By Nidhi DhullReviewed by Susha Cheriyedath, M.Sc.May 12 2024Wood is a readily available and adaptable building material that can be utilized in various building parts and has been a fundamental component of infrastructures since ancient times.1 Its flexibility and sustainability have gained significant attention to mitigate the environmental impact of the resource-intensive construction sector.2
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Given the increasing incidents of illegal logging, there is an urgent need to develop sustainable alternatives to hardwood for construction purposes. Natural hardwood often has limited uses because of issues such as size constraints and defects like knots and cracks. Engineered wood products (EWPs), on the other hand, are viewed as environmentally friendly and are highly adaptable for construction due to their innovative designs.1 This article examines different sources of sustainable hardwood alternatives, highlighting their benefits, applications, and the challenges they pose in the construction industry
Sources of Sustainable Hardwood Alternatives
Hardwood alternatives such as EWPs are fabricated efficiently from renewable resources in various sizes and measurements. Different types of EWPs are employed in construction, including sawn wood-based glued-laminated lumber (glulam) and cross-laminated timber (CLT), veneer-based plywood, and laminated veneer lumber (LVL), strand-based oriented strand board (OSB) and laminated strand lumber (LSL), finger-jointed lumber, and wood I-beam.1,2
Sustainable EWPs are produced by bonding both soft and hardwood chips, pieces, or veneers with structural resins and by mechanically securing timber segments and beams.1,2 These raw materials can be sourced from plantations that cultivate fast-growing hardwood species like poplar, which are environmentally adaptable and have a rapid growth rate and short rotation period, making them ideal for green construction.
Other natural hardwood sources include white ash, yellow birch, white oak, eucalyptus, beech, chestnut, and teak.2
Applications in Construction
Advances in adhesive technologies and glue-lamination techniques have addressed the inherent dimensional and behavioral limitations of solid wood, expanding its use in structural applications within the building and construction industry.2 EWPs derived from solid wood now provide alternatives for hardwood in applications such as rooftop and floor coverings, solid structures, beams, and boat hulls.1
Specifically, glulam is generally employed as beams in lintels, floors, roofs, and purlins while CLT boards are suitable for heavy frameworks and multistorey structures due to high strength. They are used in flooring, load-bearing walls, and shear walls.
Alternatively, LVL, a composite of multiple veneer layers, offers high pillar strengths and is used in load-carrying beams in over-windows, entryways, and roof/floor frameworks. Furthermore, wood I-beams, available up to 80 feet long, help economically realize structures with high rigidity and heat insulation.1
Overall, these hardwood alternatives can be engineered as fit-for-purpose in infrastructure complying with performance requirements of stability, fire insulation, earthquake resilience, high rise, energy consumption, etc.2
Advantages
As a building material, EWPs offer multiple advantages, including dimensional stability, fabrication of large and complex structures, homogeneous mechanical properties, and minimal influence of common imperfections like knots. Additionally, they reduce the project cost while improving its construction speed, adaptability to seismic shocks, and energy efficiency.1
EWPs help realize the concept of green buildings, causing no harm to the ecosystem. These sustainable structural materials can play a significant role in a naturally concerned world. By using merchantable and non-merchantable wood pieces, they produce almost no waste.1
Additionally, they make efficient use of forest resources such as fiber, which is generally burned or abandoned to decompose, and previously underutilized hardwood species with small-diameter, low-quality logs. Thus, hardwood alternatives sourced from forest residues and plantations reduce the forest harvesting pressures.2
EWPs are designed to directly substitute conventional solid-sawn wood components in several applications. They offer an enhanced strength-to-stiffness ratio as well as sustainability using bioenergy. For example, CLT is five times lighter than concrete but exhibits a similar strength-per-weight ratio. Additionally, it is design-flexible and environmentally friendly, outperforming concrete in energy consumption, air pollution, and water contamination.2
Navigating Challenges
