Mechanistic insights into long-term clogging of pervious concrete containing untreated and modified recycled aggregates: CT-based pore evolution and particle capture modeling

This study investigates the long-term sediment-induced clogging and permeability degradation of recycled aggregate pervious concrete (RAPC) under controlled hydraulic conditions. Recycled aggregate (RA) derived from mixed brick–concrete demolition waste was treated using sodium silicate–silane (SS), pozzolanic slurry (PS), and their combination (PS–SS). Repeated clogging tests were conducted using representative road-deposited sediments, while computed tomography and Avizo-based pore-network analysis were employed to characterize changes in porosity, pore volume, throat geometry, and tortuosity. Increasing the untreated RA replacement level from 40% to 60% reduced the initial permeability coefficient by 20.71–31.06% relative to natural aggregate concrete (NAC). NAC reached the predefined clogging endpoint after eight cycles, whereas untreated RAPC reached it after five to six cycles. At the 50% RA replacement level, SSRAC reached the endpoint after four cycles, while PSRAC and PS-SSRAC remained permeable for six and seven cycles, respectively. Clogging primarily reduced connected porosity, divided large connected pores into smaller sub-pores, and narrowed pore throats. A particle-capture-based model was developed to describe the attenuation of the average equivalent pore diameter. The calculated values differed from the corresponding post-clogging CT measurements by less than 5%, supporting the internal consistency of the model under the tested conditions. Finally, three recurring pore-structure patterns were descriptively identified, and corresponding pore-structure-informed maintenance hypotheses were discussed. The integrated experimental, imaging, and modeling framework provides mechanistic insight into the long-term hydraulic degradation of RAPC.