COST Action E13 Wood Adhesion and Glued Products Working Group 2: Glued Wood Products State of the Art – Report Editors: Carl-Johan Johansson Tony Pizzi Marc Van Leemput 2nd Edition - August 2002 ISBN 92-894-4892-X COST Action E13 - WG 2 Report on the State of the Art The Authors: (in alphabetical order) Erik Aasheim [email protected] Norwegian Institute of Wood Technology P.O. Box 113 Blindern N-0314 OSLO Charlotte Bengtsson [email protected] Swedish National Testing and Research Institute P.O. Box 857 S-501 17 Borås Manfred Dunky [email protected] Dynea Austria GmbH Hafenstrasse 77 A-3500 Krems Rico Emmler [email protected] IHD-Institut für Holztechnik Dresden GmbH Zellescher Weg 24 D-01217 Dresden Athanassios Grigoriou [email protected] Aristotle University of Thessaloniki Dpt of Forestry and Natural Environment Lab. of Forest Technology GR-54006 THESSALONIKI Dirk Grunwald [email protected] Wilhelm-Klauditz-Institut (WKI) Bienroder Weg 54e D-38108 Braunschweig Per Johan Gustafsson [email protected] Lunds University of Technology Box 118 SE-221 00 LUND Wilfried Haelvoet [email protected] Belgian Institute for Wood Technology (CTIB-TCHN) Hof ter Vleestdreef, 3 B-1070 BRUSSELS Carl-Johan Johansson [email protected] Swedish National Testing and Research Institute P.O. Box 857 SE-501 15 BORAS Matti Kairi [email protected] Helsinki University of Technology Laboratory of Wood Technology P.O. Box 5100 FIN-02015 TKK August 2002 i COST Action E13 - WG 2 Report on the State of the Art Björn Källander [email protected] Swedish National Testing and Research Institute P.O. Box 857 S-501 17 Borås Detlev Krug [email protected] IHD-Institut für Holztechnik Dresden GmbH Zellescher Weg 24 D-01217 Dresden Simo Koponen [email protected] Helsinki University of Technology Laboratory of Structural Engineering & Building Physics P.O. Box 2100 FIN-02015 HUT Eva Martinez Martin [email protected] AIDIMA Valencia Parque Tecnológico Apdo. Benjamin Franklin, 13 SP 46980 PATERNA, Valencia George Ntalos [email protected] Technological Educational Institution of Larisa Department of Design and Technology for Wood and Furniture Terma Mauromihali GR 43100 Karditsa Frederic Pichelin [email protected] Schweizerische Hochschule für die Holzwirtschaft Abteilung F&E Solothurnstrasse 102 CH 2504 Biel Petri Pulkkinen [email protected] Helsinki University of Technology Laboratory of Wood Technology P.O.Box 5100 FIN-02015 TKK Murt Redington [email protected] Department of Materials Science & Techn University of Limerick National Technology Park Limerick IRELAND Klaus Richter [email protected] EMPA Dübendorf Überlandstrasse 129 CH-8600 Dübendorf August 2002 ii COST Action E13 - WG 2 Report on the State of the Art Alfred Teischinger [email protected] Institut für Holzforschung Universität für Bodenkultur Gregor-Mendelstraße 33 A-1180 WIEN Steffen Tobisch [email protected] Institut für Holztechnologie Dresden GmbH IHD Zellescher Weg 24 D-01217 DRESDEN M.L.R van der Linden [email protected] TNO Building and Construction Research Lightweight Buildings and Construction P.O. Box 49 NL-2600 AA DELFT (cid:150) (cid:150) (cid:150) Acknowledgement First of all I would like to express my gratitude to all who voluntarily and with no or limited funding have contributed to this report with the state-of-art within their research area. A special thank goes to Marc Van Leemput, the secretary of COST E13 managing committee, who had to handle the final editing of the report in an excellent way. Carl-Johan Johansson Chairman of COST E13 WG 2 – Glued products December 2001 August 2002 iii COST Action E13 - WG 2 Report on the State of the Art Preface By definition COST aims at developing cooperation in science ad technology in Europe. The technical Committee for Forests and Forestry Products recognized the great value that adhesives and bonding technology can apport and have apported to wood and to forest products. It is for this reason that COST E13 on wood adhesives and wood gluing has been created. The aims of this group are multifold, being: 1. To create a platform for building scientific cooperation and partnership across Europe and to facilitate the development of consortia for EU funded research projects (R&D framework programmes). 2. To assess the strength and weaknesses on given areas or disciplines concerning the field of wood adhesives and wood bonding for the various countries, and even more important for the European Community as a whole in relation to the global context. 3. To address such strengths and weaknesses with apt transnational projects and even facilitate national approach of such problems. 4. To make the scientific and industrial community in the wood adhesives and wood gluing cluster more visible and with greater lobbying influence in Europe and abroad. We have now completed the State of the Art report. I would like to emphasize the necessary and innovative aspects of this work. It is “Europe” with a single voice speaking for the first time through the pages of this report, through you which have contributed to write the different chapters, or that you have just contributed by voice or by organizing. This is an important exercise as it is only through the dedication of all of you that from such a document, the real, perceived, and urgent areas of need determinant for the future survival of this speciality and of its related industries have started already to emerge. We have a couple of years to go to define and refine these areas even better, in short to distil the numerous points we have already defined in a series of important focuses in the adhesives, bonding and bonded products areas. Take this seriously as you have taken extremely seriously the compilation of this State of the Art report, as your own survival in this field might depend from it, even if you might not be able to perceive this today. “Sitting on the fence”, and just playing at the stateman is a losing proposition in these exercises aimed at a world already in fast forward gear: not to participate actively means not to have your ideas taken into consideration, whatever these ideas and wishes might be: financing from the EU, a bigger market share on the global scene, an innovative product or process, impact on the world scientific stage, or even just survival by defending your own patch from unfriendly, competitive raids. The message is clear: participate actively as the future is only in your own hands. It is through this State of the Art report that each of you will also identify similarity of interests and purpose, will then identify future partners, lobbying friends and common interests without losing but rather gaining in competitive advantage at the cutting edge of the speciality. Do not waste or belittle this opportunity: none of us know, but it might be the only one is ever offered to us. A.Pizzi Chairman COST E13 August 2002 v COST Action E13 - WG 2 Report on the State of the Art Table of Contents Executive Summary.....................................................................................................................................viii 1. Introduction........................................................................................................................................1 1.1 General.................................................................................................................................................1 1.2 Non Structural Applications.................................................................................................................2 1.3 Structural Applications.........................................................................................................................4 1.4 Problems to Introduce New Products...................................................................................................5 