A Three-Dimensional Optimization Framework for Asphalt Mixture Design: Balancing Skeleton Stability, Segregation Control, and Mechanical Strength

The composition design of asphalt mixtures plays a pivotal role in determining pavement performance and durability. To improve skeleton stability, paving uniformity, and mechanical strength, this research proposes a three-dimensional optimization framework for asphalt mixture design, focusing on aggregate gradation and optimum asphalt content. A skeleton-dense and anti-segregation gradation optimization method was developed by integrating a previously established skeleton-dense model with a segregation tendency prediction approach. In parallel, a mechanically driven method for determining optimum asphalt content was proposed by introducing the maximum migration shear stress as a performance-based alternative to the conventional Marshall stability parameter. Research results show that asphalt mixtures designed and compacted with the optimized gradation exhibit significantly enhanced high-temperature stability, while maintaining satisfactory low-temperature cracking resistance and moisture susceptibility. Field validation was conducted through the construction of a trial pavement section using the optimized gradation under recommended mixing and compaction temperatures. The resulting pavement demonstrated excellent compaction, strong resistance to segregation, and a highly stable spatial structure. These findings confirm the effectiveness of the proposed methodology in enhancing the high-temperature deformation resistance and overall structural integrity of asphalt mixtures.