Recycling of agricultural waste: Characteristics and distribution of meso-voids in straw flake asphalt mixtures and their correlation with pavement performance

This study aims to elucidate the mesoscopic void characteristics of straw flake-reinforced asphalt mixtures and their correlation with pavement performance by systematically analyzing the mesostructure using industrial computed tomography (CT) scanning coupled with three-dimensional (3D) reconstruction techniques. The results indicate that increased straw content and reduced flake length both contribute to a notable increase in the population of small-sized voids with equivalent diameters in the range of 0∼1 mm within the mixture. Notably, at a straw content of 0.2% and a flake length of 15 mm, the asphalt mixture exhibited a pronounced tendency to develop a uniformly distributed and well-interconnected void network, thereby enhancing the internal homogeneity and water transport capacity of the composite. Statistical analysis of the mesoscopic parameters reveals that void volume, sphericity, and equivalent radius follow a Weibull distribution, whereas equivalent diameter, coordination number, and throat length conform more closely to a Gamma distribution. Correlation analysis between the mesoscopic void characteristic parameters and pavement performance indicators reveals signification positive correlations: coordination number correlates positively with high-temperature stability, equivalent diameter with low-temperature crack resistance, and sphericity with water stability. These findings provide a robust scientific basis for the rational valorization of straw resources and the targeted regulation of asphalt mixture performance.