Experimental Investigation of the Hydraulic Performance of a Permeable Block Pavement System Using a Multi-Scale Testing Apparatus

Recent urbanization and climate change have altered the hydrologic characteristics of road surfaces, intensifying urban flooding and associated damage. This study focuses on permeable block pavements, a key LID technology for sustainable urban development, particularly with respect to their application for sidewalks. To quantitatively evaluate the permeability performance of the pavement system and clarify the infiltration mechanisms associated with different combinations of upper and lower aggregates, an integrated permeability testing apparatus was developed. Based on small-scale testing, the coefficient of permeability was quantitatively evaluated according to the gradation characteristics of the base aggregates. The results indicated that as the fine content increased and the coefficient of uniformity (Cu) decreased, the permeability coefficient also decreased. Furthermore, when blocks were added above the base layer, the permeability coefficient showed a decreasing trend, suggesting that even if the upper layers have higher intrinsic permeability, the hydraulic conductivity of the lower layers predominantly governs the overall permeability of the system. Using large-scale rainfall simulation, the permeability was evaluated under a rainfall intensity of 88.2 mm/h. The base-only configuration exhibited the highest storage capacity (approximately 36%), while adding the bedding layer and block pavement reduced the initial outflow time by up to 33 s.