Abstract

The objective of this research evaluates performances of waste recycling as an absorbent which are made of sewage sludge carbide, fly ash and bottom ash after testing of noise reduction. In order to measure sound absorption, an impedance tube was connected with two microphones. An absorption coefficient and noise reduction coefficient in the sound absorption were evaluated by transfer function method. The absorption characteristics of the specimen in an impedance tube were measured by 1/3 octave band (in 100 Hz ${\sim}$ 6,400 Hz). The particle sizes of the specimen were 1 mm, 2.8 mm and 4 mm per section. And thickness of the specimen were 10 mm, 20 mm, 30 mm, 40 mm and 50 mm. Also, The particle size distribution of specimen was observed by close-up photography. The results of evaluated absorption coefficients for sewage sludge carbide, fly ash and bottom ash were 0.406, 0.144 and 0.213 respectively. At the maximum peaks for the evaluated absorption of sewage sludge carbide, fly ash and bottom ash were 0.865 (4,978 Hz), 0.770 (4,210 Hz) and 0.672 (5,640 Hz) respectively. When comparison with glass wool of absorption coefficient of 0.399, the sewage sludge carbide was estimated possible absorbent for the waste recycling material.

Keywords

• Absorption coefficient;
• Absorbent;
• Bottom ash;
• Fly ash;
• Impedance tube;
• Sewage sludge carbide