Impact sound transmission provided by concrete layers incorporating cork granules

We report on the development of lightweight cement-based screeds containing cork granule waste. The reduction of transmitted impact noise provided by these screeds has been assessed by means of laboratory measurements in acoustic chambers at ITeCons (Instituto de Investigação e Desenvolvimento Tecnológico em Ciências da Construção). The screed has been tested in two situations: over a heavyweight standard floor (reference laboratory floor) and as a resilient layer between the heavyweight standard floor and a floating concrete layer. Three different screeds were designed, with varying cement dosages. Thicknesses of 1.5, 3 and 4.5 cm were tested for each screed mixture. As the impact sound reduction of resilient materials is related to their dynamic stiffness, this was also measured in laboratory conditions. The results of dynamic stiffness were generally found to be related to the values of impact sound reduction when the cement/cork screed is used as floor covering. The results obtained show the potential of these composites in applications for reducing impact noise.