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10 records – page 1 of 1.

Ability of Finger-Jointed Lumber to Maintain Load at Elevated Temperatures

https://research.thinkwood.com/en/permalink/catalogue1832
Year of Publication
2018
Topic
Fire
Material
Other Materials
Author
Rammer, Douglas
Zelinka, Samuel
Hasburgh, Laura
Craft, Steven
Publisher
Forest Products Laboratory
Year of Publication
2018
Country of Publication
United States
Format
Journal Article
Material
Other Materials
Topic
Fire
Keywords
Small Scale
Full Scale
Bending Test
Melamine Formaldehyde
Phenol-Resorcinol Formaldehyde
Creep
Polyurethane
Polyvinyl Acetate
Temperature
Durability
Language
English
Research Status
Complete
Series
Wood and Fiber Science. 50(1): 44-54.
Online Access
Free
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Effective Bonding Parameters for Hybrid Cross-Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue1368
Year of Publication
2017
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Author
Larkin, Blake
Organization
Oregon State University
Year of Publication
2017
Country of Publication
United States
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Connections
Keywords
North America
Low-Grade
Adhesives
Bond Integrity
Polyurethane
Phenol-Resorcinol Formaldehyde
Lodgepole Pine
Douglas-Fir
Hemlock
Manufacturing
Language
English
Research Status
Complete
Summary
Cross-laminated timber (CLT) is a massive engineered wood product made of orthogonally bonded layers of solid-sawn lumber, and is intended for roof, floor, or wall applications. Although it was developed in Europe in the early 90s, CLT is relatively new to North America. CLT products must be certified for structural use. First North American product standard stipulating test methods and qualification criteria for benchmark structural properties and adhesive bond integrity in structural CLT is ANSI/APA PRG320-2012. These methods and criteria have been adapted from existing laminated timber products (glulam), sometimes disregarding substantial differences between parallel laminates and CLT, in which layers are perpendicular to each other. From the point of view of long term sustainability of the CLT industry in North America, the critical questions are: 1. Is it possible to use low-grade timber harvested in the Pacific Northwest region in CLT products without compromising critical engineering parameters? Utilization of low- grade lumber, which is typically under-valued, in value-added engineered products should reduce the pressure on the high end structural lumber supply and may also provide a substantial outlet for lower-grade lumber timber species, including beetle-killed pine (BKP) harvested in the affected areas. 2. Can alternative adhesive systems, currently used in related engineered wood products and manufactured by domestic industry, be successfully used in CLT production? This is an important question, and is related to the fact that polyurethane (PUR) is the primary adhesive currently used by CLT manufacturing industry, and is supplied worldwide by a single Europe-based company. This adhesive is optimized for the species commonly used in CLT products to-date. ANSI/APA PRG320-2012 standard allows alternative adhesive types (PRF and EPI are specifically named), but to-date, only one alternative (MUF) has been used in commercial products. The objective of this project is to determine effective adhesive systems and bonding pressures for the hybrid cross-laminated timber (CLT) combinations. A secondary objective is to evaluate the testing methods prescribed in PRG 320-2012 for cross-laminated bond integrity. Integrity of hybrid CLT layups was evaluated on small specimens derived from CLT billets fabricated in-house using test procedures and qualification criteria specified in ANSI/APA PRG 320-2012 section 8.2.3. Test results were compared to prescribed qualification criteria. The Hybrid CLT combinations for this study include both structural grade lumber and low-grade lumber. For a reference species, lodgepole pine was selected, since it is a member of the US-SPF group closely related to the European species commonly used for CLT construction. The structural-grade, local species will be represented by Douglas-fir, while the low-grade species will be represented by low-grade lodgepole Pine, Douglas-fir, and Western Hemlock. The two adhesive systems investigated were 1) polyurethane-based PUR (currently the most common adhesive used by the CLT industry), which will serve as a reference system, and 2) phenol-resorcinol formaldehyde (PRF), which will represent a potential domestic alternative. PRF was chosen because it is a cold setting adhesive commonly used by the engineered wood products industry in North America; however, no CLT manufacturers utilize this adhesive system. The variables included species combinations (6), adhesive types (2), and clamping pressures (3), with repetition of 9 specimens per combination coming from at least three different CLT billets. The specimen’s bond integrity was assessed by the qualification panel requirements in PRG 320-2012 section 8.2. The qualification tests are block shear and cyclic delamination. A combination must pass both of the test requirements to qualify. The results of the study show that, of the 36 combinations, six failed the block shear test requirements and twenty-five failed the delamination test requirements. The 10 variable combinations that passed both requirements were DDL10F, DDL40F, DPL40F, PPH10F, PPH69F, PPH10U, PPH40U, PPL10U, PPL69U, and PHL69U. Initial inspection of test results show that no single variable that seems to make a significant impact on the bond integrity. It did reveal that no combinations with the use of Douglas-fir as a face material and PUR as an adhesive met the requirement, and only one combination with western hemlock as a core material met the requirements. It is evident that the delamination test was the major restriction on whether or not a combination passes the bond qualification. We believe that the adaption of a delamination test standard designed for layers with parallel grains makes the passing requirement too strict for an orthogonally bonded product. In conclusion, there were 10 combinations that passed both bond integrity test requirements. It was unclear whether the species and/or grade combination, adhesive system, or clamping pressure made the biggest impact on the bond integrity. Relative to the reference adhesive (PUR), and species combination (lodgepole pine), the hybrid panels performed similarly and showed that certain species and/or grade combinations could pass the qualification requirements for specific requirements. The knowledge gained by this screening study will allow further qualification testing of the passing combinations per PRG320-2012. This also has the potential to supply the CLT manufacturing community with greater flexibility of manufacturing techniques and materials, as well as offer value to underutilized lumber.
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Effect of Adhesives and Ply Configuration on the Fire Performance of Southern Pine Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue1682
Year of Publication
2016
Topic
Connections
Fire
Material
CLT (Cross-Laminated Timber)
Author
Hasburgh, Laura
Bourne, Keith
Peralta, Perry
Mitchell, Phil
Schiff, Scott
Pang, Weichiang
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Fire
Keywords
Southern Pine
Adhesives
Ply Configuration
Fire Performance
Melamine Formaldehyde
Phenol-Resorcinol Formaldehyde
Polyurethane
Emulsion Polymer Isocyanate
Delamination
Char Rate
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 4031-4038
Summary
Thirteen Southern pine cross-laminated timber panels were tested in the intermediate scale horizontal furnace at the Forest Products Laboratory to determine the effects different adhesives and ply configuration had on fire performance. Four different adhesives were tested: melamine formaldehyde (MF), phenol resorcinol formaldehyde (PRF), polyurethane reactive (PUR), and emulsion polymer isocyanate (EPI). There were two ply configurations: Long-Cross-Long (LCL) or Long-Long-Cross (LLC) where “long” indicates the wood was parallel to the longer edge of the panel. The MF and the PRF prevented delamination and associated problems while the LLC configuration resulted in uneven charring patterns.
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Free
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Estimation of Radio Frequency Electric Field Strength for Dielectric Heating of Phenol-Resorcinol-Formaldehyde Resin Used for Manufacturing Glulam

