Improving the Thermal Properties of Asphalt Concrete to Reduce Urban Heat Island Effects
This study emphasizes on the identification of the asphalt concrete pavement materials that affect the surface temperatures and hence influence their contribution to the urban heat island (UHI) effects. The dark colored asphalt pavement contributes to the increase in the ambient temperatures in the urban areas. Hence, UHI is closely associated with the thermal properties of the pavement materials such as albedo, coefficient of thermal conductivity and the specific heat capacity. The goal of this study is to analyze the effect of alternative aggregate materials, such as limestone, silica, polymer, glass and graphite, have on the asphalt concrete surface temperatures under various environmental conditions. The thermal properties of the asphalt concrete change based on the type of the innovative materials used which ultimately alters the pavement temperatures. To estimate the thermal property change, the asphalt concrete is modeled using a finite element modeling approach for the various modes of heat transfer with respect to the arrangements of the pavement materials. Pavement surface temperatures are analyzed for two extreme weather conditions in USA, namely South Texas and Northern Minnesota. LTTP weather data over a year long period, were analyzed for each location using the computer temperature simulation model, TEMPS. The sensitivity analysis is performed to determine the trend of the increasing and decreasing magnitude of the coefficient of thermal conductivity, heat capacity and albedo of the asphalt concrete layer. Minimum and maximum pavement temperatures at a depth of 0.01 m are compared for both the modified and unmodified asphalt concretes. The mechanical performance of the thermally modified asphalt concrete is then compared to the conventional asphalt concrete to evaluate the improvements in the modified asphalt pavement.