Dendrolight, Engineered Wood Construction Material - Book Report/Review Example

DendrolightTM – Engineered wood construction material Introduction A new type of engineered wood has made its appearance in the UK market in 2010 called Dendrolight. The name comes from the Greek name for a tree, “dendros”. The product is made in Latvia which is emerging as a major wood industry centre in Europe due to the abundant forest cover in the country. Dendrolight is processed from softwoods like Pine, Spruce and Aspen. The product is made lighter by machining grooves in the wood to create voids. This paper describes the manufacturing process used to make the product, the properties and the advantages and possible disadvantages of the product. 2. Dendrolight manufacturing process The manufacturing process for Dendrolight starts with sawn planks of wood received from a saw mill. The central plate called the lamella is made from the softwood plank by sawing it into a comb-like structure as shown in the picture on the left. Alternate layers of these sawed combs are glued turned 900 to each other as shown in the picture on the right which gives the structure its rigidity. Solid wood external trims are added, again by gluing, to form a completed panel. Depending on the strength and rigidity needed, the sawed wood structures can be made in different formations as shown below. Note that in the lower picture, the end-pieces are sawed at a 450 angle. The upper picture has another variant of shape for the end-piece (Lathams, 2012). The creation of voids in the panel is at the core of the Dendrolight technology. This reduces the weight of the panel without sacrificing strength or rigidity. This is the core idea for which the inventor of the product, Johann Berger of Austria has been granted a patent. This process in Dendrolight reduces the wood content of the panel to 40% and the material reaches a weight as low as 250 kg per cubic meter. For comparison, Aspen wood has a weight of 420 kg per cubic meter, Spruce wood has a weight of 450 kg per cubic meter and Pine depending on the species, has a weight between 350 and 660 kg per cubic meter (Simetric, 2011). This weight is also significantly lower than other engineered wood panels including plywood, particle board, MDF and Oriented Strand Board which are in the range 400 – 700 kg per cubic meter (Berger, 2006). The sawed middle layers are built up by gluing to blocks of the maximum size of 3 meters length, 1.35 meters width and 600 mm thickness. From this block, pieces are cut by band saw to the desired dimensions. The thickness can range from 14 mm to 200 mm. The band saw cut customised pieces are finished by adding face layers on both sides, made of plywood or any other desired material of 3 mm to 6 mm thick. The faceplates are also glued to the lamella middle layer. 2. Dendrolight technical advantages The inventor and patent holder, Johann Berger, in a presentation at a technical conference in 2006 has listed the following advantages for the Dendrolight wood (Berger, 2006). Adhesive content in the board is only 3-4 % which makes the material strength unaffected by heat and damp. The construction of the middle layer with vertical comb-shaped boards and horizontal webs gives a more homogeneous structure and greater mechanical stability (Ecobuild, 2012). The solid wood core of Dendrolight gives superior screw holding properties than other engineered wood products which often need special fasteners. He has shown by tests that the screw withdrawal force in Dendrolight blocks is between 51 kg and 78 kg which is comparable to the screw withdrawal force in solid wood. Berger has also shown that Dendrolight panels have compression strength in the range of 2 Newtons per square mm. This too is comparable with solid wood. Tests have sown that mechanical bonding strength in these panels is inherently higher at 2.5 Newtons per square mm. It is lower in at around 0.5 Newtons per square mm in other engineered wood products since the internal bonding is through resins not the parent material. Thickness swelling in Dendrolight panels is 2-4%. (Iejavs & Spulle, 2010). It is much higher at 8-15% in particle board, MDF or OSB Particle boards exhibit creep behaviour under permanent loading (such as in shelves) whereas Dendrolight shows negligible creep. Dendrolight has less flame propagation than other engineered materials. 