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What Is the Impact of Mass Timber Utilization on Climate and Forests?

https://research.thinkwood.com/en/permalink/catalogue2921
Year of Publication
2022
Topic
Environmental Impact
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Pasternack, Rachel
Wishnie, Mark
Clarke, Caitlin
Wang, Yangyang
Belair, Ethan
Marshall, Steve
Gu, Hongmei
Nepal, Prakash
NDolezal, Franz
Lomax, Guy
Johnston, Craig
Felmer, Gabriel
Morales-Vera, Rodrigo
Puettmann, Maureen
Huevel, Robyn
Organization
USDA Forest Service Forest Products Laboratory
University of Exeter
Universidad de Chile
Universidad Católica del Maule
Editor
Ganguly, Indroneil
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Environmental Impact
Keywords
Life-Cycle Assessment
Climate Change
Embodied Carbon
Carbon Storage
Research Status
Complete
Series
Sustainability
Summary
As the need to address climate change grows more urgent, policymakers, businesses, and others are seeking innovative approaches to remove carbon dioxide emissions from the atmosphere and decarbonize hard-to-abate sectors. Forests can play a role in reducing atmospheric carbon. However, there is disagreement over whether forests are most effective in reducing carbon emissions when left alone versus managed for sustainable harvesting and wood product production. Cross-laminated timber is at the forefront of the mass timber movement, which is enabling designers, engineers, and other stakeholders to build taller wood buildings. Several recent studies have shown that substituting mass timber for steel and concrete in mid-rise buildings can reduce the emissions associated with manufacturing, transporting, and installing building materials by 13%-26.5%. However, the prospect of increased utilization of wood products as a climate solution also raises questions about the impact of increased demand for wood on forest carbon stocks, on forest condition, and on the provision of the many other critical social and environmental benefits that healthy forests can provide. A holistic assessment of the total climate impact of forest product demand across product substitution, carbon storage in materials, current and future forest carbon stock, and forest area and condition is challenging, but it is important to understand the impact of increased mass timber utilization on forests and climate, and therefore also on which safeguards might be necessary to ensure positive outcomes. To thus assess the potential impacts, both positive and negative, of greater mass timber utilization on forests ecosystems and emissions associated with the built environment, The Nature Conservancy (TNC) initiated a global mass timber impact assessment (GMTIA), a five-part, highly collaborative research program focused on understanding the potential benefits and risks of increased demand for mass timber products on forests and identifying appropriate safeguards to ensure positive outcomes.
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Life Cycle Assessment of Cross-Laminated Timber Transportation from Three Origin Points

https://research.thinkwood.com/en/permalink/catalogue2923
Year of Publication
2022
Topic
Environmental Impact
Material
CLT (Cross-Laminated Timber)
Author
Hemmati, Mahboobeh
Messadi, Tahar
Gu, Hongmei
Organization
University of Arkansas
USDA Forest Service Forest Products Laboratory
Editor
D’Acierno, Luca
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Environmental Impact
Keywords
Life-Cycle Assessment
Mass Timber
Global Warming Potential
Transportation
Research Status
Complete
Series
Sustainability
Summary
Cross-laminated timber (CLT) used in the U.S. is mainly imported from abroad. In the existing literature, however, there are data on domestic transportation, but little understanding exists about the environmental impacts from the CLT import. Most studies use travel distances to the site based on domestic supply origins. The new Adohi Hall building at the University of Arkansas campus, Fayetteville, AR, presents the opportunity to address the multimodal transportation with overseas origin, and to use real data gathered from transporters and manufacturers. The comparison targets the environmental impacts of CLT from an overseas transportation route (Austria-Fayetteville, AR) to two other local transportation lines. The global warming potential (GWP) impact, from various transportation systems, constitutes the assessment metric. The findings demonstrate that transportation by water results in the least greenhouse gas (GHG) emission compared with freight transportation by rail and road. Transportation by rail is the second most efficient, and by road the least environmentally efficient. On the other hand, the comparison of the life cycle assessment (LCA) tools, SimaPro (Ecoinvent database) and Tally (GaBi database), used in this research, indicate a remarkable difference in GWP characterization impact factors per tonne.km (tkm), primarily due to the different database used by each software.
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Determination of seismic performance factors for cross-laminated timber shear walls based on FEMA P695 methodology

