Low-carbon straw-reinforced asphalt mixtures: Influencing factors, impact mechanisms, and mesoscopic characteristics of pavement performance

This study investigates the incorporation of wheat straw flake (WSF) into asphalt mixtures to facilitate the resource utilization of agricultural waste and to systematically evaluate the enhancement of pavement performance. Through a combined methodology of rutting tests, bending beam tests, split tensile tests, computed tomography (CT) meso-structural scanning, and theoretical analysis, the macroscopic performance and meso-structural characteristics of WSF reinforced asphalt mixtures were examined. The primary and secondary influence of key straw fiber parameters (namely content, length, and moisture content) on the mixture’s performance was elucidated. Results demonstrate that WSF possesses suitable thermal resistance for asphalt construction, with an effective operational temperature range of 130–160 °C. The formation of a three-dimensional network structure by WSF within the mixture contributes to significant improvements in both high- and low-temperature performance; however, its inherent hydrophilicity constrains the enhancement of moisture stability. Meso-structural analysis indicates that an optimal WSF content refines the mixture’s pore structure by reducing the proportion of small-diameter and isolated pores while increasing the pore coordination number, thereby improving compactness and structural stability. The relative significance of the factors on performance is ranked as follows: WSF content > moisture content > length. This study provides a valuable reference for the engineering application and mix design of analogous fiber-reinforced asphalt materials.