Sound Absorption of Recycled Gypsum Matrix Composites with Residual Cellulosic Pulp and Expanded Polystyrene

This work aimed to study the technical feasibility of using industrial gypsum, expanded polystyrene (EPS), and cellulose solid wastes in the production of acoustic insulation panels for buildings. Five traces of acrylic gypsum matrix were produced with variations in the proportions of cellulosic pulp and EPS and always maintaining the same proportion of recycled gypsum and water. The composites produced were tested according to the ISO 10534-2 (2015) standard for the determination of the coefficient of sound absorption and ABNT NBR 14715-2 (2010) for bending tests. The results didn't show statistically significant differences in the coefficient of sound absorption with variations in the quantities of each material. However, the sonic frequency of the tests directly influenced the results, presenting a better performance at a low frequency (250 Hz). The results qualify the composite produced for use as acoustic insulation and can be used in plates for sound reflection in buildings in places where it doesn't require resistance to great stresses.