Wood-based products: is wood the material of the future?

Wood-based products: is wood the material of the future?
© Istock-Safak/Oguz

Professor Frédéric Pichelin discusses some of the ways in which wood can come to replace other materials across a wide range of sectors and describes some of the challenges that many wood-based products are facing.

Wood and wood-based products have huge potential across a range of sectors, from aerospace to musical instruments, furniture, and construction. With new technologies emerging to help enhance many of the material’s properties – including fire resistance and strength – these potential application areas are expanding. However, challenges to a wider acceptance and utilisation of wood-based products remain.

At Bern University of Applied Sciences, the Architecture, Wood and Civil Engineering department focuses on areas such as: developing materials; construction, which includes the investigation of issues relating to the design and construction of wooden structures, to working with existing buildings and to optimising and further developing wood and hybrid construction; the built environment, with the aim of finding solutions for future urban development; and business, production and construction processes, market research and business models.

In an interview with SciTech Europa, the department’s Professor Frédéric Pichelin discusses both the applications of wood-based products and many of the challenges that technologies are facing, and describes some of the work that is taking place which, hopefully, will enable wood to compete with other materials such as concrete and steel.

How would you describe the way in which the wood-based products industry has developed in recent years?

There are perhaps two key characteristics here. Firstly, wood-based products (especially things like wood biomass) has a great potential to help solve the challenge of climate change. Second, what we have seen both via our own research and in the efforts that are taking place around the world, is that R&D is increasingly geared towards helping industry to use wood in all its possible forms. This includes things like cross-laminated timber (CLT), chipboard, and fibre board. And increasingly, technologies such as nano cellulose are being validated, and numerous new biochemical plants are being built which are helping to significantly scale up producing.

However, wood-based products, of course, still must compete with other materials, such as plastic, concrete, and steel, and, unfortunately, the price of crude oil is still so low that there is no motivation for the markets to change their position, and so plastic remains the popular choice.

The European Commission is helping here by bringing in new regulations to curb the use of plastic. However, it nevertheless remains the case that it is often cheaper to import plastic products from other countries, such as China, than it is to invest in the development of other, new technology solutions, such as those based on wood. As such, we now need companies to invest in the technologies while they are at the early stage; we need them to trust in the technologies and help them to evolve so that they can then be rolled out further.

What do you think needs to happen in order to bring investors in and ensure that they see such investments as important long term activities? And does more need to be done to boost the level of investment available?

Yes, more definitely needs to be done across the board, and an important part of this involves educating people about the need to create start-ups and the importance of taking risks. We are therefore working to motivate investors and to find people who understand the technology and trust it.

Many European countries have a classical funding model, and there is now a sense that we need to look outside of that, to things like crowdfunding, for instance. Indeed, this is something I am now considering for a project I have in the Philippines which is looking at producing coco boards – pure bio-based boards which can be used in the construction sector – and I need to obtain a €5m investment; I am looking for somebody who will trust in this technology and invest in it in the long term, but that is a challenge.

What are your thoughts on how wood densification and wood mineralisation can help to develop a bio-based material with outstanding properties such as fire resistance or biological resistance against wood destroying fungi?

These are two technologies which, while dissimilar from a technical point of view, do lead to similar product properties. We know that wood has some good fire resistance, but this is nevertheless limited and, what is more, when it is used in a humid condition then fungi will become attached which causes degradation, and so on.

These can be some of the reasons why some people may continue to choose concrete or steel over wood-based products. Regarding wood mineralisation, the idea is to reproduce the properties that are found in the naturally mineralised trees that we see in Arizona, USA, where the wood has undergone a long term process of mineralisation which has resulted in the trees becoming stone-like. We reproduce this by introducing mineral salt to the wood in a small quantities, and we close all the cells and the lumens, resulting in a product with enhanced fire resistance which has applications in multi-story buildings. We are mow developing this technology with industry partners. This technology also has enhanced fungi resistance, so also has applications for outdoor flooring.

The main aim of wood densification is, as the name of the technology suggests, is to increase the density of wood, which is a low density material. By applying pressure to the wood, it is possible to change both its density and colour; the increase in density enhances the wood’s strength, bringing it closer to other metal materials in terms of its properties and load bearing potential. It can also be easily recycled and used for chip board at the end of its life.

The colour change means that wood that has undergone the densification process can have applications in things like musical instruments and furniture, where it can be used to imitate wood such as teak and ebony.

How important is it to further explore issues such as the high amount of leached out chemicals (which may be attributed to the by-product potassium chloride, as well as unreacted calcium chloride and potassium oxalate) observed in such technologies?

We are currently conducting this research at a small scale in the lab, and there is therefore no concerns around environmental toxicity etc. Furthermore, the methods do not use any toxic or dangerous substances – essentially, we use the same salt that is used on our roads in the winter to guard against ice and snow – and so even if there were to be a degree of leaching from one of these products in a building, it is not a significant concern.

Nevertheless, we are working to address this as much as possible during the process itself by enhancing further the bonding between the wood and the salts. To validate the technology we are using long term leaching tests akin to those used to test copper which can be impregnated using the same process.

We are confident that this issue can be solved and we are now taking steps with industry to produce large batches of these materials.

Linear vibration welding technology is a new approach to the welding of wood. What will be the biggest areas to benefit from this? Is more research required to ensure that this can be more widely rolled out?

