A review of water transport in dense-graded asphalt mixtures

Water transport in dense-graded asphalt mixtures (DGAMs) is one significant topic for an in-depth study of water damage in asphalt pavements. The X-ray computed tomography (X-ray CT) helps researchers to understand the internal structure of DGAMs and restructure it for numerical simulations of water transport in DGAMs. This review discusses the difference between the internal structure of DGAMs' specimens by laboratory compactions, which include the Superpave gyratory compactor (SGC), the linear kneading compactor (LKC), the Marshall compactor and the vibratory compactor, and field cores and clarifies the purpose of a laboratory compaction. And then the review describes gaseous and liquid water transport in DGAMs, the permeability of three transport media, asphalt mixtures, asphalt mastic and pure asphalt. Numerical simulations of DGAMs are also discussed in the review and confronted problems are set forth that involve the dividing of the gray threshold in X-ray CT images, the restructuring of the 3D model of DGAMs, the permeability of asphalt mastic in this model and the truncation criterion of a water transport process. Future work on water transport in DGAMs is recommended in the end of the review.