Use of lightweight aggregate to mitigate frost damage in flexible pavements

Abstract

This paper investigates the use of lightweight aggregate (LWA) in hot mix asphalt and aggregate base and subbase layers as a strategy of reducing frost damage in pavements. The paper compares thermal conductivity, thermal diffusivity and specific heat capacity of LWA–asphalt mix with those of a conventional asphalt mix. Thermal properties were determined using the k-Alpha Tester developed at the University of New Brunswick. Test results showed that the LWA–asphalt mix has lower thermal conductivity and thermal diffusivity. The LWA–asphalt mix also showed higher specific heat capacity compared to a conventional mix. A finite element thermal response model was analysed to verify if the LWA–asphalt mix would in fact control frost penetration compared to a conventional asphalt mix. The findings showed that the use of LWA–asphalt surface course and a LWA base or subbase course in a pavement will completely eliminate frost penetration into the subgrade.