This is an interesting topic. In this area, we use similar machinery to that found in the plastic industry. However, while the technology has, in my opinion, reached a stage where it is now suitable for the market – we have tested this with many industrial companies – and has applications in the production of simple panelling for furniture, for instance – we are again experiencing the problem of finding an initial investor.

The machinery costs around €0.5m, and so this is a significant level of investment. As such, while we have already worked with companies who have had proven successes with this technology – these include a company which makes barrels, and another which produces snowboards – we have yet to find an investor or company with both the necessary funds and the courage to make a riskier investment than they would perhaps usually consider.

We believe that this new welding technology would be perfect for a company which produces pre-fabricated panels and sells them to a furniture maker. It is also a technology which fits perfectly within the concept of Digitalisation 4.0, because you are able to control everything – there is a direct line of communication between the machinery and the operator, and no glue is required, meaning that it is a relatively easy process.

The butt joint gluing of cross laminated timber represents a revolution in the assembling of Cross laminated timber, but challenges remain. How, for instance, would you like to see future research address and improve rupture behaviour and on-site construction processes?

This is almost a natural evolution, in that the product needs to be incredibly robust as, typically, it is bonded on site. We therefore conduct extensive laboratory tests, and adhere to strict regulations. The dynamic tests include looking at how the products bend when they are assembled; long term testing includes tests on moisture, temperature resistance and load bearing resistance (we have to prove that any products including such a joint which are being used, for instance, in the structure of the third floor of a building will remain intact even if it is exposed to such external influences).

The limitation factor is the glue itself, and so we hope to get to the point where the glue is so well bonded that the wood breaks first; that would make it easier for companies to sell the technology. While this has already been considerably improved, there is still work to do to get to the point where we are able to compete with concrete.

Moving forwards, do you feel more needs to be done to raise awareness of the potential for wood products to replace other materials in the construction sector (and perhaps other areas) so as to move towards a more sustainable and environmentally-friendly future? And would you say that there is a lack of knowledge around what word-based technologies can actually achieve?

Yes, there is certainly a lack of knowledge, and so we are working to educate, in the first instance, architects. There is a sense that in many instances architects can perhaps be aware of the potential of wood, but only at a very low level, after which they look back to concrete or steel.

In our institute, we know the limit of the materials, and in order to help this dialogue progress we are therefore also exploring different combinations of materials – glass and wood, wood and concrete, and so on.

Wood also has significant potential to aid efforts towards an environmentally friendly circular economy because it can be recycled at the end of life its life.

Additionally, in a world of increasing urbanisation there is a stark decrease in the space available for construction. That is, in many cities buildings are extended upwards as there is less room to expand outwards, for instance. Furthermore, the fact that many city buildings are situated in close proximity to others means that it can also be difficult for heavy construction equipment such as cranes to gain access in order to undertake significant building works. As such, wood can also play a role here – it is a lightweight material which would therefore not require the use of such construction equipment but is nevertheless robust enough to increase the size of a tower or building.

There are barriers to this, however, and these include a lack of trust in the capabilities of gluing and welding technologies – which we can address by educating architects and engineers – and the fact that other materials such as steel and concrete remain more competitively priced.

One of the ways we are working to help accelerate the take-up of wood-based products is via the Wood Rise initiative, which aims to increase the use of wood-based products for multi-story buildings both across Europe and worldwide (Canada, for instance, is involved). This initiative is fostering a dialogue between architects and engineers; and from this – and from elsewhere – we are realising that there is a need for standardisation and simplification; we need to make sure that people can be made easily aware of both the products that are available and that these technologies have been rigorously tested and validated so that they can make informed decisions about which material works best for them in any given project.

In the future, both standardisation and a higher level of quality in pre-fabricated materials will be crucial. There has been talk of 3D printing houses out of concrete, and there is no reason why this could not also be achieved using wood-based products once some of the pre-fabrication challenges have been worked out.

Given these challenges – and indeed the huge potential that wood-based products can play across a range of sectors – where will you be focusing your future efforts?

We will be exploring solutions to the pre-fabrication challenges, of course, while we will also be investigating the full use of wood biomass not only in the construction sector, which is important, but in all sectors. We hope that wood will come to replace some petroleum-based plastics for insulating foam used in composites in the aerospace industry, for example. Indeed, this is an industry where wood in all its forms can be used.

In a more general sense, we hope to see the evolution of new business models for forest owners as those who manage or own older forests can benefit from side products, such as wood bark, while others will be able to sell their timber to for construction, and others still will be able to sell their wood to the paper industry, or for the creation of chipboard.
This is known as ‘the cascade use of materials’, and there are signs that an increasing number of people in the sector are starting to think in this way which, of course, is extremely positive, and which ties in well to our circular economy vision.

The European Commission is certainly heling here through, for instance, the many new Calls in Horizon 2020 dedicated to areas such as wood biomass, bio based composites, and the bio industry. In light of such progress, it is clear that now is the time for change, and as we move towards being able to compete with other materials, I am delighted to see some larger companies, who are now becoming aware of wood’s potential, are now starting to invest in these wood-based products. We just need to help that interest grow.

Professor Frederic Pichelin
Institute for Materials and Wood Technology
Bern University Of Applied Sciences
+41 32 344 03 42

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