Modelling moisture distribution in wooden cladding board as a result of short-term single-sided water soaking

Virta, Jari; Koponen, Seppo; Absetz, Ilmari

doi:10.1016/j.buildenv.2005.06.007

Cited by 19 publications

(7 citation statements)

References 12 publications

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“…Along with density, the wetting rate of cell walls is an important parameter considering the time-dependent cupping behaviour of wood [41]. The cupping of wooden cladding boards has been reported to be an important factor limiting the service life of wooden facades [12] and reducing the dimensional instability is of high relevance when trying to reduce the life cycle costs of materials.…”

Section: Discussionmentioning

confidence: 99%

Sorption-Related Characteristics of Surface Charred Spruce Wood

et al. 2018

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Surface charring of wood is a one-sided thermal modification process that can be used to create a hydrophobic, durable surface to exterior claddings. Spruce (Picea abies L.) wood samples were charred with a hot plate and several time-temperature combinations while using simultaneous surface compression. Temperature profile, water sorption, cupping after water exposure and density profile were measured. Furthermore, changes in the microstructure and surface functional groups were investigated by scanning electron microscopy and photoacoustic FT-IR spectroscopy. Results show that surface charring notably improves the hydrophobicity measured by contact angle, water floating and dynamic vapour sorption. Increased holding time during charring reduced the sorption but at the same time increased the dimensional instability measured by cupping. The density profile showed a shifting density peak with more severe modification regimes, indicating a more porous surface. The PAS-FTIR showed increased aromaticity of the surface that was also present in the pyrolysis zone beneath the surface in samples modified with longer holding time. Higher modification temperature affected the sorption as well as cupping positively but it is possible similar results can be obtained with lower temperature and longer holding time.

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Section: Discussionmentioning

confidence: 99%

Sorption-Related Characteristics of Surface Charred Spruce Wood

et al. 2018

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“…Moisture transport can be described with the moisture gradient as the driving potential, a diffusion coefficient that governs the rate of transport in the material and a mass transfer coefficient that governs the interaction with the air. This type of model has predominantly been used for modelling moisture transfer in the hygroscopic moisture range but has also been used to model free water flux (see Derbyshire and Robson 1999;De Meijer and Militz 2000;Virta et al 2006;Niklewski et al 2016). Liquid moisture transport is driven by capillary pressure differentials ; however, it is frequently described by the moisture gradient as the driving potential by utilizing the relationship between capillary pressure and degree of saturation (Spolek and Plumb 1981).…”

Section: Introductionmentioning

confidence: 99%

“…Liquid moisture transport is driven by capillary pressure differentials ; however, it is frequently described by the moisture gradient as the driving potential by utilizing the relationship between capillary pressure and degree of saturation (Spolek and Plumb 1981). The transport coefficient can then be described as a function of the intrinsic permeability of the material (see Virta et al 2006). Alternatively, the transport coefficient can be calculated from the moisture gradients under non-steady state conditions (Koponen 1984;Kang et al 2009).…”

Section: Introductionmentioning

confidence: 99%

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The effects of joints on the moisture behaviour of rain exposed wood: a numerical study with experimental validation

Niklewski

Fredriksson

2019

Wood Material Science & Engineering

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Joints in timber structures are particularly vulnerable to degradation due to their tendency to trap moisture. The mechanisms involved, and their effect on the moisture conditions of wood, are here investigated numerically. The horizontal member of a rail and post-type configuration is modelled numerically by a two-dimensional diffusion model with material properties for Norway spruce. Contact areas are assumed to be fully wetted when the specimen is exposed to free water but are unable to interact with the ambient air. Water that is absorbed through such areas cannot dry out through the same surface and is instead redistributed. The model was validated against experimental data, both previously unpublished data and data obtained from the literature, including both laboratory and outdoor exposure. The numerical solutions were, in general, consistent with the measured data. The model provides a simple, yet accurate, method to estimate the moisture conditions in certain types of wood joints. In addition, the spatial distribution of time spent above 25% moisture content was calculated, in order to investigate the suitability of the model for durability applications. ARTICLE HISTORY

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“…Apart from this, interconnecting pits provide one of the main pathways for the flow of liquid between cells, and their structure and distribution affects the penetration of liquid in wood [3]. Also, the air that is compressed during liquid penetration lowers the permeability of wood [4]. For this [5], reported that air is compressed during water soaking and additional counter pressure is formed that substantially reduces permeability.…”

Section: Introductionmentioning

confidence: 99%

Water Absorption Properties of Some Tropical Timber Species

Okoh¹

2014

JENR

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The water absorption characteristics during soaking of Terminalia superba (Ofram), Terminalia ivorensis (Emere) as currently threatened timber species and Quassia undulata (Hotrohotro) and Recinodendron heudelotii.(Wama) as lesser used timber species were studied to determine and compare their absorption and diffusion coefficients as potential substitutes for utilization. Water soaking was carried out for nineteen days and the data were fitted into the Fick's model to determine both the water absorption and diffusion coefficients. The study showed that, the mean values of the water absorption coefficient at initial stages of moisture sorption for Hortrohotro, Ofram, Emere and Wama were 3.51x 10-3 , 4.31x10-3 , 1.67x10-3 and 8.27x10-4 (kg/m 2 /s) respectively. The corresponding mean values of this parameter for the entire soaking process were also determined for the timber species viz; Ofram (2.91x 10-3), Hortrohotro (2.58x 10-3), Emere (1.14x 10-3) and Wama (6.11x 10-4) kg/m 2 s respectively. The measured diffusion coefficient for Wama, Emere, Ofram and Hotrohotro timber species were 9.637x10,-4 6.694x10-3 4.185x10-2 and 2.899x10-2 kg/m 2 /s respectively. Emere and Wama had lower absorption and diffusion characteristics than Hortrohotro and Ofram. Based on this study, Wama could be substituted for Emere and Hortrohotro with Ofram.

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Modelling moisture distribution in wooden cladding board as a result of short-term single-sided water soaking

Cited by 19 publications

References 12 publications

Sorption-Related Characteristics of Surface Charred Spruce Wood

Sorption-Related Characteristics of Surface Charred Spruce Wood

The effects of joints on the moisture behaviour of rain exposed wood: a numerical study with experimental validation

Water Absorption Properties of Some Tropical Timber Species

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