Acoustic properties of concrete panels with crumb rubber as a fine aggregate replacement

This paper presents the acoustic performance of small scale crumb rubber concrete (CRC) panels in terms of the sound absorbance and insulation at low (63, 125, 250 and 500 Hz) and high (1000, 2000, 4000 and 5000 Hz) frequencies. Acoustic tests were conducted with differing levels of fine aggregate replacement with crumb rubber (7.5% and 15%) with four different grades following freezing and heating. Analysis of the workability, compressive strength and density are also presented. The results found that CRC performed well in terms of sound absorbance particularly with higher proportions (15% here) and grades of crumb rubber. As an insulator, the CRC was comparable with plain concrete with only marginal differences observed. Effects of freezing and heating were shown to have no significant influence on the insulation properties. The insulation performance for all concretes was found to improve at high frequencies. The results demonstrate that CRC has potential as an external building cladding to absorb sound around high-rise urban structures but requires full-scale testing on site. This approach offers an environmental friendly solution to the ongoing problem of used tyres.