Abstract

Urban cities can be several degrees warmer than surrounding regions due to the built environment and concentration of human activities; a phenomenon known as Urban Heat Island. Pavements made of heat absorption materials are one of the major contributors to this effect by altering natural land cover over significant portions of the urban area. This research presents an experimental study aimed at evaluating the effect of water on outdoor pavements as a strategy to mitigate the rise in surface temperatures of pavements. The experiment quantify the thermal performance of three commonly used pavement materials within the study area before and after water was applied with respect to their surface temperature, air temperature and relative humidity above the pavement surface. These variables were observed manually using the Infrared thermometer and the Kestrel weather tracker. The data obtained were analyzed using statistical techniques. Results show that the surface temperature of the three pavements sampled were most elevated during the day, Asphalt was observed to be the hottest material with an average surface temperature of 58.280C, Interlocking concrete tiles was next with 44.140C and clay bricks was the coolest material at 39.870C. The evaporation rate from the wet surface was most rapid during the day; it took 20 min for asphalt, 30 min for interlocking concrete tiles, and 40 min for clay tiles. A significant difference in surface temperature was observed on all samples. However, asphalt was seen to have the best performance after water was applied; with a temperature difference of 120C. Thus this` study concluded that the surface temperature of pavement samples is significantly cooler in presence of water. In other words different pavements have different evaporation rates and classifying outdoor materials in terms of cooling effect is useful and will aid in mitigating heat gains of pavements