Improvement of acoustic model and structural optimization design of porous asphalt concrete based on meso-structure research.

• Square region segmentation algorithm was proposed for CT image segmentation. • Zwikiker-Kosten model of rigid skeleton porous material was improved. • Parameters for road design dominated by small vehicles were recommended. In order to further reveal the influence of voids on sound absorption performance of porous asphalt pavement, more factors were considered to improve an acoustic model (Zwikiker-Kosten) and structural optimization design of porous asphalt concrete (PAC) based on meso-structure was conducted in this paper. Based on the Otsu algorithm, a square image segmentation algorithm was proposed through comparative analysis to obtain the meso-structure characteristic parameters of voids in porous asphalt concrete. Combined with the effect of airflow velocity on the flow resistance and the measured sound absorption spectrum, the relationship between void length and pavement thickness was quantified, and the Zwikiker-Kosten model of rigid skeleton porous material was improved and verified for the prediction of sound absorption performance of PAC. Besides, the influence of void parameters on the sound absorption performance of PAC was analyzed, the structural optimization design was carried out for the road dominated by small vehicles, and proposing pavement design parameters at last. The results show that the two-dimensional air voids obtained by square region segmentation algorithm have high accuracy, which can be used for the recognition and segmentation of voids in CT images; According to the comparative and correlation analysis, the improved Zwikiker-Kosten model can accurately predict the sound absorption performance of PAC; The peak sound absorption coefficient (SAC) of PAC is mainly affected by air voids, while its corresponding frequency is mainly affected by the length of voids. Moreover, the road dominated by small vehicles was recommended to adopt the following design parameters: void equivalent diameter, air void and pavement thickness should be limited to about 3 mm, 18% and 30 mm, respectively. [ABSTRACT FROM AUTHOR]