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Durability of Mass Timber Structures: a Review of the Biological Risks

https://research.thinkwood.com/en/permalink/catalogue1838
Year of Publication
2018
Topic
Environmental Impact
Serviceability
Material
CLT (Cross-Laminated Timber)
Author
Wang, Jasmine
Stirling, Rod
Morris, Paul
Taylor, Adam
Lloyd, Jeff
Kirker, Grant
Lebow, Stan
Mankowski, Mark
Organization
Forest Products Laboratory
Year of Publication
2018
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Environmental Impact
Serviceability
Keywords
High-Rise
Durability
Biodegradation
Wood Protection
Research Status
Complete
Series
Wood and Fiber Science
Summary
Mass timber structures have the potential to change wooden construction on a global scale. Numerous mass timber high-rise buildings are in planning, under development or already built and their performance will alter how architects and engineers view wood as a material. To date, the discussion of material durability and biodegradation in these structures has been limited. While all materials can be degraded by wetting, the potential for biodegradation of wood in a mass timber building requires special consideration. Identifying and eliminating the conditions that might lead to this degradation will be critical for ensuring proper performance of wood in these structures. This article reviews and contrasts potential sources of biodegradation that exist for traditional wood construction with those in mass timber construction and identifies methods for limiting the degradation risk. Finally, future research needs are outlined.
Online Access
Free
Resource Link
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Evaluation of the Block Shear Resistance of Glulam Manufactured from Borate-Treated Lamina Wthout Planing After Treatment

https://research.thinkwood.com/en/permalink/catalogue367
Year of Publication
2015
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Bridges and Spans
Author
Stirling, Rod
Feng, Martin
Morris, Paul
Organization
FPInnovations
Year of Publication
2015
Format
Report
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Bridges and Spans
Topic
Mechanical Properties
Keywords
Preservative
Borate
Canada
Shear Resistance
Polyurethane
Research Status
Complete
Summary
Effective preservative treatments for Canadian glulam products are needed to maintain markets for mass timber on building facades, access markets with significant termite hazards, and expand markets for wood bridges. For all three applications, borate-treatment of lamina before gluing would be preferred as it would lead to maximum preservative penetration. However, the need to plane after treatment and prior to gluing removes the best-treated part of the wood, and creates a disposal issue for treated planer shavings. The present research evaluates the block shear resistance of glulam prepared from untreated and borate-treated lamina with a polyurethane adhesive. Borate treatment was associated with a small but statistically significant loss in median shear strength when evaluated dry; however, there was no difference between the performance of untreated and borate-treated samples when exposed to the vacuum-pressure soak/dry or the boil-dry-freeze/dry procedures. Further work is needed to modify the composition or application of the resin to improve shear strength for glulam applications and ensure consistent performance. However, overall, these data indicate that samples prepared from borate-treated lamina perform similarly in terms of block shear resistance to those prepared from untreated lamina.
Online Access
Free
Resource Link
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Treatability of Cross Laminated Timber With a Low Moisture Uptake Surface-Applied Penetrating Process for Applying Termiticides

https://research.thinkwood.com/en/permalink/catalogue2642
Year of Publication
2014
Topic
Serviceability
Material
CLT (Cross-Laminated Timber)
Author
Stirling, Rod
Morris, Paul
Organization
FPInnovations
Year of Publication
2014
Format
Report
Material
CLT (Cross-Laminated Timber)
Topic
Serviceability
Keywords
Termites
Preservative Treatment
Panels
Hem-Fir
Research Status
Complete
Summary
Cross-laminated timber (CLT) may require preservative treatment in markets with severe termite hazards. Given the size of CLT panels, conventional pressure treatment would not be feasible. We therefore assessed the treatability of CLT panels with an alternative low moisture uptake surface-applied penetrating process for applying termiticides. Hem-fir panels were selected for the initial tests on the grounds that western hemlock and amabilis fir are relatively treatable. Nine test panels were dip treated and stored for 7, 14, or 21 day activation periods. Borate retention ranged from 1.2 to 6.5 kg/m3 and penetration ranged from 3 to 9 mm. Longer activation periods did not result in improved penetration. Greater penetration would likely be needed to meet performance-based standards.
Online Access
Free
Resource Link
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