Bio-based Fire-Resistant Materials: A Revolution in Sustainable Construction
Each year, millions of buildings worldwide are affected by fires, resulting in significant human and economic losses. In the United States [1], structural fires account for an average of more than 380,000 residential and non-residential fires annually, causing direct losses exceeding $14 billion. In light of this growing threat, fire safety has become an absolute priority in the construction sector. Simultaneously, the demand for more sustainable and environmentally friendly buildings continues to rise. Wood, a renewable natural material with a low carbon footprint, appears to be an ideal solution to address these challenges. However, its combustibility, although manageable with specific treatments, is often perceived as a major barrier to its widespread use in construction.
This perception is evolving thanks to technological advancements. Recent studies [2] have demonstrated that bio-based materials, such as wood, can be made as fire-resistant as traditional materials through specific treatments. This comprehensive research provides a state-of-the-art overview of the different approaches to fireproof bio-based materials, thereby opening up new opportunities for more sustainable and safer construction.
In this article, we aim to demonstrate that fire-resistant bio-based materials are a viable and sustainable alternative to conventional building materials.
Bio-based Materials: A Sustainable Alternative for Construction
Definition and Advantages of Bio-based Materials
Bio-based materials, derived from biomass, are a promising alternative to traditional construction materials due to their reduced environmental impact and notable properties. Sourced from renewable organic matter such as wood, hemp, and straw, these materials offer numerous advantages. Primarily, their production generates significantly fewer greenhouse gas emissions compared to conventional materials, contributing to efforts to mitigate climate change [3]. Additionally, their renewable nature reduces dependency on finite fossil resources and supports the principles of a circular economy.
Moreover, bio-based materials enhance indoor air quality by controlling humidity and minimizing the release of volatile organic compounds (VOCs), which are known to cause health problems [4]. Their natural insulating properties also provide superior thermal and acoustic comfort. For example, wood wool exhibits excellent thermal insulation, helping to reduce heating and cooling demands [5].
Another key strength of bio-based materials is their versatility. Beyond wood, commonly used in construction, a variety of options exist, including plant-based insulation (hemp, flax, cellulose), particle boards derived from wood or plants, and lime-based plasters for finishing. This broad range of materials makes them suitable for both new construction projects and renovations.
Treatments for Bio-based Materials: A Necessity for Optimal Use
While bio-based materials offer significant environmental and aesthetic benefits, their use in construction often requires specific treatments to address their organic nature. These materials are prone to degradation from factors such as moisture, wood-boring insects, and fire. Treatments are therefore essential to enhance their durability, safety, and overall performance.
Fire-retardant treatments are among the most critical interventions. They work to reduce the material’s flammability and slow the spread of fire. For instance, studies have shown that borate treatments for wood significantly decrease ignition temperatures and limit smoke production [6]. Hydrophobic treatments, on the other hand, protect bio-based materials from moisture, reducing the risk of mold and fungi growth that could compromise structural integrity. Insecticidal treatments are also commonly applied to prevent infestations by termites and other wood-boring insects, which can weaken wooden elements [7].
The choice of treatment depends on factors such as the type of bio-based material, its intended application, and regulatory requirements. It is crucial to select treatments that ensure maximum efficiency while being environmentally friendly and safe for human health. Increasingly, natural treatments based on vegetable oils or mineral salts are being adopted for their low environmental impact and sustainability [8].
Fire-Resistant Treatments: An Effective Solution for Protecting Bio-Based Materials
To ensure fire safety in buildings using bio-based materials, fire-resistant treatments are essential. These treatments aim to reduce the combustibility of materials, slow the spread of flames, and limit the production of toxic smoke.
