Published on 14 April 2025
Wood shows surprising and widespread promise, far beyond the field of construction. Five researchers from IMT Mines Alès have been focusing their work on this multifaceted material, and the questions raised when considering its use, both in terms of performance and durability.
An ancestral material with modern applications, wood is a key player in the ecological transition. Between sustainability, recycling and innovation, it demonstrates a surprisingly wide-ranging potential, well beyond construction. Credits: Unsplash.
Wood has been used as a building material for thousands of years, and is currently experiencing renewed popularity. This traditional material is environmentally friendly and sustainable, and there is a growing interest in using wood in a context of environmental transition. It is much more than just a material for building homes, as it has also shown promise for engineering highly technical products, such as satellites.
According to Stéphane Corn, research professor at the IMT Mines Alès Materials Center (C2MA), “wood is a complex material that has been used since the dawn of time, but that continues to surprise us by the sheer diversity of its applications”. There are several researchers at the center who are exploring new ways of adding value to this natural resource, by studying its potentials on different scales, from solid frames made to wood fiber and chipboard. Their expertise comes together in a great number of projects, across various disciplines.
One of the main challenges in using wood as an engineering material is its durability and ability to meet modern technical performance requirements. As part of the Durability of Eco-Materials and Structures (DMS) team, Stéphane Corn is developing methods of characterizing and modeling the mechanical properties of a range of materials in different uses. In direct partnership with the research teams from the Mechanics and Civil Engineering Laboratory (LMGC) and CIRAD in Montpellier, he is testing various types of wood.
The materials mechanics researcher conducts conventional static tests which involve applying force to samples of wood to measure resistance and rigidity. He also carries out vibration analyses. “By sending a slight vibration through a sample of the material, we measure its resonance frequencies, from which we can identify, without damaging it, its three-dimensional rigidity and its ability to absorb vibrations”, he explains. This is crucial for the stability of structures exposed to vibrations, whether due to natural causes (seismic activity, etc.) or more everyday human activities (construction work nearby, machine operation, etc.). “These analysis methods, generally applied to the monitoring and predictive modeling of building and structural behavior, also enable the non-destructive characterization of materials in the laboratory”, he adds.
In addition to its mechanical performance, wood also has to prove itself when it comes to another essential property of building materials, which is fire resistance. “Many bio-based materials are sensitive to a phenomenon that has not been widely studied and is rather difficult to detect: smoldering fire, i.e. the slow, flameless combustion of materials”, explains Rodolphe Sonnier. This researcher in the Polymers, Composites and Hybrids (PCH) team takes a particular interest in the fireproofing of wood. “We’re looking to demonstrate that, depending on the tree species or the part of the wood used, such as the bark or heartwood, reactions to fire can vary. Some types of wood are naturally more fire-resistant, and we are also exploring bio-based treatments, using natural resins or flame retardants, to improve this property”, he explains.
After several stages of fractionation and preparation (top, left to right), agroforestry wood can then be used to produce biosourced composite materials (bottom). Credits: IMT Mines Alès, Agroof.
Of the various forms of wood, fibers are often the focus of C2MA’s research, as a great deal of work is dedicated to the development and characterization of wood fibers for use in composite materials. IMT Mines Alès has longstanding expertise in the study of reinforcing fibers. Research was initially focused on synthetic materials, and has gradually turned towards more environmentally friendly solutions. “That’s how we moved from glass fibers to plant fibers and, over the years, to wood fibers,” explains Stéphane Corn.
While the majority of the wood samples at macroscopic scale come from the xylotheque at Cirad, so-called ‘divided’ samples come from the FRD-Lab technology hall: the first European platform devoted to the extraction and characterization of plant-based fibers, aggregates and semi-finished products, and a partner of IMT Mines Alès for over 10 years on research projects. Obtaining wood fibers is a complex process, requiring either grinding and sieving to obtain fibrous residues of controlled dimensions, or a specific grinding process – or steam explosion – which uses mechanical pressure to produce high-density monofibers.
These fibers are then characterized and selected to be used as fillers or reinforcement materials in composite products. Within the PCH team, research professors Clément Lacoste and Nicolas Le Moigne are looking into the properties of these wood fibers, how they can be integrated into composite materials, and the final properties of these materials. In combining dimensional, physicochemical and mechanical analyses, the aim of their work is to develop plant-based fibers that can be used as alternatives to synthetic fibers, to make projects more eco-friendly while still delivering high-performance. The AGROBRANCHE project, financed by ADEME, is an example of this.
VOC emissions: a far cry from woody scents
Wood is not the only factor to assess in analyzing the durability of these composite materials such as chipboard, and scientists are also studying the other materials and binders used. “One of the issues with wood-based panels in engineering, for instance, is the use of glues that contain formaldehyde”, points out Clément Lacoste. Over time and as the synthetic glues and resins wear, these wooden panels can begin to emit Volatile Organic Compounds (VOC), which are detrimental to the quality of indoor air, and even carcinogenic, such as formaldehyde.
