Modeling and Optimization of Acoustic Absorption for Porous Asphalt Concrete

Abstract

The aim of the study is to investigate the influence of pore structure on acoustic absorption of porous asphalt concrete (PAC) and to obtain the optimum pore structure for achieving the maximum acoustic absorption capacity. The Zwikker and Kosten model for rigid-framed porous materials was implemented with transfer-matrix method to predict the acoustic absorption coefficient of PAC considering the idealized pore structure parameters (pore radius, pore length, and porosity). The predicted results were compared with experimental measurements reported in the literature, and the model was validated. Sensitivity analysis was conducted to evaluate the influences of pore structure parameters on acoustic absorption spectra of PAC. The results show that an increase in pore radius can reduce acoustic absorption. Increasing porosity results in a reduction of acoustic absorption but an increase in the frequency range where the maximum acoustic absorption occurs. Conversely, increasing pore length (as an indication of PAC layer thickness) causes the maximum absorption occurring in the lower frequencies. Simulated annealing (SA) algorithm was developed to determine the optimum pore structure for improving sound absorption performance of PAC considering different tire-pavement noise generation mechanisms. The application of acoustic absorption model along with the optimization algorithm provides a useful tool for guiding mix design of PAC in terms of acoustic performance.