https://research.thinkwood.com/en/permalink/catalogue3215
Year of Publication
2022
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Lindt, John van de
Amini, M. Omar
Rammer, Douglas
Line, Philip
Pei, Shiling
Popovski, Marjan
Organization
Forest Products Laboratory
Year of Publication
2022
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Seismic
Keywords
Seismic Design
Mass Timber Design
FEMA P695
Research Status
Complete
Summary
Cross-laminated timber (CLT) construction has been gaining popularity in North America. However, CLT-based seismic force resisting systems are not recognized in current U.S. design codes, which is among the many challenges preventing widespread adoption of CLT in the United States. The purpose of this study was to investigate the seismic behavior of CLT-based shear wall systems and to determine seismic performance factors, namely, the response modification factor (R factor), the system overstrength factor(O), and the deflection amplification factor (Cd), using the FEMA P695 procedure. Nine index buildings including single-family dwellings, multifamily dwellings, and commercial (including mixed use) midrise buildings were developed, from which 72 archetypes were extracted. Testing performed at the component and subassembly levels included connector tests and isolated shear wall tests. A CLT shear wall design method was developed and used to design the archetypes, which were then assessed with nonlinear pushover analysis and incremental dynamic analysis. Based on the required collapse margin, an R factor of 3 is proposed for CLT shear wall systems with 2:1 or mixed aspect ratio panels up to 4:1, and an R factor of 4 is proposed for CLT shear wall systems made up of only 4:1 aspect ratio panels. Results from this study have been proposed for recognition in U.S. building codes (such as the International Building Code) through specific change proposals to update reference standards such as ASCE 7 Minimum Design Loads and Associated Criteria for Buildings and Other Structures and Special Design Provisions for Wind and Seismic.
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Evaluation of Modulus of Elasticity and Modulus of Rupture of Cross-Laminated Timber with Longitudinal Vibration NDE Techniques

https://research.thinkwood.com/en/permalink/catalogue3217
Year of Publication
2022
Topic
Acoustics and Vibration
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Correa, Laurice Mara Spinelli
Franca, Frederica Jose Nistal
Shmulsky, Rubin
Seale, R. Daniel
Ross, Robert
Senalik, Christopher Adam
Organization
Forest Products Laboratory
Year of Publication
2022
Format
Report
Material
CLT (Cross-Laminated Timber)
Topic
Acoustics and Vibration
Mechanical Properties
Keywords
MOE
MOR
SYP
Longitudinal Vibration
Time Domain
Frequency Domain
Strength Model
Research Status
Complete
Summary
This paper presents research conducted to examine the potential of using longitudinal vibration techniques to evaluate the modulus of elasticity and strength of cross-laminated timber (CLT). Thirty-nine CLT panels were manufactured from southern pine dimension lumber in accordance with accepted manufacturing standards. Nominal 2 by 8 in. southern pine lumber specimens were used for the three-ply panels. A 10-ft-long specimen, having a 4.125- by 18-in. cross-section, was obtained from each panel. Weight and dimensions were determined for each specimen, and longitudinal vibration nondestructive evaluation techniques were used to determine frequency of oscillation and energy loss characteristics of the specimens. The dynamic modulus of elasticity was then determined. Each specimen was then tested to failure in a flatwise (third point) bending mode. Flatwise bending modulus of elasticity and strength (modulus of rupture) were determined. Excellent correlative relationships were observed between dynamic and flatwise bending moduli. A strong positive relationship was observed between the dynamic modulus and flatwise bending strength. Nondestructive testing of CLT panels is recommended for quality control protocols.
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Moisture Monitoring of a CLT Structure in a Southern Climate

https://research.thinkwood.com/en/permalink/catalogue3218
Year of Publication
2022
Topic
Moisture
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Poblete, Elizabeth
Messadi, Tahar
Murray, Cameron
Zelinka, Samuel
Organization
University of Arkansas
Forest Products Laboratory
Publisher
ASCE
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Moisture
Keywords
Wood Moisture Relations
Building Health
Remote Sensing
Research Status
Complete
Series
Journal of Architectural Engineering Journal
Summary
Understanding moisture behavior in cross-laminated timber (CLT) is critical to the widespread use of CLT in construction in the United States. Currently, very little data exist on the long-term impact of moisture on CLT in real structures. The objective of this research was to collect data regarding the long-term moisture variation in the CLT panels at the University of Arkansas student residential building, named Adohi Hall. The climate of Northwest Arkansas is different from those of previously monitored buildings, mostly located in the Pacific Northwest. Comparatively, Northwest Arkansas has a warmer climate with higher average annual precipitation. Moisture sensors were installed in 45 locations throughout the building to provide a comprehensive evaluation of the building. Results indicate that for the interior floors of the building, i.e., not the roof, CLT panels have not encountered moisture intrusions. At the roof level, moisture intrusions during construction were trapped in the CLT panels by waterproofing. This trapped moisture resulted in slower drying to below acceptable levels of moisture.
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Post-layup protection of mass timber elements in above ground protected exposures: 2-year results

