Influence of the Thermophysical Properties of Pavement Materials on the Evolution of Temperature Depth Profiles in Different Climatic Regions

The paper summarizes the relative influence of different pavement thermophysical properties on the thermal response of pavement cross sections and how their relative behavior changes in different climatic regions. A simplified one-dimensional (1D) heat-flow modeling tool was developed to achieve this by using a finite difference solution method for studying the dynamic temperature profile within pavement constructions. This approach allows for a wide variety and for daily varying climatic conditions to be applied, where limited or historic thermophysical material properties are available, and permits the thermal behavior of the pavement layers to be accurately modeled and modified. The model was used with available thermal pavement materials properties and with properties determined specifically for the study reported in this paper. The pavement materials included in the study comprised both conventional bituminous and cementicious mixes and unconventional mixtures that allowed a wide range of densities, thermal conductivities, specific heat capacities, and thermal diffusivities to be investigated. Initially, the model was validated against in situ pavement data collected in the United States in five widely differing climatic regions. It was found to give results at least as good as others available from more computationally expensive approaches such as two-dimensional (2D) and three-dimensional (3D) finite-element (FE) commercial packages. The model was then used to compute the response for the same locations where the thermal properties had been changed by using some of the unconventional pavement materials. This revealed that reduction of the temperature range by several degrees was easily possible (with implications for reduction of rutting, fatigue, and the urban heat island effect) and that depth of penetration of peak temperatures was also achievable (with implications for winter freeze and thaw). However, the results showed that there was little opportunity to displace the peak temperatures in time.