Correlating microscopic pore characteristics with permeability coefficient in porous asphalt concrete: an X-ray CT-based approach

The internal void structure of porous asphalt concrete (PAC) is crucial for its drainage performance. This study employs X-ray CT scanning and image processing techniques to analyze key microscopic parameters of PAC, including void porosity, number of voids, equivalent diameter, and fractal dimension. The evolution of these parameters under clogging and cleaning conditions is investigated. A predictive model for the permeability coefficient of PAC is established based on the findings. Results indicate that internal void distribution exhibits similar variations across specimens with different void porosities during clogging and cleaning. Notably, the number of voids increases significantly after clogging, while equivalent diameter decreases and fractal dimension remains stable. All parameters are effectively restored post-cleaning. A strong correlation exists between void porosity, number of voids, equivalent diameter, fractal dimension, and the permeability coefficient, ranked from best to worst as: void porosity, number of voids, equivalent diameter, and fractal dimension, with a correlation coefficient of 0.991 for the predictive model.