https://research.thinkwood.com/en/permalink/catalogue3234
Year of Publication
2022
Topic
Moisture
Material
CLT (Cross-Laminated Timber)
Author
Mankowski, Mark E.
Shelton, Thomas
Kirker, Grant T.
Morrell, Jeffrey J.
Organization
Forest Products Laboratory
University of the Sunshine Coast
Year of Publication
2022
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Moisture
Keywords
Mass Panel Plywood
AWPA Standard E21
Above Ground Testing
Soil Termiticide
Borate
Field Test
Durability
Decay
Termite
Conference
Proceedings IRG Annual Meeting (ISSN 2000-8953)
Research Status
Complete
Summary
Mass timber has seen increased use as a building material for low and mid-rise construction in recent decades. The durability of mass timber elements has not been fully examined and the effects of wood destroying organisms on this these materials merits attention. The effectiveness of currently labeled soil termiticides and passively applied biocides at post-construction or as remedial agents needs to be evaluated for mass timber used in structures, particularly in areas with elevated risk of termite attack. The ability of soil insecticidal drenches or spray-on insecticide/fungicide treatments for protecting mass timber in service was assessed with a modified AWPA Standard E21 above-ground test using three ply Douglas-fir or southern pine cross-laminated timber as well as Douglas-fir mass plywood panels. Samples of each material (305 x 102 x 102 mm) were installed in an above ground protected test at the Harrison Experimental Forest (HEF) (Saucier, Mississippi) in September, 2019. Six replicates of five treatments including soil termiticide, no treatment, spray-on borate at initiation, borate rods and remedial treatment, using spray on borate of attacked material after two years, were tested. Samples were left undisturbed for two years and then examined and rated. Near surface moisture content increased to levels approaching the fiber saturation point over the two-year non-disturbance period. Untreated control samples were attacked by both decay fungi and termites. Samples treated with borates at test initiation showed limited decay or termite attack. Soil termiticide treated plots showed no sign of termite attack, but some samples had heavy decay compared to non-soil termiticide treated plots.
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Assessment of Termite and Decay Damage to Mass Timber Elements in AWPA Ground Proximity and Above Ground Field Tests in Southern Mississippi

https://research.thinkwood.com/en/permalink/catalogue3236
Year of Publication
2022
Topic
Serviceability
Material
CLT (Cross-Laminated Timber)
Author
Mankowski, Mark E.
Shelton, Thomas
Kirker, Grant
Morrell, Jeffrey J.
Organization
Forest Products Laboratory
Year of Publication
2022
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Serviceability
Keywords
Mass Panel Plywood
Ground Proximity Test
Above Ground Test
Soil Termiticide
Field Test
Durability
Decay
Termite
Conference
Proc. of 118th annual meeting of American Wood Protection Association
Research Status
Complete
Summary
The ability of soil insecticidal drenches or spray-on insecticide/fungicide treatments to protect mass timber elements was assessed using two modified AWPA ground proximity tests established in 2017 and 2019. The 2017 test evaluated 3-ply Douglas-fir cross-laminated timber using a modified AWPA Standard E26 while the 2019 test used a modified AWPA E21 protocol to evaluate 3-ply Douglas-fir or southern pine cross-laminated timber as well as Douglas-fir mass plywood panels. Both tests were installed at the Harrison Experimental Forest (Saucier, Mississippi) and will be assessed for five years. Treatments include an initial soil termiticide drench, spray-on borate at initiation, borate rods at initiation, remedial boron spray treatment two years after installation, and untreated controls. Samples were left undisturbed for one or two years and then rated for degree of termite and fungal damage. Moisture content of the test materials increased greatly over the non-disturbance period. Untreated control samples were attacked by both decay fungi and termites within the first year after test initiation. Soil termiticide treated plots showed no sign of termite attack, but decay was evident on some samples compared to non-soil termiticide treated plots. Samples treated with borates at test initiation showed limited decay or termite attack. The tests will continue to be evaluated for a period of at least 5 years or longer and serve as critical baseline data for field evaluation methods of mass timber in areas of high subterranean termite and decay pressure.
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Improving durability of cross laminated timber (CLT) with borate treatment

