Impact of Density and Porosity on the Sound Absorption of Binder-Free Aggregated Rice Husk

Abstract

This study explores the use of binder-free rice-husk aggregates, a widely available agricultural byproduct, as a sustainable alternative for sound absorption in building applications. We assessed the material’s efficacy by conducting experiments using cylindrical housings that were filled with rice husk aggregate. The aggregates were then tested in an impedance tube according to the ASTM E1050 standards in the frequency range of 400 to 6,000 Hz. The porosity was measured using an air pycnometer. The resulting average sound absorption coefficient (αavg) was modeled in terms of the porosity and the density with quadratic equations. Thus, if either property is known, αavg can be predicted. The highest recorded value of αavg was 0.81. This study underscores the environmental and practical advantages of using binder-free rice husk, especially given its local availability and the absence of binders. The findings also open avenues for sustainable construction materials and could contribute to eco-friendly noise-control applications.