Clogging characteristics and recovery effects of porous asphalt concrete with different gradations

Permeable pavement is easy to be blocked, which significantly affects the functions of drainage and skid resistance. Relevant researches lack void clogging and cleaning for PAC with different air voids and nominal maximum particle sizes. This paper designed seven kinds of PAC specimens to study PAC's clogging characteristics and cleaning methods. Specifically, the permeability coefficient decay of PAC caused by clogging was tested. Then, a novel test called fluorescence tracing method was proposed to evaluate the clogging depth and area. Afterward, high-pressure washing, vacuum cleaning, and the combination of high-pressure washing and vacuum cleaning (H&V) were used to study void recovery characteristics. Results showed that the critical clogging particle size of PAC-13 with 16% air voids and PAC-10 with 20% air voids were 0.15-0.3 mm; the critical clogging particle size of PAC-13 with 18% air voids was 0.3-0.6 mm; the critical clogging particle size of PAC-13 and PAC-16 with air voids of 20%, 22%, 24% were 0.6-1.18 mm. Furthermore, the clogging depths of PAC-13 didn't exceed 28 mm, and the proportions of the clogging area didn't exceed 37%. The average recovery rates of vacuum cleaning and H&V were more than 70%, obviously better than that of high-pressure washing.