Sustainable acoustic treatment using agricultural waste valorization through eco-friendly pomegranate peel-clay...

Achieving an acoustically suitable learning environment presents a significant economic challenge, particularly in developing countries. This study investigates an eco-friendly clay-based acoustic brick incorporating agricultural waste, specifically pomegranate peel (PMPE), to develop an acoustically enhanced material suitable for educational and similar spaces. Laboratory experiments were conducted on ten specimens with two thicknesses (30 and 50 mm) and PMPE contents ranging from 5% to 25% at 5% intervals. Sound absorption coefficients were measured using a Brüel & Kjær (B&K) Type 4206 two-microphone impedance tube. Results demonstrated that increased PMPE content generally enhanced sound absorption across most frequency ranges. The 50 mm thick specimens achieved a maximum weighted sound absorption coefficient α_w of 0.65, compared with 0.55 for the 30 mm thick specimens. Increasing specimen thickness shifted sound absorption toward lower frequencies. In the high-frequency range (>2000 Hz), the 50 mm thick specimen containing 25% PMPE achieved the highest mean absorption coefficient in this range of 0.73 and an estimated Noise Reduction Coefficient (eNRC) of 0.60. The improved acoustic performance is attributed to the increased porosity generated by the burnout of organic waste during firing, which enhances sound energy dissipation within the material structure.