https://research.thinkwood.com/en/permalink/catalogue1505
Year of Publication
2014
Topic
Connections
Material
Glulam (Glue-Laminated Timber)
Author
Yang, Sang-Yun
Han, Yeonjung
Park, Yonggun
Eom, Chang-Deuk
Kim, Se-Jong
Kim, Kwang-Mo
Park, Moon-Jae
Publisher
The Korean Society of Wood Science Technology
Year of Publication
2014
Country of Publication
Korea
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Connections
Keywords
Adhesives
Phenol-Resorcinol Formaldehyde
Larch
High Frequency
Specific Heat
Density
Dielectric
Language
Korean
Research Status
Complete
Series
Journal of the Korean Wood Science and Technology
Summary
For enhancing productivity of glulam, high frequency (HF) curing technique was researched in this study. Heat energy is generated by electromagnetic energy dissipation when HF wave is applied to a dielectric material. Because both lamina and adhesives have dielectric property, internal heat generation would be occurred when HF wave is applied to glulam. Most room temperature setting adhesives such as phenol-resorcinol-formaldehyde (PRF) resin, which is popularly used for manufacturing glulam, can be cured more quickly as temperature of adhesives increases. In this study, dielectric properties of larch wood and PRF adhesives were experimentally evaluated, and the mechanism of HF heating, which induced the fast curing of glue layer in glulam, was theoretically analyzed. Result of our experiments showed relative loss factor of PRF resin, which leads temperature increase, was higher than that of larch wood. Also, it showed density and specific heat of PRF, which are resistance factors of temperature increase, were higher than those of wood. It was expected that the heat generation in PRF resin by HF heating would occur greater than in larch wood, because the ratio of relative loss factor to density and specific heat of PRF resin was greater than that of larch wood. Through theoretical approach with the experimental results, the relative strengths of ISM band HF electric fields to achieve a target heating rate were estimated.
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Free
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Feasibility of Glued Laminated Timber Beams with Tropical Hardwoods

