Concrete panels and the sound of music

THE excellent sound insulation qualities of the prestressed hollow-core concrete floor slab system – added to the bonus of speed of construction, quality finishes and economy – were high-priority reasons for the selection of Echo Prestress flooring panels in the construction of Durban’s elegant new KZN Music House.

The recording studio is essentially a simple brick-built cell supporting a roof of 150mm- and 250mm-depth concrete panels which create the necessary “dead” sound, while a “floating” fibreglass-filled sandwich of ceiling and interior walls provide additional sound insulation.

Using the hollow-core panels for the studio areas avoided propping and shuttering of wet concrete, once again highlighting the economy and labour-saving features of the system. Convincing evidence of this was the fact that the project was completed six weeks ahead of programme.

Eric Quevauvilliers of the main contractor, Pratique, says hollow-core floor concrete slabs are known to provide a high level of acoustical insulation to airborne sound transmission. “In this way they are similar to solid concrete slabs in the transmission of impact noise and airborne sound which, when it reaches the floor, vibrates it, and is then radiated through the floor material.”

Airborne sound transmission loss is most greatly affected by the weight of the material. For this reason, a hollow-core, precast concrete floor system did not require any additional treatment to achieve good sound insulation.

Acoustics engineer Steve Moss reported that overall performance of the studio was 15% better than specified.