A new sound absorbing lightweight concrete masonry block

Abstract

The purpose of this paper is to present an innovative design approach for a sound absorbing lightweight concrete masonry unit made with expanded clay LECAÒ. This new type of block is presented and acoustically characterized. This block is especially suited for sound control in critical listening or performance spaces as well for noise control in noisy environments like industrial areas, power transformers substations, sound barriers, etc. The block measures 200x200x500 mm3 and weights about 13.8 kg. Its design and weight allows easy placement. Two options were tested: with and without fiberglass inserts (instaled at the block plant) in the unit's Helmholtz resonators chambers. The sound absorption results obtained in the I.D.I.T.'s reverberant chamber using ISO 354 are presented. Sound absorption coefficients (a) above 0.65 for frequency bands between 200 and 400 Hz were found. Noise Reduction Coefficients (NRC) of 0.61 were calculated.