Evolution of clogging of porous asphalt concrete in the seepage process through integration of computer tomography, computational fluid dynamics, and discrete element method

The longevity of porous asphalt pavement is inevitably compromised by the clogging of voids by various particles, leading to a degradation in its drainage function. Numerical simulations with real pore structures were used to investigate the clogging behavior of porous asphalt concrete (PAC) to clearly and intuitively understand its void clogging process. In this study, a three-dimensional model of the real void was created by computed tomography scanning. The change before and after void clogging of PAC was characterized by seepage pressure and seepage velocity in the seepage field. The computational fluid dynamics-discrete element method coupling method was used to visually describe the dynamic evolution of clogging particles in porous asphalt voids. Findings reveal that the most influential particle size for clogging in PAC-13 with 18% and 20% porosity ranged between 0.15 and 0.6 mm. In contrast, for PAC-13 with 25% porosity, the sensitive size was 0.3–1.18 mm. When clogging occurred, large particles predominantly obstructed the void inlets, prompting a refinement in the void structure. Subsequent particles either traversed the void, accumulating at the entrances of finer voids, or filled up progressively, leading to eventual clogging. Small particles either exited directly through the voids or accumulated in the bends of the voids, making the voids clogged directly. Consequently, the clogging behavior of porous asphalt was classified into three types: surface-filling clogging, void refining filter clogging, and void bending or semi-connecting clogging. These findings provide a scientific basis for optimizing PAC design and developing conservation strategies.