Characterization of Three-Dimensional Internal Structure Evolution in Asphalt Mixtures during Freeze–Thaw Cycles

This paper aims to characterize the three-dimensional (3D) internal structure evolution of asphalt mixtures under freeze–thaw cycles. Asphalt with three levels design void content (3%, 5%, and 7%) were prepared in laboratory. Subsequently, X-ray computed tomography (CT) tests conducted capture two-dimensional (2D) images samples before after testing. A set image processing techniques for reconstructing 3D utilized extract properties, which then used analyze changes air distributions evaluate reconstructed from CT illustrated a dramatic degradation cyclic exposure. The change occurs mainly ways: (1) expansion existing individual voids, (2) combination two separated (3) generation new voids. In addition, parametric analysis voids revealed that mixture ratio increased number cycles, while larger initial content, more pronounced increase specimens. Therefore, resistance should be optimized relation content.