Impact of different levels of oxidative aging on engineering properties of asphalt mixes at low temperatures

Abstract

Asphalt pavements at cold climates or regions with high-temperature fluctuation are prone to cracking due to the induced thermal stress within the mix. The properties of asphalt mixtures at low temperatures, including stiffness, tensile strength, and fracture energy are of prominent importance in the initiation and propagation of the low temperature or thermal cracks in the pavement. The influence of aging on changing mechanical properties of mixes has been well recognized. This study aimed to gain more insight into how aging affects the low-temperature behavior of asphalt mixtures. Overall, 15 types of asphalt mixes with three binder contents, two aggregate types, and three different binder types (conventional and using two modifiers) were assessed at both short-term and long-term aging conditions using the dynamic modulus test (at −15, 0, and 20 °C), the semi-circular bending test (at −5°C), and the indirect tensile strength test (at −10 °C). In general, aging increased stiffness and reduced relaxation potential of mixes and affected the fracture and strength properties of mixes, adversely. The main finding of this study was that the influence of aging on the thermal cracking critical properties of asphalt mixes was not the same for mixes with different aggregate sources, mixes at different binder content, and mixes with modifiers. Appropriate selection of mix ingredients and volumetric properties were found to be crucial to ensure the resistance of the mix to thermal cracking over the long-term service life of the pavement.