Sound-absorption simulation and analysis of double-layer porous asphalt based on mesoscopic pore structure

While most studies evaluate sound-absorption performance of double-layer porous asphalt (DLPA) pavement using macroscopic approaches, this research conducts mesoscopic analysis through acoustic simulations. DLPA's acoustic behavior was examined by reconstructing its three-dimensional (3D) mesoscopic pore structure using an integrated approach. This approach combined X-ray CT scanning, discrete element method (DEM), and digital image processing. Three macroscopic parameters and three mesoscopic parameters were employed to characterize the DLPA's properties. Laboratory-validated finite element method (FEM) simulations assessed how these parameters individually and jointly affected sound-absorption performance of DLPA. The results revealed that lower-layer parameters exerted approximately twice the influence on sound absorption compared to upper-layer characteristics. Maximum noise attenuation of 27% was attained by elevating mesoscopic and macroscopic characteristics in the lower layer (except thickness) while reducing equivalent upper-layer parameters. Notably, owing to Helmholtz resonance effects, DLPA with "two-sieve-gap" configurations (e.g., PA-10+PA-20) demonstrated superior sound absorption performance compared to conventional "one-sieve-gap" designs (e.g., PA-13+PA-20). Targeted optimization of all three mesoscopic parameters could achieve noise-reduction coefficients of 0.4, providing a scientific basis for designing high-performance DLPA pavements with exceptional acoustic properties. • Mesoscopic pore structure of DLPA is reconstructed through an integrated approach. • Sound-absorption performance of DLPA sample is simulated and analyzed. • Decisive roles of macroscopic or mesoscopic parameters in lower layer are emphasized. • DLPA with "two-sieve-gap" configuration is recommended for its acoustic properties.