https://research.thinkwood.com/en/permalink/catalogue3246
Year of Publication
2022
Topic
Serviceability
Material
CLT (Cross-Laminated Timber)
Author
Bagheri, Sajad
Alinejad, Mona
Ohno, Katie M.
Hasburgh, Laura E.
Arango, Rachel
Nejad, Mojgan
Organization
Forest Products Laboratory
Publisher
Springer
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Serviceability
Keywords
Borate
Durability
Flammability
Termite Resistance
Decay Resistance
Spray Treatment
Research Status
Complete
Series
Journal of Wood Science
Summary
Borate solution was used to treat two sets of Douglas-fr wood samples, one by spraying cross-laminated timbers (CLT) and another set by dip-treating wood in solutions at different retentions. A novel model was developed to explain and predict borate uptake based on dip-treatment parameters. Small-scale CLT samples were prepared using commercial emulsion polymer isocyanate (EPI) and polyurethane (PU) adhesive with dip-treated wood. The effect of adhesive and borate retention on CLT samples were evaluated through adhesion, fire, termite, and decay tests. The adhesion strength of wood was statistically unaffected by borate treatment. Statistical analysis showed that both spray- and dip-treated samples had significantly higher termite and decay resistance and fire performance than the untreated boards. Untreated CLT samples bonded with PU showed a considerably higher inherent decay and termite resistance than untreated specimens bonded with EPI adhesive.
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Development of a modified standard termite test for mass timber products

https://research.thinkwood.com/en/permalink/catalogue3252
Year of Publication
2022
Topic
Serviceability
Material
CLT (Cross-Laminated Timber)
Author
Franca, Tamara S.F.A.
Stokes, Elizabeth C.
Tang, Juliet D.
Organization
Mississippi State University
Forest Products Laboratory
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Serviceability
Keywords
Subterranean Termites
Laboratory Assay
Wood Durability
Research Status
Complete
Series
Wood and Fiber Science
Summary
US manufacturers are looking to expand the use of cross-laminated timber (CLT) panels into the North American market, including states located in the southeast where termites are important pests. However, there is no current assessment method for determining CLT vulnerability to the highly destructive native termites found in many states across the United States. The impact of damage by these termites is of particularly high interest in areas with suitable climate to their proliferation, such as the southeastern United States. This study evaluated durability of CLT panels and developed a laboratory assay to test susceptibility of this product to termites. Untreated CLT suffered mass losses of up to 5.8% in testing with an average visual rating of 7.2, indicating a moderate to severe attack with 10-30% of the cross section of the product affected by termite intrusion. Recommendations were developed for the inclusion of modifications presented in standardized testing protocols and will be presented to standards organizations. The proposed method may also be applied to evaluate termite resistance of other mass lumber products such as laminated veneer lumber and Glulam.
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Intermediate-Scale Laboratory Method to Qualify Heat-Delaminating Adhesives for Use in Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue3318
Year of Publication
2022
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Author
Zelinka, Samuel L.
Bourne, Keith J.
Organization
Forest Products Laboratory
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Fire
Keywords
Fire Tests
ANSI/APA PRG-320
Research Status
Complete
Series
Forest Products Journal
Summary
The goal of this research was to develop a simple laboratory test for examining heat delamination in cross-laminated timber (CLT) panels. The laboratory test was designed to mimic the fire tests described in Annex B of the ANSI/APA PRG-320 standard, which is required for CLT product qualification in North America. The Annex B test requires a full-sized room (2.4 by 4.9 by 2.7 m) to be constructed and exposed to a design fire scenario. In this article, we scaled the mechanical and fire loads so that they could be conducted in an intermediate-scale furnace with 1.1 m2 of exposed CLT panels. The mechanical loads were scaled to match the bending moment prescribed in the standard. The fire loads were scaled by matching the temperature profiles when an inert furnace lid was run and then matching the gas flow on all subsequent tests. Panels made from adhesives that passed the Annex B test passed the laboratory-scale test; panels that failed the Annex B test failed the laboratory test with the exception of one replicate. Correlations were found not only for CLT but also for a veneer-based mass timber panel. Measured temperature profiles within the furnace were similar to those measured near the compartment ceiling in the Annex B test. The scaled-down test in this article can be used to screen which adhesives are likely to pass the full-scale Annex B test.
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88 records – page 1 of 9.