A study led by researchers from the Gandia campus of the Universitat Politècnica de València (UPV) concludes that acoustic materials made from recycled and natural fibers can retain a large part of their performance even after more than 16 years of aging. The results reinforce the potential of these materials as an alternative for more sustainable construction.
The work, published in Case Studies in Construction Materials, analyzes the long-term evolution of 32 acoustic materials made from recycled polyester, textile waste, cotton, wool, hemp, jute, kenaf, or coconut fiber, among others. These materials are used to reduce reverberation and improve sound comfort in classrooms, offices, auditoriums, or homes, and can also contribute to acoustic insulation.
The samples analyzed, originally manufactured in 2009 as part of a European LIFE project, were stored for approximately 16 and a half years under uncontrolled indoor environmental conditions, subjected to variations in temperature and humidity and dust accumulation. These conditions allowed for the study of their response to prolonged aging similar to what many acoustic materials used in indoor spaces may experience.
The team re-analyzed the samples using the same procedures employed in 2009 and compared key parameters such as sound absorption and airflow resistivity. “The results show that, in general, the materials maintain a large part of their original acoustic properties after more than a decade and a half,” highlights Jesús Alba.
The study detects greater stability in predominantly synthetic materials. Those made with natural fibers or hybrid combinations showed greater sensitivity to aging, although they also retained notable acoustic behavior. Overall, the results confirm that both recycled and natural materials can maintain adequate acoustic absorption capacity over long periods.
The researchers completed the study with optical microscopy analyses to evaluate possible changes in the fiber structure, diameter, and porosity, and to better understand the physical transformations associated with natural aging. According to the UPV team, these results provide useful data for architects, engineering professionals, and manufacturers, and reduce uncertainty about the durability of recycled and natural materials for building acoustic conditioning.
