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Moisture behavior of weathered wood surfaces during cyclic wetting : measurements and modeling

Niklewski, J. LU ; Brischke, C.; Frühwald Hansson, E. LU and Meyer-Veltrup, L. (2018) In Wood Science and Technology 52(6). p.1431-1450
Abstract

The effects of weathering on the in-service moisture behavior of wood have received only limited attention so far, with much focus being on the effect of photodegradation on the hydrophobicity of the wood surface. The objective of the present study was to examine the effect of weathering surfaces on the overall moisture behavior of wood specimens exposed to short-term cyclic spraying, with special emphasis on the surface conditions involved. Specimens cut from eight different species including hardwoods and softwoods were weathered for 8 years and continuously monitored during a single-sided cyclic spraying together with a set of axially matched controls. After each spray cycle, the duration of surface wetness was evaluated by... (More)

The effects of weathering on the in-service moisture behavior of wood have received only limited attention so far, with much focus being on the effect of photodegradation on the hydrophobicity of the wood surface. The objective of the present study was to examine the effect of weathering surfaces on the overall moisture behavior of wood specimens exposed to short-term cyclic spraying, with special emphasis on the surface conditions involved. Specimens cut from eight different species including hardwoods and softwoods were weathered for 8 years and continuously monitored during a single-sided cyclic spraying together with a set of axially matched controls. After each spray cycle, the duration of surface wetness was evaluated by resistance moisture sensors as well as an optical approach (colorimetric) based on time-lapse images. The moisture content in the core was monitored simultaneously by use of resistance moisture sensors. The optical method correlated well with the electrical resistance measurements and provided a simple and practical measure of the areal distribution of the surface wetness. The results showed specimens with a weathered surface to sustain a wet surface for about twice the duration of their axially matched control. A considerable, albeit smaller, effect was also observed deeper in the core. By adapting the length of the wet period on the exposed boundary, the corresponding response at the core of the Norway spruce specimens was reproduced numerically.

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author
organization
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type
Contribution to journal
publication status
published
subject
in
Wood Science and Technology
volume
52
issue
6
pages
20 pages
publisher
Springer
external identifiers
  • scopus:85053406543
ISSN
0043-7719
DOI
10.1007/s00226-018-1044-8
language
English
LU publication?
yes
id
bd4cdec6-3637-4bc4-ba15-831e3df50425
date added to LUP
2018-10-24 14:37:47
date last changed
2019-02-20 11:33:20
@article{bd4cdec6-3637-4bc4-ba15-831e3df50425,
  abstract     = {<p>The effects of weathering on the in-service moisture behavior of wood have received only limited attention so far, with much focus being on the effect of photodegradation on the hydrophobicity of the wood surface. The objective of the present study was to examine the effect of weathering surfaces on the overall moisture behavior of wood specimens exposed to short-term cyclic spraying, with special emphasis on the surface conditions involved. Specimens cut from eight different species including hardwoods and softwoods were weathered for 8 years and continuously monitored during a single-sided cyclic spraying together with a set of axially matched controls. After each spray cycle, the duration of surface wetness was evaluated by resistance moisture sensors as well as an optical approach (colorimetric) based on time-lapse images. The moisture content in the core was monitored simultaneously by use of resistance moisture sensors. The optical method correlated well with the electrical resistance measurements and provided a simple and practical measure of the areal distribution of the surface wetness. The results showed specimens with a weathered surface to sustain a wet surface for about twice the duration of their axially matched control. A considerable, albeit smaller, effect was also observed deeper in the core. By adapting the length of the wet period on the exposed boundary, the corresponding response at the core of the Norway spruce specimens was reproduced numerically.</p>},
  author       = {Niklewski, J. and Brischke, C. and Frühwald Hansson, E. and Meyer-Veltrup, L.},
  issn         = {0043-7719},
  language     = {eng},
  number       = {6},
  pages        = {1431--1450},
  publisher    = {Springer},
  series       = {Wood Science and Technology},
  title        = {Moisture behavior of weathered wood surfaces during cyclic wetting : measurements and modeling},
  url          = {http://dx.doi.org/10.1007/s00226-018-1044-8},
  volume       = {52},
  year         = {2018},
}