Acoustically efficient concrete: acoustic absorption coefficient of porous concrete with different aggregate size

Porous absorbers are the most widely used type of acoustically absorptive materials. The interest on their outdoor applications has put further attention on the use of porous concrete in the building industry. This work investigates the acoustic properties of porous concrete. The assessment of the sound absorbing performances has been conducted in the small-scale reverberation room of Politecnico di Torino (Italy), in agreement with the indication in the ISO 354:2003 Standard. For each concrete type, three panel thicknesses, i.e. 20 mm, 40 mm, 60 mm were tested. Moreover, different mounting methods were tested, considering the presence of an airgap between the panel and the backing, and considering the introduction of rockwool in the airgap itself. The result show weighted absorption coefficients (aw) in the range 0.30-0.75 depending on the thickness and mounting conditions. These encouraging values make these materials useful for practical applications in architecture and civil engineering.