A new water-retaining paver block for reducing runoff and cooling pavement

In cities, urbanization tends to replace open soils that were naturally used for water storage with impermeable roofs and roads. These impervious surfaces have led to the development of urban heat island effects and to the occurrence of urban flooding during high intensity rainfalls. This phenomenon can be alleviated through the use of water-retaining (WR) pavements to hold rainwater for the subsequent evaporative cooling. These WR pavements are typically constructed as a porous pavement with water-holding media, which occupy the cavity of the matrix and decrease the amount of stored water for evaporation cooling. In this paper, a novel WR paver block is utilized to enhance the water storage capacity of the pavement system by retaining the water in the paver block without the need of water holding layers. The new block retains the water in the block's matrix by sealing the bottom and sides of the block with impervious media. The albedo, temperature, and WR capacities of this new paver block were measured and compared with conventional dense and pervious pavement options. It is found that even though the albedo of a new paver block is 0.10-0.15 lower than a conventional or pervious block, the new block can be 2-10 degrees C cooler. For 6 cm-thick paver blocks, the WR paver block can retain about 9.5 L/m(2) water, which can be removed during a hot sunny day through evaporation. Pavements made of interlocking WR paver blocks can be used as a strategy to mitigate urban heat island and reduce urban runoff simultaneously. (C) 2018 Elsevier Ltd. All rights reserved.X