A new structure of permeable pavement formitigating urban heat island

The urban heat island (UHI) effect has been a great threat to human habitation, and how to mitigate this problem has been a global concern over decades. This paper addresses the cooling effect of a novel permeable pavement called evaporation-enhancing permeable pavement, which has capillary columns in aggregate and a liner at the bottom. To explore the efficiency of mitigating theUHI, bench-scale permeable pavement unitswith capillary columns were developed and compared with conventional permeable pavement. Criteria of capillary capacities of the column, evaporation rates, and surface temperature of the pavements were monitored under simulated rainfall and Shanghai localweather conditions. Results showthe capillary columnwas important in increasing evaporation by liftingwater fromthe bottomto the surface, and the evaporation-enhancing permeable pavementwas cooler than a conventional permeable pavement by as much as 9.4 degrees C during the experimental period. Moreover, the cooling effect of the former pavement could persist more than seven days under the condition of no further rainfall. Statistical analysis result reveals that evaporation-enhancing permeable pavement can mitigate the UHI effect significantly more than a conventional permeable pavement. (C) 2018 Elsevier B.V. All rights reserved.