Wool Fibers Improve Green Building Components

By Nidhi DhullReviewed by Susha Cheriyedath, M.Sc.Aug 13 2024

Could wool be the eco-friendly material of the future? A recent review article published in Case Studies in Construction Materials investigated the potential of using recycled wool fibers from sheep shearing waste in green building components.

This systematic literature review examined how these materials could be utilized in the construction sector and identified both their advantages and limitations. The study highlights the promise of recycled wool as a sustainable option for building materials, shedding light on its practical applications and the challenges that need to be addressed.

Background

The building sector has a significant environmental impact, primarily due to waste production and carbon emissions. To address this, there is growing interest in using natural materials to reduce reliance on non-renewable resources. Agricultural wastes and by-products are being explored as natural fibers in eco-friendly building components.

These "green" components are assessed based on a balance of material properties, recyclability, cost, and environmental impact. Despite numerous certifications aimed at ensuring the sustainability of building materials, truly sustainable options remain limited.

Natural fibers are increasingly recognized as an ideal eco-friendly alternative to traditional construction materials, offering excellent thermal and acoustic insulation. They can also serve as reinforcement in cement mortars, composite materials, bricks, and other building products.

This study specifically investigates the potential of wool fibers derived from sheep shearing waste in the green production of building components. The research focuses on how these recycled wool fibers can contribute to sustainable construction practices.

Natural Fibers for Green Building Components

Natural fibers were initially used in the construction sector back in 1974, but their practical application only began to take off after 2003. These fibers offer thermal insulation performance that rivals that of conventional plastics and inorganic materials, presenting a fully sustainable alternative to environmentally harmful plastics.

Natural fibers can be categorized based on their origin: organic fibers come from plants or animals, while inorganic fibers, such as asbestos, carbon, and glass, are derived from minerals. They are valued for their environmental compatibility, high availability, low cost, renewability, and biodegradability. Additionally, their thermal, mechanical, acoustic, and hydraulic properties can be economically tailored to meet specific construction needs.

Despite these benefits, the durability of natural fibers poses a challenge. They are sensitive to environmental factors such as temperature, sunlight, and humidity, which can significantly shorten their lifespan. Among natural fibers, those derived from animals, like wool, are particularly vulnerable due to their keratin content, compared to plant-based fibers, which are primarily composed of cellulose.

This study focused on wool fiber because managing this resource is becoming increasingly important from an environmental perspective. Wool is obtained from sheep fleece and consists of approximately 60 % keratin, 10 % fat, 10 % wool sweat, 15 % moisture, and about 5 % impurities. Its attributes—durability, hydrophilic/hydrophobic properties, thermal performance, and fire resistance—make it highly suitable for green building applications.

Wool Fibers in Green Building Components

Wool-based building components demonstrate excellent thermal and acoustic performance, often surpassing their mechanical attributes. Increasing the wool content in building composites enhances their thermal resistance due to the high porosity of wool fibers, which trap air and improve thermal efficiency. This performance is comparable to traditional insulation materials like glass wool, polystyrene, and cellulose.

Wool's hollow structure also makes it effective at sound absorption, particularly at mid and high frequencies. This characteristic improves acoustic performance with thicker wool-based materials, such as mats, mattresses, and non-woven fabrics, providing better sound wave dissipation and enhancing their acoustic absorption coefficient.

However, the mechanical performance of wool in building applications tends to be less favorable. While increasing wool reinforcement in materials like bricks and plaster can improve flexural strength, it often reduces compressive strength. This trend is also observed in cement and mortars reinforced with wool fibers. The decline in mechanical properties is largely due to wool’s porosity and hydrophilic nature, which requires more water to enhance the workability and compaction of the matrix.

To address these challenges, preliminary chemical treatments can be used to reduce wool's hydrophilicity and improve its adhesion to the matrix. Despite these mechanical limitations, the hygroscopic nature of wool fibers contributes positively to thermal and acoustic insulation, enhancing comfort and reducing the energy needed for heating and cooling. Overall, the thermal and acoustic performance of wool-based building components is comparable to conventional materials like fiberglass, polystyrene, and rock wool.

Conclusion and Future Prospects

Overall, the researchers provided a thorough analysis of how wool fibers affect the mechanical, thermal, and acoustic properties of building components. While wool fibers show great promise as an eco-friendly alternative to traditional materials, there are several areas needing improvement for their practical application.

To enhance the mechanical properties of wool-based components, improving fiber-matrix adhesion through chemical treatments to reduce wool's hydrophilicity is crucial. Additionally, developing novel technologies to minimize water usage during wool treatment could be beneficial.

The researchers recommend establishing a production scale for recycled wool fibers that aligns with market needs. They also suggest that further mechanical and physical testing of prototypes is essential to advance the use of wool fibers in new green building components. Applying life cycle assessment will help evaluate the sustainability of wool-based construction materials and ensure their viability in the building sector.

Journal Reference

Midolo, G., Zoppo, M. D., Porto, S. M. C., & Valenti, F. (2024). Recycling of wasted wool fibers from sheep shearing for green building components: A review. Case Studies in Construction Materials, 21, e03623. DOI: 10.1016/j.cscm.2024.e03623, https://www.sciencedirect.com/science/article/pii/S2214509524007745

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.