Cupping of wooden cladding boards in cyclic conditions—A study of heat-treated and non-heat-treated boards

Virta, Jari

doi:10.1016/j.buildenv.2004.10.014

Cited by 10 publications

(9 citation statements)

References 3 publications

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“…Continuous weathering of wooden claddings results in cracking of the surface and dead knots falling off (Virta, 2005). Moreover, cascading water on the cladding surface penetrates at higher rates than spraying water.…”

Section: Introductionmentioning

confidence: 99%

Studies of wooden cladding materials degradation by spectroscopy

Gupta¹,

Jelle

Jostein

et al. 2011

Proceedings of the Institution of Civil Engineers - Constructio

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Claddings or façades are the outer part of building envelopes. In this study, wooden claddings are exposed to natural and accelerated weathering. The natural climate exposure was performed at a field test site located in Trondheim,Norway. Accelerated climate exposure was performed in the laboratory in an Atlas SC600 MHG solar simulator.Attenuated total reflectance -Fourier transform infrared (ATR-FTIR) spectroscopy was used to characterise surfaces.The objective was to assess degradation by use of FTIR and thereby see how this may be applied to evaluate the service life of wood. Four types of wooden materials were studied; three untreated and one treated with chromated copper arsenate. Surface concentrated cellulose and lignin are the primary wood components used to determine the quality and durability of wood during ageing. It was found that treatment with preservative chemicals and surface roughness has definitive impacts on cladding surfaces and change to the chemical properties of the materials during ageing. The acceleration factor deduced from the Arrhenius equation shows that an increase in temperature lowers the service life of cellulose at a higher rate than the other wood components.

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Section: Introductionmentioning

confidence: 99%

Studies of wooden cladding materials degradation by spectroscopy

Gupta¹,

Jelle

Jostein

et al. 2011

Proceedings of the Institution of Civil Engineers - Constructio

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“…The reduced water absorption is likely to be due to a reduction in the number of hydroxyl groups (-OH) in the celluloses and hemicelluloses as a result of high temperature treatment. Furthermore, the decreased accessibility of water molecules to cellulose hydroxyl groups due to the increase in cellulose crystallinity and cross-linking in lignin can also play an important role [40][41][42]. The water uptake of the 250/4 and 250/6 specimens after 72 h decreased by about 38% and 36%, respectively.…”

Section: Resultsmentioning

confidence: 99%

Effect of One-Sided Surface Charring of Beech Wood on Density Profile and Surface Wettability

et al. 2021

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One-sided surface charred European beech wood (Fagus sylvatica L.) was studied. Radial and tangential specimens of dimensions of 50 × 25 × 350 mm were one-sided surface charred at 200, 250, 300, 350, and 400 °C for various times using a contact heating system. Specimens of dimensions of 50 × 25 × 50 mm3 were prepared for treatment intensity analysis and its effect on surface wettability. Density profiles of the radial and tangential charred specimens were determined using X-ray densitography with a resolution of 0.05 mm. The wettability of the one-sided surface charred wood specimens was analyzed via contact angle, measured using the sessile drop method and determined over 10 to 150 s. The oven-dried specimens were partially submerged in water and water uptake was recorded after 2, 4, 6, 8, 10, 48, and 72 h according to EN-927-5. The surface density of the radial specimen groups charred at 200 °C for 6 min and 250 °C for 4 min decreased by about 4.5 to 8.2%. With increasingly severe charring, the surface density decreased by about 15.5 to 33.5%. A mild charring process produced a surface charred layer of approx. 2 mm, while higher temperatures and longer times affected the density up to 4–6 mm beneath the surface. Differences were found between the water uptake of the radial and tangential charred beech specimens. The most significant decrease of 56% in water uptake was recorded for the radial group prepared at 200 °C for 20 min after floating in water for 72 h. Water uptake in the radial groups modified at 250 °C for 4 and 6 min after 72 h decreased by 38% and 36%, respectively. The tangential groups did not show any statistically significant decrease. The average water uptake of the groups charred at 200 °C for 20 min, 350 °C for 2 min and 400 °C for 1 min was greater than that of the reference; the variability of the measured data was significantly greater due to the highly anisotropic character of the tangential specimens. Micro cracks were also visible on the surface. Concluding from the results of this study, one-sided surface charred beech wood exhibits increased potential in terms of wood–water related properties when a temperature range of 200–400 °C is applied.

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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. Fast wetting of the surface in contrast to the interior creates tensions that either lead to checking or compressive strains.…”

Section: Discussionmentioning

confidence: 99%

“…Set-recovery of densified wood can be minimized by using saturated steam [36] and it is possible that post-conditioning of also charred wood could affect the extent of cupping. It is also worth noting that longer holding time leads to thicker pyrolysis zone beneath the charred surface, which behaves like TM wood with restricted sorption that in some conditions is also shown to cup less [12].…”

Section: Discussionmentioning

confidence: 99%

“…Regardless of the process used, TM wood exhibits low physical strength that prevents its use in load-bearing structures [3,9,10]. The colour will fade to grey in outdoors exposure, cracking and cupping takes place and maintenance interval (recoating) cannot be significantly increased compared to unmodified wood [11,12,13,14]. The modification methods also tend to be quite time-consuming [15,16] adding to the cost of the product.…”

Section: Introductionmentioning

confidence: 99%

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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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Cupping of wooden cladding boards in cyclic conditions—A study of heat-treated and non-heat-treated boards

Cited by 10 publications

References 3 publications

Studies of wooden cladding materials degradation by spectroscopy

Studies of wooden cladding materials degradation by spectroscopy

Effect of One-Sided Surface Charring of Beech Wood on Density Profile and Surface Wettability

Sorption-Related Characteristics of Surface Charred Spruce Wood

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