Survey on the acoustical properties of new sustainable materials for noise control

According to the definition of sustainability (Sustainable development meets the needs of the present without compromising the ability of future generations to meet their own needs ), a product can be considered sustainable if its production enables the resources from which it was made to continue to be available for future generations. A sustainable product can thus be created repeatedly without generating negative environmental effects, without causing waste-products to accumulate as pollution, and without compromising the wellbeing of workers or communities. In the last years many new materials for noise control have been studied and developed as alternatives to the traditional ones (glass or rock wool); these materials are either natural (cotton, cellulose, hemp, wool, clay, etc) or recycled (rubber, plastic, carpet, cork, etc.). Various methodologies have been proposed to evaluate the sustainability of materials and products (LCA, ECOINVENT; ECOPROFILES). The paper presents an updated survey of acoustical properties of sustainable materials and in particular sound absorption coefficient, airborne and impact sound insulation data, as well as an analysis of the procedures to asses the sustainability of these materials. Several sustainable materials have also been tested by the Author at the Acoustic laboratory of the University of Perugia: among these expanded clay granulates, kenaf, recycled polyester panels, re-cycled plastic, absorbing foams obtained from urban waste. Researches in this field received a boost thanks to the collaboration with the University of Bradford (UK): sustainable acoustic materials, especially from used tyres and carpets, were produced with good properties as far as impact sound insulation. The paper presents and discusses all the experimental data and draws come considerations and conclusions on future perspectives for sustainable materials for noise control.