Technical Note: The Contribution of Perlite to the Sound Transmission Loss of Solid Masonry Walls

Abstract

The sound insulation of solid masonry walls can be improved either by plastering or by changing the constituent materials of the wall blocks. Whilst traditional cement-lime-sand plasters are still in use, plasters containing perlite are preferred, especially in cold climates, due to their high heat insulation characteristics. In this study the contribution of perlite to the sound transmission loss of solid walls is investigated. Two series of measurements were conducted in the laboratory. In the first, perlite was added to the in-laboratory prepared plasters, and in the second perlite was included as an additional constituent to the mixture when casting gypsum blocks. The mean transmission loss of the brick wall was increased by approximately 19 dB when plastered on both sides by plaster containing perlite. When perlite was a constituent of the gypsum wall blocks the average transmission loss was increased by approximately 1 dB.