Comparison of Permeability and Clogging Characteristics of Porous Asphalt and Pervious Concrete Pavement Materials

Porous pavements have been used for many years worldwide because of their unique functional benefits, including improved wet-weather driving safety, reduced tire–pavement noise, lower peak flow load of road drainage systems, and replenishment of groundwater supplies. These benefits are derived from the relatively high porosity and permeability of the porous pavement layers. In the design of a porous pavement, two key considerations are its drainage capacity and its ability to retain the drainage capacity during its service life. In this research, which used a permeability coefficient as the drainage capacity parameter, a laboratory study was performed to examine the drainage and clogging characteristics of two common forms of porous materials used in porous pavement construction, namely porous asphalt and pervious concrete. The experimental program considered four target porosity levels for each of the two pavement materials: 10%, 15%, 20%, and 25%. Clogging was created by introducing clogging materials progressively into the porous materials tested. A constant-head test was employed to determine the permeability coefficients of the porous materials at stages of the clogging test, and the clogging performance was determined by monitoring the reductions in the permeability coefficient as clogging developed. Both porous asphalt and pervious concrete showed significant gains in permeability and clogging resistance when the porosity was raised beyond 20%. The test results also showed that, at any given level of porosity within the range of porosity levels studied, pervious concrete produced higher permeability and better clogging resistance than porous asphalt.