different drying dynamics for bound and free water. At high moisture content, wood drying is controlled by the evaporation of free water from a dry front. Bound water starts to evaporate significantly only after the total disappearance of free water
Complete list of metadatas

Cited literature [59 references]  Display  Hide  Download

https://pastel.archives-ouvertes.fr/tel-02084019
Contributor : Abes Star <>
Submitted on : Friday, March 29, 2019 - 12:41:58 PM
Last modification on : Monday, April 8, 2019 - 2:39:25 PM
Long-term archiving on : Sunday, June 30, 2019 - 2:32:16 PM

File

TH2018PESC1044.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-02084019, version 1

Collections

Citation

Meng Zhou. Compréhension des mécanismes de transferts d'eau dans le bois. Matériaux composites et construction. Université Paris-Est, 2018. Français. ⟨NNT : 2018PESC1044⟩. ⟨tel-02084019⟩

Share

Metrics

Record views

161

Files downloads

101