Study on the influence of void evolution of porous asphalt concrete on acoustic absorption performance under high-temperature loading

Abstract

This paper investigated the void evolution in porous asphalt concrete (PAC) under high-temperature loading and the resulting decay in acoustic absorption performance. The specimen of PAC-13 with a void content of 20.2 % was designed and loaded with MMLS3 for 0–100,000 cycles at 60℃. Computed tomography techniques were employed to extract the distribution characteristics and structural parameters of voids. Subsequently, the acoustic absorption coefficients were measured at different loading stages. The results indicate that PAC experienced both rapid and gradual reduction phases in air void content under high-temperature loading. After 100,000 cycles of loading, the air void content decreased by 5.44 %, void connectivity decreased by 4.32 %, and the average number of voids in section reduced by 8.30 %. The distribution range of nearly 90 % of void sizes shifted from below 7 mm to below 6 mm after 100,000 cycles. At different loading stages, the void content, average number and average equivalent diameter of connected voids exhibited a positive correlation and similar trends with the absorption capacity of PAC for small vehicle noise. This study provides novel insights and perspectives into the acoustic performance degradation of PAC due to void evolution under high-temperature loading.