3. The use of voids in materials to reduce weight The Dendrolight wood processing method essentially creates air voids within the structure to reduce weight. This idea is applied in many different materials and applications. The two examples shown above represent perhaps two extremes for the usage of hollow materials. The hollow concrete blocks used in building construction use voids to reduce the amount of cement concrete used in construction and in many cases are stronger than solid concrete blocks. The air voids also improve thermal and acoustic insulation of the building (CBA, 2007). The example on the right is the use of fluting between cardboard paper sheets used for packing to increase their strength and the property of shock absorption (Eng-tips, 2003). 4. Potential disadvantages of the material Since this is a new material in the market, all the published information is from the manufacturer or his agents which speak mainly of the advantages of the product and do not talk of any disadvantages. However, some of the possible disadvantages are as below. UK consumed a total of about 13.7 million cubic metres of wood products in 2011 valued at about £ 3.13 billion. This included 3.02 million cubic meters of particle board, 1.2 million cubic meters of Medium Density Fibreboard (MDF) and 1.26 million cubic meters of plywood (TTF, 2012). These are the materials that Dendrolight will compete with. The total production capacity for this new material is only 7000 square meters a year in various thicknesses (Dendrolight Latvia, 2012). Dendrolight can therefore only be a material for specialised niche applications and not a significant construction material. There is no published pricing information to compare prices with competing materials. The manufacturing process requires machining of wood as an additional process over competing materials like MDF. The process also uses sawn timber planks which are more expensive than the wood chips used in MDF manufacture. Dendrolight should therefore be significantly ore expensive than MDF. The Dendrolight machining process removes about 40% to 50% of wood which becomes sawdust, a low value waste product. The waste material has to be processed into a particle board or used to produce ethanol or other products close to factory as transporting of sawdust is expensive. Dendrolight will be considered for use mainly in applications where its light weight will be the principal attraction compared to other engineered wood materials. In such applications, it could also face competition from lower price polymer or thermoplastic materials which can be provided with wood veneers to resemble wood. 5. Conclusion Dendrolight is an interesting new material that has become available to the construction industry. There is insufficient evidence, other than the manufacturer’s claims on the benefits of this new material other than the fact that it is significantly lighter than all forms of wood. The principle of creating air pockets or voids in solid materials to reduce weight without sacrificing strength or rigidity is well known in engineering sciences. The application of these principles to wood processing is an important advance and is sure to lead more researchers to apply this idea to other forms of wood processing. The total production volumes for this new material are still too small for it to be used as a significant construction material. Dendrolight will probably get used by architects or interior decorators to create some applications where they need the light weight and the rich, natural appearance of wood. Those applications could trigger thinking on newer applications. * * * * References: 1. Berger, J., (2006). “Dendrolight Properties and Performance”, 2006. (Accessed on 6 Jan 2013 at www.docstop.com) 2. CBA, (2007). “Concrete blocks – Guide to selection and specification”, Concrete Blocks Association, 2007. (Accessed on 7 Jan 2013 at www.cba-blocks.org) 3. Dendrolight Latvia (2012). Web-site www.dendrolight.lv 4. Ecobuild, (2012). “Future of the engineered solid wood – how far we can go?”, 2 Feb 2012. (Accessed on 8 Jan 2013 at www.ecobuild.co.uk) 5. Eng-tips, (2003). “Corrugated cardboard specifications”, Eng-tips, 2003. (Accessed on 7 Jan 2013 at www.eng-tips.com) 6. Iejavs, J. and Spulle, U., (2010). “Dendrolight panels produced from Aspen wood”, Tallinn University of Technology, Estonia, October, 2010. (Accessed on 8 Jan 2013 at www.nordicforestresearch.org) 7. IFC, (2007). “Sawmilling and Manufactured Wood Products”, IFC, 30 April 2007. (Accessed on 7 Jan 2013 at www1.ifc.org) 8. Lathams, (2012). “The future of engineered wood”, Lathams Ltd., 2012. (Accessed on 8 Jan 2013 at www.lathamtimber.co.uk) 9. Simetric, (2011). “Weight of various types of wood”, Simetric, 2011. (Accessed on 6 Jan 2013 at www.simetric.co.uk) 10. TTF, (2012). “Statistical Review 2012”, Timber Trade Federation, 2012. (Accessed on 6 Jan 2013 at www.ttf.co.uk) Read More