Behavior of Asphalt Pavements Subjected to Frost-Thaw Cycles and Traffic

This chapter presents some results of an investigation of the durability of surface layers of asphalt pavements subjected to traffic and frost-thaw cycles using experimental data from large-scale heavy vehicle tests and finite element modeling. The tested pavement is composed of two asphalt layers. The test sequences are carried out under dry and partially saturated conditions for these layers. The focus of this chapter is limited to the analysis of the response of the pavement structure under thermal loading; the response to mechanical loading is not addressed. During the test, high levels of water content in the asphalt materials are reached, and the development of swelling strains in the partially saturated layers, due to phase change of pore water, is clearly evidenced. The swelling strain magnitude in the partially saturated asphalt concrete material is determined through simulation of the test. Moreover, the comparison between the gage measurements obtained under dry and partially saturated conditions shows that a consequence of frost in asphalt concrete is the development of differential horizontal strains between the layers. To reproduce this effect in the simulation, bonding between the asphalt layers must be relaxed reflecting the fact that, in some way, the interface is significantly stressed out what could be detrimental to it.