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Evaluation of the Bonding Quality of E. grandis Cross-Laminated Timber Made With a One-Component Polyurethane Adhesive

https://research.thinkwood.com/en/permalink/catalogue2369
Year of Publication
2018
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Author
Dugmore, Michael
Publisher
Stellenbosch University
Year of Publication
2018
Country of Publication
South Africa
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Topic
Design and Systems
Keywords
Polyurethane
Panels
Bond Performance
Bond Quality
Durability Assessment
Language
English
Research Status
Complete
Summary
Eucalyptus grandis is South Africa‘s most important commercial hardwood species. The availability of E. grandis and its fast growth rate creates the opportunity to explore its uses further. Cross-laminated timber (CLT) is a prefabricated multilayer engineered panel product made of at least three layers, with the grain direction of some or all of the consecutive layers orthogonally orientated. In order to add value to E. grandis, reduce the export of low-cost chips, increase the profit margins of local plantation owners and create jobs, the development of E. grandis CLT in South Africa may be an option. There is concern among some researchers that the bonding quality evaluation tests proposed by CLT standards have been developed for glulam and are too severe for CLT. These researchers proposed that further analysis and possibly even revision of the test methods should be considered. There is also a need to evaluate the mechanical properties of CLT panels made of E. grandis to completely understand the structural performance of these panels, including their bond quality and durability, and therefore be able to rely on E. grandis CLT as a construction material. The objectives of this study were: . To evaluate the face-bonding quality of CLT panels from E. grandis timber bonded with a one component polyurethane resin; . To determine the influence of material and processing parameters on the face-bonding quality of CLT manufactured from E. grandis timber bonded with a one component polyurethane resin; . To analyse different testing methods for evaluating the face-bonding quality of CLT. The design for this experiment consisted of eight groups with different combinations of parameters for density, grooves and pressure per group. Four different testing methods were used to evaluate the face-bonding quality of CLT panels from E. grandis and to determine the effect of parameters on face-bonding quality: A delamination test on 100 x 100 mm block specimens (Test A), a shear test on 40 x 40 mm specimens (Test B), a shear test on 40 x 40 mm specimens with grain direction 45° to load direction (Test C) and a combined delamination and shear test on 70 x 70 mm specimens with grain direction 45° to load direction (Test D). Results of the statistical analysis indicated that E. grandis CLT made with 1C-PUR adhesive can obtain excellent face-bonding quality using a clamping pressure of 0.7 MPa and with no stress relief grooves present. All samples passed the shear test (Test B) which is the reference test method proposed by EN 16351 (2015). It was found that a strength component and durability component will be an advantage when testing the bond quality of CLT. Shear tests at 45° to the load direction did not completely eliminate the rolling shear effect. The combined delamination and shear test (Test D), seems to have potential as a good test for bond quality since it is a combination of a durability and shear strength test. There are still questions about the relative advantages of specific test methods for bond quality, especially on the effect of rolling shear. Further work should focus on this aspect and the use of stress models might be a way of gaining further insights.
Online Access
Free
Resource Link
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UT System : A Structural System to Build Taller Urban Timber Houses with Aspired Spatial Flexibility

https://research.thinkwood.com/en/permalink/catalogue277
Year of Publication
2014
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Silva, Catarina
Branco, Jorge
Lourenço, Paulo
Organization
International Association for Housing Science
Year of Publication
2014
Country of Publication
Portugal
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Design and Systems
Keywords
Urban Densification
Tall Timber
Urban Timber (UT) System
Moisture
Durability
Fire Resistance
Acoustic Performance
Joints
Language
English
Conference
40th IAHS World Congress on Housing
Research Status
Complete
Notes
December 16-19, 2014, Funchal, Portugal
Online Access
Free
Resource Link
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