The development of sustainable hardwood alternatives is still primarily confined to laboratory settings due to several challenges in scaling up their production and integrating them into construction projects.3 A significant obstacle is the rapid dulling of cutting tools, which results from the high material density and extended pressing times needed to accommodate variable moisture content and lumber dimensions.2
Enhancing the stability and reliability of EWPs necessitates careful consideration of the hydrophilicity and biodegradability of the materials used. Furthermore, achieving uniformity in large-scale production is problematic, as the diffusion of chemicals into large-dimension wood specimens is hindered by factors such as size, porosity, and surface chemistry.3
Despite being sourced from sustainable avenues, creating truly green hardwood alternatives remains a challenge. The prevalent chemical modification methods for EWPs require substantial quantities of chemicals, electricity, and water, and they produce significant amounts of wastewater and harmful gases, contributing to environmental degradation.3
To fully capitalize on the potential of sustainable hardwood alternatives, a deep understanding of their structural properties, such as water stability, corrosion resistance, and antifungal capabilities, is essential. Continuous innovation in processing technologies is crucial to address these ongoing challenges.3
Latest Developments
Novel materials and methods are being employed in the search for sustainable hardwood alternatives. For instance, a recently published book Bamboo - Recent Development and Application reviewed the advances in bamboo composites for structural applications. Apart from being the fastest-growing plant on the Earth, bamboo is a renewable, lightweight, and adaptable resource with high physical similarities with genuine hardwoods.
The bamboo-based composites have immense potential as a substitute for wood, meeting hardwood requirements that are currently fulfilled by cutting trees or importing timber. They are applied in housing and construction sectors in the form of standard beams, planks, lumbers, truss elements, etc.4
Another recent article published in SSRN-Elseveir has suggested the integration of generative artificial intelligence (AI), such as Chat generative pre-trained transformer (GPT) or Bard, to enhance the performance of sustainable construction materials, including hardwood alternatives. Generative AI provides information on the latest innovations in processing alternatives like bamboo and its diverse applications in construction. Additionally, it helps evaluate the contribution of these materials to achieving the United Nations Sustainable Development Goals.5
Future Prospects
Looking ahead, expanding the use of proposed hardwood alternatives in the construction sector will enhance sustainability and decrease greenhouse gas emissions within the industry. The use of EWPs in essential building applications, whether for new constructions or renovations, can pave the way for a new generation of infrastructure characterized by zero waste and a positive environmental impact. These products boast improved mechanical performance, better thermal insulation, and increased seismic stability, promising a more sustainable and resilient future in construction.2
However, additional efforts are required to bridge the gap between high-performance hardwood alternatives and their scalable, sustainable applications in the future. These materials need to strike a balance between functionality, cost, service life, and scalability to succeed in the construction sector. Government incentives aimed at encouraging the use of EWPs to replace petroleum-based and energy-intensive materials in buildings could further promote their adoption, enhancing market penetration and contributing to a carbon-neutral future.3
References and Further Reading
1. Yadav, R., & Kumar, J. (2022). Engineered Wood Products as a Sustainable Construction Material: A Review. Engineered Wood Products for Construction. https://doi.org/10.5772/intechopen.99597
2. Acker, J. V. (2021). Opportunities and challenges for hardwood-based engineered wood products. 9th Hardwood Proceedings Part II. University of Sopron Press. ISBN: 978-963-334-399-9
3. He, S., Zhao, X., Wang, E. Q., Chen, G. S., Chen, P. Y., & Hu, L. (2023). Engineered wood: sustainable technologies and applications. Annual Review of Materials Research, 53, 195-223. https://doi.org/10.1146/annurev-matsci-010622-105440
4. Mili, M., Singhwane, A., Hada, V., Naik, A., Nair, P., Srivastava, A. K., & Verma, S. (2023). Advances in Bamboo Composites for Structural Applications: A Review. In Bamboo - Recent Development and Application. IntechOpen. https://doi.org/10.5772/intechopen.110489
5. Rane, N., Choudhary, S., & Rane, J. (2024). Enhancing Sustainable Construction Materials Through the Integration of Generative Artificial Intelligence, such as ChatGPT or Bard. SSR-Elsevier. http://dx.doi.org/10.2139/ssrn.4681678
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