Types of Fire-Resistant Treatments
There are various fire-resistant treatments, each with specific characteristics and mechanisms of action. Intumescent treatments, for example, form a protective charred layer in the event of a fire, slowing the spread of flames and protecting the underlying material [9]. Chemical treatments, on the other hand, alter the chemical properties of the material, making it less prone to combustion. These can be based on mineral compounds (borates, phosphates) or organic compounds (phosphates, halogens) [10]. Increasingly, combinations of treatments are being used to optimize performance and meet the specific requirements of each application.
Mechanisms of Action
Fire-resistant treatments work in different ways to reduce the combustibility of materials. Some absorb heat, others dilute volatile combustibles, or release flame-inhibiting gases. For example, intumescent treatments create an insulating layer that slows heat transfer to the underlying material, while chemical treatments can release non-flammable gases that dilute combustibles and inhibit the combustion chain reaction.
Standards and Certifications
To ensure the quality and effectiveness of fire-resistant treatments, several standards and certifications have been established. In Europe, the EN 13501-1 standard defines the fire reaction classes of construction products, including treated materials. Fire-resistant products must also meet specific health and environmental requirements, particularly concerning the emission of hazardous substances.
Why Choose Fire-Resistant Bio-Based Materials?
When properly treated, bio-based materials offer a unique combination of fire safety, comfort, and sustainability while aligning with circular economy principles.
Fire Safety: Comparable or Even Superior Performance
Contrary to popular belief, fire-resistant bio-based materials can achieve levels of fire safety comparable to, or even exceeding, traditional materials. With appropriate treatments, it is possible to significantly reduce their combustibility, flame spread rate, and the release of toxic smoke. Numerous studies have shown that materials such as treated solid wood or fire-resistant wood fiber panels can meet the strictest fire safety standards [11].
Comfort and Health: An Enhanced Living Environment
Fire-resistant bio-based materials also provide notable advantages in terms of comfort and health. Their natural insulating properties help improve the thermal comfort of buildings, reducing the need for heating and cooling. Additionally, some bio-based materials have excellent sound absorption properties, creating quieter and more restful environments. Finally, these materials are often associated with improved indoor air quality, as they emit fewer volatile organic compounds (VOCs) than traditional materials.
Circular Economy: A Sustainable Approach
The use of bio-based materials aligns seamlessly with the principles of a circular economy. These materials are derived from renewable resources and help reduce dependence on fossil-based resources. Moreover, their local production promotes short supply chains and lowers the carbon footprint associated with transportation. At the end of their life cycle, bio-based materials can often be composted, converted into biogas, or used for energy recovery, minimizing waste generation.
Case Studies and Future Perspectives
Case Study: Fire Performance of Wood Particleboards Treated with Bio-Based Flame Retardants [12]
This study evaluated the effectiveness of bio-based flame retardants applied to wood particleboards. The objective was to compare the fire performance of boards treated with flame retardants based on phytic acid and chitosan against untreated boards.
Methodology
Researchers impregnated wood particleboards with solutions of chitosan and phytic acid, forming a flame-retardant complex. Combustion tests were then conducted to evaluate the fire resistance of the treated and untreated samples.
Results
Treated boards exhibited a significant reduction in combustion rate and heat release. Furthermore, the formation of a protective charred layer was observed, effectively limiting flame spread. These findings indicate that bio-based flame retardants can enhance the fire performance of wood-based materials while being more environmentally friendly than traditional chemical retardants.
Challenges and Future Perspectives
Fire-resistant bio-based materials, while innovative, still face several challenges hindering their widespread adoption. First, the production costs associated with bio-based flame retardant treatments remain high, limiting their accessibility, particularly for projects with significant budget constraints. Second, variations in fire safety regulations across regions complicate their certification and implementation. Finally, ensuring the long-term durability of fire-resistant properties without compromising material integrity presents a critical challenge, especially for constructions exposed to diverse climatic conditions or wear over time.
