Investigation of impact sound behaviour in light weight floor constructions - A market survey and finite element analysis

Abstract: In the last years, the interest in high-rise timber framed building has gone up resulting in an increased demand for good solutions regarding sound insulation. Due to the worldwide growing interest in environmental issues, it has become of greater importance for companies to find ways to take care of their residue, instead of throwing it away. This can benefit both the environment, as less new material is used, and the economy, as less material goes to waste. Ecophon is presently developing a new type of lightweight aggregate (LWA) from glass wool residue that comes from their production of sound absorbing tiles. It will be investigated if these new LWA’s can be used as ballast in intermediate floors. The aim of this thesis is to find intermediate floor constructions where the new materials can be used. A market survey will provide the basis and suggest a few specific floor constructions where the LWA’s could replace other insulation materials. To further investigate the materials sound insulation properties in an actual floor, a FEM-calculation in Abaqus will be used. The FEM-modelling will be executed on a standard type floor to ease further comparison with other filling materials. The FEM-modelling will give the opportunity to compare the new materials with others that are commonly used in today’s market. The results from the FEM-calculation will also be compared to measurements done by the consulting company Akustikverkstan. Analyzing accelerations in the bottom plate for frequencies up to 125 Hz showed no significant improvement when adding LWA 1 into the floor. The accelerations decreased for some frequencies but then again got worse for others. To motivate an improvement, the accelerations would have to be lowered for all calculated frequencies. The most likely reason for the LWA's acoustic performance is its lack of stiffness which otherwise is the main reason to add mass. In this case, the mass is added without providing the necessary amount of stiffness. With the measurements of the laboratory room at Akustikverkstan, it was possible to recalculate the accelerations in the bottom plate of the Abaqus model into sound pressure levels. This made comparison possible and one could see a correlation between the measurements and the calculations. Possible applications for the material should be investigated further as the manufacturing process is cheap and energy efficient in comparison to other recycling methods for mineral wool residue. This is of interest for Ecophon, not only from an environmental point of view but also from an economical perspective.