Sound absorption capability and mechanical properties of a composite rice hull and sawdust board

Rice hull-sawdust composite boards were manufactured for sound-absorbing boards in construction. The manufacturing parameters were target density (400, 500, 600, and 700 kg/m³) and rice hull content as percent weight of rice hull/sawdust/phenol resin (10/80/10, 20/70/10, 30/60/10, and 40/50/10). Commercial gypsum board and fiberboard were also used as comparative sound-absorbing materials. The average modulus of rupture (MOR) of the board with a density of 700 kg/m³ and rice hull mixing ratio of 10% was 8. 6 MPa, and that of the board with a 400 kg/m³ board density and a rice hull mixing ratio of 40% was 2. 2 MPa. The MOR increased with increasing board density or decreasing rice hull mixing ratio. The sound absorption coefficients of some boards (400 kg/m³ and 10%, 500 kg/m³ and 30%, and 500 kg/m³ and 40%) were better than those of the commercial 11-mm-thick gypsum board. Thus, it is concluded that rice hull-sawdust composite boards may be implemented as sound-absorbing barriers in construction due to their high sound absorption coefficients.