Acoustic composite panels based on recycled paper sludge

Abstract

Recent trends in waste management have initiated interest in recycled materials for sound absorption applications. The present paper studies the possibility of paper sludge to be recycled as material for sound absorption applications. Paper sludge (PS) is the water treatment waste, produced during paper production. In this study we consider three different binding materials slaked lime, clay and cement. The aim of the study was to characterize sound absorption properties the mentioned composite materials, which was used with different ratios between PS and the binder. In this study we present the method of such sample making. The created composites was made with at least 50% PS in the composite. The sound absorption tests were done using impedance tube, two microphone technique, according ISO 10534-2 standard. The results showed that different binding materials effect the sound absorption of the material differently. The highest sound absorption coefficient values were gained using cement as binder, however subjectively was noticed that it was considerably more fragile compared to other tested composite materials. The tested sample thickness was 10±2 mm. In higher frequency range the sound absorption sound absorption coefficient reached up to 0.91, but in lower frequency range the results were considerably lower due to small thickness. The results show the possible way to recycle the paper sludge.