https://research.thinkwood.com/en/permalink/catalogue118
Year of Publication
2013
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Bourreau, Damien
Aimene, Yamina
Beauchêne, Jacques
Thibaut, Bernard
Publisher
Springer
Year of Publication
2013
Country of Publication
Germany
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Delamination
Hardwood
Phenol-Resorcinol Formaldehyde
Shear
Testing
Tropical Climate
Language
English
Research Status
Complete
Series
European Journal of Wood and Wood Products
ISSN
1436-736X
Summary
A feasibility study of glulam was carried out in French Guiana using local wood species. The aim was to determine gluing parameters affording satisfactory behaviour to manufactured glulam in a tropical climate. Three abundant wood species, with special properties, were selected for the study and Resorcinol-Phenol-Formaldehyde resin was used for bonding. Three industrial parameters were considered: adhesive spread rate, closed assembly time and gluing pressure. Delamination and shearing tests were carried outin accordance with European Standards. The tests revealed the influence of wood properties and manufacturing parameters on joint resistance. In fact, the results showed that specific gravity and the shrinkage coefficientgreatly influenced the gluing step. Indeed, wood with a medium specific gravity needed more adhesive and more pressure than wood with a high specific gravity. In addition, planning and lamella thicknesswere found to affect glue joint resistance.
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Free
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Fire Safe Glued Massive Timber Members Adhesive Bonding Performance under Elevated Temperature -Tests Report

https://research.thinkwood.com/en/permalink/catalogue169
Year of Publication
2013
Topic
Fire
Mechanical Properties
Material
Solid-sawn Heavy Timber
Author
Zhang, Chao
Yan, Huijun
Lee, George
Lam, Frank
Organization
Forestry Innovation Investment
Year of Publication
2013
Country of Publication
Canada
Format
Report
Material
Solid-sawn Heavy Timber
Topic
Fire
Mechanical Properties
Keywords
Temperature
Adhesives
Bondlines
Polyurethane
Douglas-Fir
Hemlock
SPF
Phenol-Resorcinol Formaldehyde
Epoxy
Language
English
Research Status
Complete
Summary
This project was conducted to quantify the performance of adhesives bond lines under shear load subject to elevated temperature. The results add to the understanding of the performance of polyurethane adhesive bond lines under elevated temperatures to address areas of fire safety concern under the current building codes. The project focused on studying the shear bond capacity of three wood species by using 3 types of adhesives with/without nanoclay treatment at 4 temperature levels. The three wood species are Douglas-Fir, Hemlock and SPF. The adhesives are polyurethane (PU), Phenol-Resorcinol-Formaldehyde (PRF) and Epoxy. PU and PRF specimens were also tested with nanoclay treatment and without nanoclay treatment. Epoxy specimens were tested without nanoclay treatment only. The temperature levels considered were room temperature (about 20 °C), 60°C, 80°C and 100°C. The results indicate that the influence of elevated temperature on the shear bond strength of PU and PRF adhesive was in the range of 20 to 30% regardless of nanoclay treatment. Regardless of species, PU or PRF, with or without nanoclay, the average shear strength for 100°C oven temperature treatment ranged from 6.0 to 7.5 MPa. In the case of SPF PU specimens treatment with nanoclay reduced the variability of shear strength significantly from 12% at room temperature to 5% after 100°C oven treatment. This is an important aspect that needs further verification for enhancement of performance. Finally the data in this study can be used to support modeling of timber component subjected to elevated temperature.
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Free
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Investigation of Gluelines Block Shear Strength of Norway Spruce Glulam Joints in a Cold Climate

