Experimental study on the sound absorption performance of surface-perforated mortar

Abstract

This study proposes the surface-perforated mortar (SPM) to mitigate railway noise. As one of the most emerging noise problems, railway noise deteriorates the quality of human lives. This paper investigates the sound absorption performance of SPM and it is compared to that of porous concrete which has been adopted as a potential solution for railway noise. The effects of hole size and depth, and surface porosity on the sound absorption performance of SPM is examined using an in-situ sound absorption test and the results explain the sound absorption mechanism of SPM. Based on these understandings, two methods to improve the sound absorption of SPM without strength degradation are proposed: (i) a combination of different depths of the holes and (ii) an application of sound-absorbing filler into the holes. The improvements show the sound absorption performance of the SPMs more than double that of the porous concrete with 25% design porosity.