THERMAL CONDUCTIVITY OF CROSS LAMINATED TIMBER (CLT) WITH A 45˚ ALTERNATING LAYER CONFIGURATION

Abstract

Cross-laminated timber (CLT) has increasingly become a viable alternative to other structural materials, mainly because of its excellent properties related to sustainability, energy efficiency, and speed of construction. This has resulted in the recent emergence of a significant number of CLT buildings constructed around the world. Cross-laminated timber panels consist of lumber boards stacked and glued in layers, which run perpendicular to each other, making them dimensionally stable with high in- and out-of-plane strength and stiffness. Thermal conductivity is used to estimate the ability of insulation of material. Thermal conductivity of wood material has varied according to wood species, direction of wood grain, specific gravity, moisture content, resin type, and addictive members used in manufacture of wood composite panels. The aim of this study is the comparison of two types of CLT panels consisting of boards either with grain direction aligned at 45˚ or at 90˚, in terms of their insulation properties. In the study, spruce (Picea orientalis L.) was used as a wood species, and was used polyurethane for CLT panels. Thermal conductivity of CLT panels was determined according to ASTM C 518 & ISO 8301. As a result of this study, it was indicated that thermal conductivity values for 90˚ layers were higher than the values for 45˚ layers.

Keywords

• Cross-laminated Timber
• Grain Direction
• Spruce
• Thermal Conductivity

References

1. Aydin I., Demir A., and Ozturk H. (2015). Effect of Veneer Drying Temperature on Thermal Conductivity of Veneer Sheets. Pro Ligno, 11(4), 351-354.
2. Bader H., Niemz P., and Sonderegger W. (2007). Untersuchungen zum Einfluss des Plattenaufbaus auf Ausgewählte Eigenschaften von Massivholzplatten. Holzals Roh- und Werkstoff, 65(3), 173–81.
3. Bolvardi V., Pei S., Lindt J.W. and Dolan J.D. (2018). Direct Displacement Design of Tall Cross Laminated Timber Platform Buildings with Inter-Story Isolation. Engineering Structures 167, 740–749.
4. Buck D., Wang X., Hagman O. and Gustafsson A. (2016). Bending Properties of Cross Laminated Timber (CLT) with a 45° Alternating Layer Configuration. BioResources 11(2), 4633-4644.
5. Festus T.L., Onah B.T., Okpe B.O. and Josiah O. (2017). The Effect of Temperature and Grain Directions on the Thermal Conductivity of Woods. International Journal of Advance Research, IJOAR .org, 4(6).
6. Fredriksson Y. (2003). Collaboration Between the Wood Component Manufacturers and Large Construction Companies: A study of Solid Wood Construction. Licentiate thesis. Luleå University of Technology, Sweden.
7. Gu H.M and Zink-Sharp A. (2005). Geometric Model for Softwood Transverse Thermal Conductivity. Part 1. Wood and Fiber Science 37(4), 699-711.
8. He M., Sun X. and Li Z. (2018). Bending and Compressive Properties of Cross-laminated Timber (CLT) Panels Made From Canadian Hemlock. Construction and Building Materials 185, 175–183.

9. Izzi M., Casagrande D., Bezzi S., Pasca D., Follesa M. and Tomasi R. (2018). Seismic Behaviour of Cross Laminated Timber Structures: A state-of-the-art review, Engineering Structures. 170, 42–52.
10. Kawasaki T. and Kawai S. (2006). Thermal Insulation Properties of Wood-based Sandwich Panel for Use as Structural Insulated Walls and Floors. J Wood Sci., 52:75–83
11. Kilic Y., Colak M., Baysal E. ans Burdurlu E. (2006). An Investigation of Some Physical and Mechanical Properties of Laminated Veneer Lumber Manufactured From Black Alder (Alnus glutinosa) Glued with Polyvinyl Acetate and Polyurethane Adhesives. Forest Products Journal. 56(9), 56-59.
12. Sahin Kol H. and Altun S. (2009) Effect of Some Chemicals on Thermal Conductivity of Impregnated Laminated Veneer Lumbers Bonded with Poly(Vinyl Acetate) and Melamine–Formaldehyde Adhesives. Drying Technology 27:1010–1016.
13. Sahin Kol H. and Altun S. (2009) Effect of Some Chemicals on Thermal Conductivity of Impregnated Laminated Veneer Lumbers Bonded with Poly(Vinyl Acetate) and Melamine–Formaldehyde Adhesives. Drying Technology 27:1010–1016.
14. Sekino N. (2016). Density Dependence in The Thermal Conductivity of Cellulose Fiber Mats and Wood Shavings Mats: Investigation of The Apparent Thermal Conductivity of Coarse Pores, J. Wood Sci., 62, 20–26.
15. Seo J., Jeon J., Lee J.H. and Kim S. (2011). Thermal Performance Analysis According to Wood Flooring Structure for Energy Conservation in Radiant Floor Heating Systems. Energy and Buildings 43 (2011) 2039–2042.
16. Sonderegger W. and Niemz P. (2009). Thermal Conductivity and Water Vapor Transmission Properties of Wood Based Materials. Eur J Wood Wood Prod., 67, 313–21.
17. Suleiman B.M., Larfeldt J., Leckner B. and Gustavsson M. (1999). Thermal Conductivity and diffusivity of wood. Wood Sci Technol, 33(6):465–73.
18. Sullivana K., Miller T. H. and Gupta R. (2018). Behavior of Cross-laminated Timber Diaphragm Connections with Self-tapping Screws. Engineering Structures. 168, 505–524.
19. TS EN 322, (1999). Wood-based panels-Determination of moisture content. Turkish Standards Institute, Ankara.