https://research.thinkwood.com/en/permalink/catalogue526
Year of Publication
2016
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Wang, Alice
Björnberg, Jonatan
Hagman, Olle
Ahmed, Sheikh
Wan, Hui
Niemz, Peter
Publisher
North Carolina State University
Year of Publication
2016
Country of Publication
United States
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Melamine Urea Formaldehyde
Phenol-Resorcinol Formaldehyde
Adhesives
Block Shear Strength
Temperature
Climate
Melamine Formaldehyde
Language
English
Research Status
Complete
Series
BioResources
Summary
Cross laminated timber (CLT) has been developed to a worldwide well-known and versatile useable building material. Currently increasing rates in production volume and distribution can be observed. In fact CLT, thanks to its laminar structure making it well suited for use in construction, provides new horizons in timber engineering, in areas which had until now been the realm of mineral building materials like concrete and masonry. After a short introduction, this paper aims to demonstrate current production processes used for rigid CLT. In section 2 the process steps are described and essential requirements, as well as pros and cons of various production techniques, are discussed. Latest results of R & D and of development and innovation in production technology are presented. In section 3 test and monitoring procedures in the area of the internal quality assurance, known as factory production control (FPC), are presented. Diverse regulations, in the form of technical approvals for CLT as well as in the CLT product standard prEN 16351 [1], are discussed. Additionally, some technological aspects of the product, CLT, together with a comparison of geometrical and production relevant parameters of current technical approvals in Europe are provided in section 4. In the final and main part of the paper, production and technology is presented in a condensed way. The outlook for current and future developments, as well as the ongoing establishment of the solid construction technique with CLT, is given. The product, CLT, comprises an enormous potential for timber engineering as well as for society as a whole. Standardisation and further innovation in production, prefabrication, joining technique, building physics and building construction make it possible for timber engineering to achieve worldwide success.
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Free
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Performance of Glue-Laminated Beams from Malaysian Dark Red Meranti Timber

https://research.thinkwood.com/en/permalink/catalogue1822
Year of Publication
2018
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams

Physical and Mechanical Properties of Glued-Laminated Lumber from Fast-Growing Tree Species Using Mahogany Tannin Adhesive

https://research.thinkwood.com/en/permalink/catalogue2473
Year of Publication
2019
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Lestari, Andi Sri Rahayu Diza
Hadi, Yusuf Sudo
Hermawan, Dede
Santoso, Adi
Pizzi, Antonio
Publisher
Society of Wood Science and Technology
Year of Publication
2019
Country of Publication
United States
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Tannin
Resorcinol Formaldehyde
Language
English
Research Status
Complete
Series
Wood Material Science & Engineering
Online Access
Free
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Shear Strength and Durability Testing of Adhesive Bonds in Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue535
Year of Publication
2015
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Sikora, Karol
McPolin, Daniel
Harte, Annette
Publisher
Taylor&Francis Online
Year of Publication
2015
Country of Publication
United Kingdom
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Phenol-Resorcinol Formaldehyde
Polyurethane
Adhesives
Block Shear Tests
Shear Strength
Language
English
Research Status
Complete
Series
The Journal of Adhesion
Summary
This paper addresses the quality of the interface- and edge-bonded joints in layers of cross-laminated timber (CLT) panels. The shear performance was studied to assess the suitability of two different adhesives, polyurethane (PUR) and phenol–resorcinol–formaldehyde (PRF), and to determine the optimum clamping pressure. Since there is no established testing procedure to determine the shear strength of the surface bonds between layers in a CLT panel, block shear tests of specimens in two different configurations were carried out, and further shear tests of edge-bonded specimen in two configurations were performed. Delamination tests were performed on samples which were subjected to accelerated aging to assess the durability of bonds in severe environmental conditions. Both tested adhesives produced boards with shear strength values within the edge-bonding requirements of prEN 16351 for all manufacturing pressures. While the PUR specimens had higher shear strength values, the PRF specimens demonstrated superior durability characteristics in the delamination tests. It seems that the test protocol introduced in this study for crosslam-bonded specimens, cut from a CLT panel, and placed in the shearing tool horizontally, accurately reflects the shearing strength of glue lines in CLT
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10 records – page 1 of 1.