Effect of air void topology on the hydraulic conductivity and clogging properties of pervious asphalt roads

Abstract

This paper explains the effect of air void topology on the hydraulic conductivity and clogging properties of pervious asphalt. Cylinders of asphalt mixtures with a single type of aggregates and five gradations have been manufactured, Computed Tomography (CT) scanned and, transparent resin blocks with equivalent pore structure have been 3D printed to allow the visual inspection and quantification of the clogs. Geometrical properties, such as the macroporosity, air void diameter, Euler number and tortuosity, have been recorded from the CT scans. Furthermore, the hydraulic conductivity and clogging susceptibility of the asphalt cylinders and 3D-printed resin blocks have been measured. It has been found that the air void diameter and porosity are the parameters that most affect the movement of water and solids through the porous asphalt. In the mixtures studied in this paper, these two parameters can be directly correlated to the tortuosity and Euler number of the asphalt mixtures. Higher macroporosity implies higher hydraulic conductivity so as lower clogging susceptibility. In order to use the results of this paper to design new pervious pavements, further research is required where the clogging properties of mixtures with a wider range of aggregate gradations, maximum sizes and geometries is studied.