2. Tests and Test Results on Mechanical Properties of Adhesive Bond Lines..................................7 2.1 Introduction and Bond Structural Hierarchy........................................................................................7 2.2 Strength and Stress Versus Deformation..............................................................................................7 2.3 Influence of State of Stress on Strength.............................................................................................18 2.4 Influence of Climatic Conditions on Strength....................................................................................18 2.5 Influence of Load Duration on Strength and Deformation.................................................................18 2.6 Other Factors that Influence of Bond Strength...................................................................................22 2.7 Research Needs on Mechanical Properties of Adhesive Bond Lines.................................................23 3. Materials...........................................................................................................................................25 3.1 Wood-Based Panels............................................................................................................................25 3.2 Glued Laminated Timber...................................................................................................................65 3.3 Structural Composite Lumber............................................................................................................69 4. Adhesive Joints.................................................................................................................................79 4.1 Stress Distribution and Strength Models............................................................................................79 4.2 Glued-In Rods..................................................................................................................................100 4.3 Finger Joints.....................................................................................................................................111 4.4 Glued/Screwed Joints/Screw Glued Wooden Structures..................................................................115 4.5 Wood/Non-Wood.............................................................................................................................120 5. Products / Components..................................................................................................................123 5.1 Introduction......................................................................................................................................123 5.2 Composite Beams and Columns.......................................................................................................124 5.3 Stressed Skin Panels.........................................................................................................................129 5.4 Wood Based Floor Coverings..........................................................................................................134 5.5 Joinery..............................................................................................................................................143 5.6 Gluing of Wood to Fibre Reinforced Plastics..................................................................................146 6. Emission..........................................................................................................................................151 6.1 Introduction......................................................................................................................................151 6.2 Overview on Emittable Substances..................................................................................................151 6.3 Test Methods for the Determination of Various Compounds in the Air..........................................153 6.4 Test Methods for the Emissions During the Production Process......................................................154 6.5 Test Methods for the Subsequent Emission.....................................................................................154 6.6 Emission During the Production Process.........................................................................................157 6.7 Regulations Concerning Emissions..................................................................................................159 6.8 Influences on the Various Emissions of Wood Based Panels..........................................................160 7. LCA – Reuse / Recycle...................................................................................................................167 7.1 Principles and Procedures of LCA...................................................................................................167 7.2 Forestry and Wood Products............................................................................................................170 7.3 Wood Adhesives..............................................................................................................................175 7.4 Glued Wood Products......................................................................................................................177 7.5 Glued Wood Products in Building Application................................................................................179 7.6 End of Life Options..........................................................................................................................182 7.7 Open Question and Research Needs.................................................................................................186 August 2002 vii COST Action E13 - WG 2 Report on the State of the Art Executive Summary This report presents the state-of-art of research and development in the area of glued products. The presentation is done on different system levels, from the adhesive bond lines, via glued materials and glued joints to products and components. In addition to this, emission and LCA aspects are covered. Except for giving the state-of-art the aim has been to identify the need for research in the different areas. After a short introduction the mechanical behaviour of adhesive bond lines is explained by a presentation of tests and test results in chapter 2. Short term as well as long-term behaviour is covered. Chapter 3 deals with adhesive bonded materials. Wood based materials, such as particleboard, MDF, OSB, plywood and solid wood panels are included, as well as glued laminated timber and structural composite lumber. Chapter 4 begins with a detailed description of the stress distribution of adhesive joints and of how the joint strength can be modelled. In addition to this different types of joints are presented, such as glued-in rods, finger joints, glued/screwed joints and wood/non-wood joints. Chapter 5 covers a number of adhesive bonded products and components, for example composite beams, laminated floors and joinery. Chapter 6 gives an overview of emittable substances from adhesives in the production of glued products and in the finished product. Test methods as well as the regulations concerning emissions are presented. Chapter 7, finally, deals with Life-Cycle Assessment (LCA), reuse and recycle of glued products. In a few cases there are sections in the report, which were planned, but no author was found or the material has not been presented in time. In those cases the heading is left in the report and hopefully the section can be completed if a new version of the report is published. August 2002 viii