Sound absorption performance of a triple-hole structure in green ceramsite concrete for high-speed-railway sound barriers: Experiments and neural network modeling

Abstract

Green ceramsite concrete is an environmentally friendly sound-absorbing material for high-speed railway sound barriers. However, given its low sound absorption, this material is not widely used. Therefore, this study proposes a triple-hole structure to improve the sound absorption of green ceramsite concrete. The triple-hole structure comprised micro-sized holes in the ceramsite, medium-sized holes between the ceramsite, and surface macro-sized holes. The surface macro-sized holes were obtained by changing the mold shape, and the other holes were formed by formula control. The influence of the surface macro-sized holes on the acoustic performance of the triple-hole structure was analyzed using an impedance tube test. Results showed that the sound absorption coefficient increased when the hole diameter decreased or the surface porosity increased. The optimal surface macro-sized holes increased the average sound absorption coefficient by 83 %. The surface macro-sized holes improved the acoustic performance by absorbing the reflection of incident sound and not by resonance effect. This effect was attenuated when the relative surface area was increased by more than 100 %. Compared with the ANN method, the finite element simulation method cannot accurately reflect the acoustic effects of the triple hole structure. Back propagation neural network was used to predict the effect and can realize an accuracy of 95.5 %. Thus, this study proposes a reference for the design of sound-absorbing concrete based on frequency.