Compressive Properties and Failure Behavior of Aggregate-Segregated Asphalt Mixtures: Laboratory Testing and Digital Image Correlation Approach

To investigate the compressive properties and failure behavior of aggregate-segregated asphalt mixtures from an integrated macro-meso perspective, AC-13 and OGFC-16 asphalt mixtures with varying degrees of segregation were designed and prepared for uniaxial compression tests. Using digital image correlation (DIC) technology, the first derivative of the load-time curve of segregated asphalt mixtures and the horizontal displacement rate on both sides of the primary crack were studied. Additionally, the failure process of segregated asphalt mixtures was explored, and a parameter was proposed to evaluate the failure width of the primary crack. The results show that both compressive strength and failure displacement of AC-13 segregated asphalt mixtures initially increase and then decrease as the degree of aggregate segregation rises. For OGFC-16 segregated asphalt mixtures, the peak load continues to rise with the increasing degree of aggregate segregation, resulting in greater compressive strength and failure displacement. Following aggregate segregation, the trends in the variation of elastic energy and dissipated energy for both AC-13 and OGFC-16 asphalt mixtures are consistent with compressive strength and failure displacement. The load-time curves can be segmented into four distinct stages such as the slow growth period, growth period, attenuation period, and period corresponding to negative values, based on the first-order derivative. Coarse-aggregate segregation results in the premature formation of initial cracks, subsequent crack propagation, and eventual failure of the AC-13 mixture, making the AC-13 segregated asphalt mixture more susceptible to adhesive failure, characterized by a significant difference in horizontal displacement rates on either side of the primary crack. Conversely, fine-aggregate segregation delays the onset and development of cracks, so the OGFC-16 mixture mainly manifests as cohesive failure, evidenced by smaller differences in horizontal displacement rates on either side of the primary crack. The proposed parameter, Wv, provides an effective means to assess the deformation capacity of asphalt mixtures after initial cracks appear but before the onset of macroscopic failure.