Impacts of Lightweight Aggregate Interlayers for Air Convection Embankment on Pavement Thermal Profile and Pavement Performance in Alaskan Permafrost Regions

Crushed-rock air convection embankment (ACE) has been used to mitigate pavement distresses caused by climatic extremes in permafrost regions for more than three decades. This study proposes using lightweight aggregates as cost-effective alternative materials to overcome the shortage of desired crushed rocks needed for ACE in interior Alaska. This paper presents an investigation of the performance of six selected pavement structures: an asphalt pavement typical of the northern region of Alaska and five pavements reinforced with different paving interlayers (i.e., silty sand/gravel, crushed rocks, cellular concrete aggregate, foam glass aggregate, and lightweight expanded clay aggregate). Pavement thermal analyses using Temperature Estimate Model for Pavement Structures (TEMPS) program and ANSYS Fluent software were performed to predict heat transfer patterns and thermal performance for each case. Pavement performance analyses using viscoelastic-based FlexPAVE™ and the elastic-based Alaska Flexible Pavement Design (AKFPD) program were conducted to evaluate the long-term performance and structural stability of subgrade soil with different types of interlayers. The results showed that the lightweight aggregate ACEs improved cooling performance more effectively than the crushed-rock ACE. The lightweight aggregate interlayers could maintain desired thermal insulation in summer and enhance the cooling effect in winter. The modeling results identified the high potential of using lightweight aggregates as alternative ACE materials to improve pavement service life and subgrade stability.