Penetration mechanism of the emulsion-based rejuvenator in damaged porous asphalt mixture: Microstructure characterization and 3D reconstruction

Porous asphalt (PA) pavement suffers from the early-stage raveling problem, which hinders the wide application of this sustainable technology. Several promising attempts have been made to restore the durability of PA wearing courses by using surface treatment (ST) emulsions. However, the working mechanism of the ST emulsion is still unclear. Therefore, this study aims to investigate the penetration behavior of the ST emulsion in damaged PA. X-ray CT scanning was performed to monitor the changes in the pore microstructure of PA specimens under three selected ST conditions. The spatial distribution of ST emulsion residue was back-calculated and 3D visualized through image analysis. The coating efficiencies and thickness distributions of ST emulsions were quantitatively estimated to characterize their penetration status. The analysis results showed that the distribution of ST emulsions in damaged PA presents gradient characteristics with a deepest penetration depth of around 20 mm. The ST application reshaped the interconnected-pore microstructure. The PA specimen treated by ST emulsion with best coating efficiency and thickest coating film showed the best performance recovery among the three ST conditions. The outcomes of this study are expected to help optimize the performance of the ST technology for PA, thus contributing to more durable PA pavements.