Acoustic behaviour of GFRP-PUR web-core composite sandwich panels

This paper presents an experimental and analytical study about the sound insulation of innovative sandwich panels - named EasyFloor - for the rehabilitation of degraded timber floors in old buildings. Two types of panels were developed: (i) an all -composite sandwich panel, made of glass fibre reinforced polymer (GFRP) face sheets and webs, and polyurethane (PUR) foam; (ii) and a hybrid sandwich panel, where the top face sheet comprises a thin layer of concrete. The study included the comparative analysis of the airborne sound reduction and impact sound pressure level of both types of panels based on experimental tests on full-scale specimens, including a typical floor covering. The acoustic insulation properties determined experimentally were compared with predictions from different analytical models typically applied to sandwich panels, and also with performance requirements defined in building regulation. Among the different analytical models that were assessed, Sharp ' s model provided the most accurate predictions when considering the natural and dilatation frequencies as the critical frequency. The comparison of the normalized airborne and impact sound indices determined experimentally with requirements set in building regulation shows that the use of GFRP-PUR panels in the rehabilitation of lightweight timber floors and in new construction, where building comfort requirements are stricter, require mitigation measures to improve sound insulation.