Research on Heterogeneity Regulation of Composition Structure for Dense-graded Asphalt Mixture

The composition of asphalt mixtures exhibits notable heterogeneity because of the cross-scale transmission of the heterogeneous characteristics of raw materials, which limits the effectiveness of performance-oriented mixture designs and significantly influences the performance and service life of asphalt pavements. Therefore, this study aimed to quantify the heterogeneity of the asphalt mixture composition structure. To elucidate the impact of coarse aggregate characteristics on the heterogeneity of the composition structure, a method was proposed to regulate the heterogeneity of the asphalt mixture composition structure. The goal was to reduce performance variability and enhance pavement reliability. To this end, a random experimental database containing 100 digitized asphalt mixtures was established. Based on correlation and significance analyses, the parameter system for the asphalt mixture composition structure was optimized. Analysis models based on interaction effect analysis and undersampling data balancing methods were developed for the heterogeneity of asphalt mixture composition structures. Marginal effect analysis was employed to develop control standards for the coarse aggregate parameters to regulate the heterogeneity of the asphalt mixture composition structure. The accuracy and applicability of the regulation method were validated using data points from a random experimental database not used in the model construction. This study shows that optimizing the particle size distribution and morphological characteristics of coarse aggregates can effectively regulate the heterogeneity of the asphalt mixture composition structure. The interaction effects of the coarse aggregate parameters on the composition structure regulation were stronger than the main effects. Among them, the interaction effect between the particle size distribution of the main skeleton aggregates (4. 75–9. 5 mm) and average angularity of the skeleton aggregates (4. 75–19 mm) reduced the heterogeneity of the composition structure parameters by more than 80. 5%. Regulating the multifractal spectrum difference of the void structure led to a nearly 50% reduction in the overall heterogeneity of the asphalt mixture composition structure, proving the effectiveness of single-parameter regulation in enhancing the overall stability of the composition structure. This study proposes a method for controlling the heterogeneity of asphalt mixture composition structure, providing new insights for optimizing the performance of asphalt mixtures. It holds significant practical value in improving pavement reliability and extending service life.