Evaluation of the aggregate type effect on creep compliance and thermal sensitivity of aged asphalt concrete

Factors such as bitumen volatile materials’ evaporation and oxidation during mixing with stone grains, its transport to the project site and also during pavement servicing will result in bitumen aging and could lead to some failures in asphalt pavements. As a consequence of aging, the bitumen will become brittle and some cracks can be observed on the pavement which lowers the driving quality and increases the repair and maintaining costs. Rutting is also one of failures which will result in decrease of travel safety, and increase of roads’ maintenance costs. Knowing about the characteristics of asphalt composition (bitumen and stone material) could be useful in design of pavements with longer life. Regarding this subject and also this fact that a few studies have addressed the effect of mixture’s physical properties on the resistance parameters of asphalt, in this study, the impact of stone material’s type on creep abilities of aged warm asphalt mixture is investigated. In this context, asphalt samples with two types of limestone and silica stone materials were fabricated and put under aging trend based on standard methods. Then, the samples underwent dynamic creep test in 100 and 300 kPa and temperature of 50 and 60 oC and their stable strains were measured. Finally, the results were analyzed using MATLAB software and an empirical model for creep behavior of aged asphalt concrete with stone material type consideration was presented. The results showed that lime samples, in comparison with silica samples, are more resistant against time-dependent deformation.