Influence of Sustainable Technologies on In-Place Thermal Properties of Asphalt Pavements

A study of the in-place thermal cycling of asphalt pavements containing select sustainable technologies, such as reclaimed asphalt pavements (RAP), recycled asphalt shingles (RAS), and ground tire rubber (GTR) was performed using multiple test sections built at the National Center for Asphalt Technology (NCAT) Test Track. For a period of six months, hourly measurements of the pavement temperature were taken at different depths within the asphalt layers. Simultaneous hourly measurements of the ambient air temperature, wind velocity and solar radiation were also obtained. The results were used to estimate the energy absorbed by the pavements and the heat conducted through the asphalt layers. An unconventional parameter, based on heat transfer theory (termed “field thermal conductivity” for the purpose of this study) was proposed to compare the heat conduction characteristics of the three sustainable pavement systems included in the study. A statistical analysis of the results revealed that the use of RAP, RAS, and GTR-modified binders affected the in-situ thermal properties, warranting further investigation.