Minimum Pavement Temperature Modeling and Mapping for Alaskan Conditions

According to the Superpave design system, the selection of asphalt binder using performance-based binder specifications depends in part on the expected high and low pavement temperatures. For low-temperature cracking considerations, the binder should satisfy minimum pavement temperature requirements selected for design. In this case, knowledge of minimum pavement temperature during the design period is essential for proper binder selection. In this study, field temperature data for a number of sites were collected and analyzed. Correlations between minimum air and pavement temperature were established for different Alaskan climatic zones. Results indicate that the minimum pavement temperature could be lower or higher than minimum air temperature. However, for low temperature ranges the pavement temperature is generally warmer than air temperature by 2 to 7° C, depending on climate zone. Comparisons of minimum pavement temperature for Alaskan conditions with Superpave and the Asphalt Institute criteria for selecting minimum pavement design temperature were made. Results show that the criteria are not appropriate for Alaskan pavements. The Superpave prediction is conservative whereas the Asphalt Institute’s prediction model is unconservative. In addition, contour maps corresponding to 50 percent and 98 percent reliability were developed for minimum air and pavement temperatures. The temperature correlations and contour maps provide a simple tool for design engineers to estimate minimum design pavement temperature for selecting appropriate binder specifications.