To overcome these challenges, several future-oriented strategies can be considered. Investment in research and development is crucial to lower production costs and enhance the efficiency of bio-based flame retardant treatments. Furthermore, harmonizing fire safety regulations at the international level could simplify their adoption and bolster their credibility among construction professionals. Lastly, raising awareness among stakeholders—such as developers, architects, and contractors—about the numerous benefits of fire-resistant bio-based materials can accelerate their integration into standard construction practices.
By addressing these challenges, fire-resistant bio-based materials have the potential to revolutionize the construction sector, combining sustainability, safety, and environmental responsibility.
Conclusion
Fire-resistant bio-based materials represent a significant advancement in sustainable construction, combining safety, comfort, and environmental responsibility. Real-world examples of successful buildings illustrate their potential to meet the strictest safety standards while offering aesthetically pleasing and environmentally friendly solutions. However, to drive widespread adoption, it is essential to address current challenges related to costs, regulations, and availability.
The future of sustainable construction depends on innovation and collaboration between public and private sectors to integrate these materials into diverse projects. By investing in research and supporting initiatives that promote their use, we can transform how we build, creating safer, healthier, and more sustainable structures.
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[1] National Fire Protection Association (NFPA). (2023). Fire statistics: Fires by property type. Retrieved from https://www.nfpa.org/News-and-Research/Data-research-and-tools/US-Fire-Problem/Fires-by-property-type
[2] Yang, Y., Liu, Y., Liu, S., & Zhang, J. (2021). Bio-based materials for fire-retardant application in construction products: A review. Journal of Thermal Analysis and Calorimetry, 144(3), 1217–1235. https://doi.org/10.1007/s10973-020-10238-1
[3] Cabeza, L. F., et al. (2021). Life cycle assessment (LCA) and carbon footprint of building materials: A comparison between biosourced and traditional materials. Renewable and Sustainable Energy Reviews, 151, 111467. https://doi.org/10.1016/j.rser.2021.111467
[4] Wargocki, P., & Seppänen, O. (2020). Indoor air quality and its effects on health and performance in office environments. Scandinavian Journal of Work, Environment & Health, 46(6), 432–447. https://doi.org/10.5271/sjweh.3923
[5] Prieur, N., & Blouet, E. (2022). Thermal insulation properties of bio-based materials: A study on wood wool. Journal of Building Engineering, 54, 104561. https://doi.org/10.1016/j.jobe.2021.104561
[6] Gao, Z., Wang, X., & Zhang, Y. (2016). Flame retardant properties of wood treated with chitosan–phytic acid. Carbohydrate Polymers, 151, 1270–1275. https://doi.org/10.1016/j.carbpol.2016.06.060
[7] Moraes, P. D., et al. (2023). Insect-resistant treatments for bio-based materials: Efficacy and environmental impacts. Construction and Building Materials, 364, 129908. https://doi.org/10.1016/j.conbuildmat.2023.129908
[8] Nguyen, T., et al. (2022). Natural flame retardants for bio-based construction materials: Properties and performance. Journal of Cleaner Production, 370, 133453. https://doi.org/10.1016/j.jclepro.2022.133453
[9] Shamsuri, A. A., et al. (2022). Intumescent coatings for fire protection of bio-based materials: Advances and challenges. Coatings, 12(3), 345. https://doi.org/10.3390/coatings12030345
[10] Zhanga, Q., et al. (2023). Chemical flame retardants in construction materials: Comparative analysis and health implications. Environmental Science & Technology, 57(4), 567–576. https://doi.org/10.1021/acs.est.2c01267
[11] Kandola, B. K., et al. (2021). Performance of flame-retardant bio-composites in fire resistance tests. Polymer Degradation and Stability, 186, 109534. https://doi.org/10.1016/j.polymdegradstab.2021.109534
[12] Gao, Z., Wang, X., & Zhang, Y. (2016). Flame retardant properties of wood treated with chitosan–phytic acid. Carbohydrate Polymers, 151, 1270–1275. https://doi.org/10.1016/j.carbpol.2016.06.060
Written by Mehdi BELAHOUCINE
