EFFECTS OF SALT FREEZE DAMAGE ON THE VISCOELASTIC PERFORMANCE OF ASPHALT MORTAR

In cold regions, road pavements are frequently covered by ice and snow because of low temperatures and extreme weather conditions during winter. Deicing salt is commonly used to reduce icing coverage and clean pavements. However, the repetitive use of deicing salt may have a negative impact on the pavements that are made from a mixture of asphalt mortar and coarse aggregate. This paper discusses the viscoelastic behavior of asphalt mortar in salt freezing environments. The study consists of three steps. First, uniaxial creep tests are conducted on asphalt mortar specimens under different freezethaw cycles. Then, a Burgers model with a damage factor is proposed in order to obtain the viscoelastic parameters. Finally, scanning electron microscopy (SEM) is used to study the microstructure of asphalt mortar and to investigate the structural changes that take place during freeze-thaw cycles. The results of the study indicated that freeze-thaw cycles with different salt concentrations can damage asphalt mortar and change its viscoelastic properties. The Burgers damage model is shown to reflect the creep of asphalt mortar more accurately than the Burgers model. From the results, it can be concluded that it is necessary for cold regions to control vehicle overloading and limit the amount of deicing salt to be used on pavement.