Large-scale clogging experiments assessing the hydraulic performance of porous asphalt during their service life

This study investigates the long-term behaviour of a porous asphalt that retrofitted a 36 m² laboratory full-scale street section, in terms of filtration and clogging processes. Throughout 11 experiments with increasing accumulative sediment loads up to 5.5 kg/m², the evolution of surface permeability, water levels inside the asphalt, water flows, turbidity, and TSS concentrations were analyzed. Sediment loads, representing dry-weather buildup, were applied to the asphalt surface followed by simulated 30-minute 80 mm/h rain events. Findings revealed an average permeability reduction rate of 4717 mm/h per kg/m². Surface clogging appeared from a cumulative load of 4.0 kg/m², but the asphalt effectively managed rainfall with only marginal variations in flows and water levels, except for the vicinities of gully pots. The porous asphalt demonstrated a sediment retention efficiency of 93%, with a significant decrease in turbidity and increasing TSS concentrations once the asphalt clogged. Comparison with previous work emphasized the scalability and reliability of small-scale test results for analyzing permeability evolution and retention efficiency, but such tests overlook real-world heterogeneities compromising the representativeness of water and sediment fluxes. The experimental dataset provides novel and valuable data for developing models to accurately simulate permeable pavements towards better urban planning, design, and maintenance.