In an attempt to reduce these health risks, the researcher is working on developing bio-adhesives using polymer resins of natural origin. He is also working with the research team on interactions of wood with its environment (RIME). “We are assessing the indoor air quality in buildings to identify sources of pollutants and find solutions to reduce emissions”, explains Valérie Desauziers, professor and head of the RIME team. “This includes studying solid wood as well as composite materials and chipboard, and so covering construction materials, decoration and furnishings. Our research is therefore cross-disciplinary and complementary to the work done by the PCH and DMS teams”, she adds.
For these studies, the researcher bases her work on conventional air analysis and emission testing methods, but has also developed in-situ measurement methods with her team, to identify pollutant source materials in a building. “There are two approaches: targeted analyses, to detect known and/or regulated pollutants, such as formaldehyde, and non-targeted analyses for emerging compounds,” she specifies. “We know that, faced with increasingly stringent regulations, construction firms are looking into new materials. We are therefore developing new methodologies to identify and quantify new additives, as well as unintentionally added substances, whose impact on health is still little or poorly understood.”
This study of emissions linked to aging wood materials is a part of the Life-Cycle Assessment (LCA) for these materials. The RIME team therefore studies each stage of the life cycle of the wood materials from the manufacturing phase to assess their environmental footprint. As Nicolas Le Moigne explains: “The use of wood in material applications calls for reflection on the management and optimal use of resources – are they from natural forests or managed by human activity? Which tree species? – and for the parts that have been reused or can be reused – are residues used? timber? What are their specific features and advantages in relation to the intended application?”
The development of biosourced and biodegradable adhesives has led to new wood products, such as this panel made exclusively from local forest products (maritime pine). Credits: Clément Lacoste.
In this life-cycle assessment, there is a special focus on reuse and end of life, especially in light of recent regulations such as the AGEC Act on the management of waste from the construction industry. For example, Clément Lacoste and Stéphane Corn are working with Didier Perrin, who is also a researcher at IMT Mines Alès, on a project with eco-organization Valdelia to assess residual mechanical properties and as such, the recyclability of second-hand furniture. Valérie Desauziers points out that in order to reuse these materials, it is necessary to ensure that they do not emit any harmful substances, as is the case for old timber products that were treated using biocides that are no longer permitted today.
In light of these assessments, research conducted on wood-based materials and products takes on its full meaning. In assessing the environmental impact of wood-based materials – particularly chipboard which is widely used – throughout the entire life cycle, scientists hope to encourage the construction industry to opt for non-toxic, more environmentally friendly solutions, with less synthetic compounds that are difficult to recycle.
As well as highlighting the challenges related to using wood-based materials, this research also reveals their many qualities and great potential. “Due to its natural diversity, wood is pretty much an endless source of research, and the progress made in terms of knowledge allows its properties to be put to better use!” says Stéphane Corn.
The more recent development of wood nanocelluloses from high-performance and lightweight wood is an example of this, and it opens the door to potential applications in a wide range of industrial sectors, including the packaging, optoelectronics, automobile, aeronautics and biomedical sectors. In making use of all the properties of wood in all its forms, together with their academic and industrial partners, the research teams from IMT Mines Alès are proving that wood is not just a traditional material, it is a material of the future, ready to meet the challenges in terms of engineering and sustainable construction.
Wood can also be used for local initiatives that aim to develop materials that are more respectful of the environment for green building. The PANTHER2Guyane (Thermal Panels made using recycled wood residues in French Guiana) project, led by UMR EcoFoG, devoted to forest ecology in French Guiana, is a specific example. This French National Research Agency project aims to produce thermal insulation panels for homes in French Guiana using by-products from the local wood sector. “The idea is to set up a manufacturing process that uses local species, fast growing wood or sawmill by-products, and that focuses on the link between the specific features of the wood and the properties of the final panels”, explains Nicolas Le Moigne. “This is a typical example of an ethical project, both in terms of the intended application and the short distance traveled between the resources and the panels manufacture, and therefore the environmental impact of the finished products.”
As proof of the current enthusiasm surrounding wood products, the IMT seminar, Working towards sustainable wood-based products with high environmental performance was held on 26 September last year at IMT Mines Alès in hybrid format. A number of academic organizations (CIRAD, ECOFOG, LMGC, IMT Mines Alès, Mines Albi), technical (FCBA) and industrial centers working in this sector (VALDELIA, XYLAE, WOODOO) were involved, and presented the recent developments on this topic, paving the way for proposed actions (chair, collaborative project, etc.).
