Acoustic underlay manufactured from carpet tile wastes. Part 1: Effect of variation in granular/fibre dry ratio, binder concentration, and waste particle size on impact sound insulation of the produced underlays

Carpet waste is of growing concern both to environmentalists and manufacturers pressured by increasing costs of landfill dumping. The challenge for carpet producers is to find ways of minimising their waste or find alternative uses for their unwanted by-products. This paper builds on an earlier study (Taylor, A.: 'Novel underlays from carpet waste', Ph.D. thesis, Bolton Institute, U.K., 2004) where carpet tile wastes have been successfully used to produce underlays for domestic as well as commercial markets. To add value, the acoustic behaviour of these underlays, where granular/fibre mixing ratios, binder concentration and particle size distribution play a major role, has been examined in this study. The results show that it is possible to maximise the impact sound insulation capabilities of these underlays by selective control and adjustment of the above variables. Manufacturing formulation consisting of 60:40 granular/fibre mixture ratio, 60% binder concentration and granule particle size dimensions of <2mm is shown to be most appropriate in achieving effective impact sound insulation.