Hydro-Mechanical Modeling of Clogging and Seepage Phenomena in Porous Asphalt Pavement

Abstract

The complex hydro-mechanical interactions underlying clogging and seepage phenomena in open-graded friction course (OGFC) pavements remain poorly delineated. A clogging test and numerical modeling were employed to investigate clogging in OGFC-13 pavement by simulating the process and analyzing the effect of air void location on particle distribution. Consequently, the targeted improvement measures of drainage capacity were recommended. The results showed that the calculated permeability coefficients were consistent with the measured value, validating the reliability of the numerical model. The mechanism of layered clogging within the OGFC-13 specimen was characterized by the initial accumulation of larger particles (1.18–4.75 mm) within its surface air voids. The subsequent influx of larger particles led to the formation of a layered structure of smaller particles within the underlying matrix. Meanwhile, a strong correlation exists between the equivalent diameter of the air voids and the size and distribution of the clogging particles. The equivalent diameter of air void of 2.36-4.75 mm in the OGFC mixture was regarded as a key void size in the clogging simulation, and the clogging particles ranging from 1.18 to 2.36 mm were directly implicated in the reduction of the mixture’s air void content. A three-dimensional (3D) model, reconstructed from computer tomography (CT) scans, effectively visualized the microscopic air voids in the OGFC pavement. This analysis revealed a positive correlation between drainage capacity and connected void content, drainage layer thickness, and cross-section slope. Notably, the drainage capacity peaked and then declined as the drainage path length increased. Consequently, pavement drainage in most regions can be improved by increasing the cross-section slope or shortening the drainage path.