Investigation of the Use of Lightweight Aggregate Hot-Mixed Asphalt in Flexible Pavements in Frost Susceptible Areas

Frost related damage in pavements is a major concern for highway engineers in cold regions. The existing methods for mitigating frost damage in flexible pavements are expensive; they require greater construction control and are not fully effective. This paper investigates an alternative approach for reducing frost penetration into the pavement layers by engineering a less conductive asphalt surface layer. It proposes a less conductive pavement by replacing conventional aggregate in the asphalt mix with lightweight aggregate (LWA). The paper discusses, in the context of the larger research program, the development of an optimized design of LWA-asphalt mix. It is has been demonstrated in work published elsewhere that because of its superior insulating behavior, LWA-asphalt mix can reduce frost penetration into the underlying pavement layers. Thus maintenance cost associated with frost damage can be reduced. This paper presents the physical properties of LWA, the lessons learned from the mix design process, as well as the preliminary thermal and mechanical properties of the optimized LWA-asphalt mix.