INVESTIGATION OF THE AGING PROCESS OF TAR AND DEEPLY OXIDIZED BITUMEN

Abstract

This study investigates the patterns of thermo-oxidative aging of tar and deeply oxidized bituminous binders with different degrees of oxidation. The processes of technological and chemical aging occurring under the influence of high temperatures and atmospheric oxygen during the production, transportation, and operation of asphalt concrete pavements were considered. Tar IV and deeply oxidized bitumen samples with different softening temperatures were used as research objects. The aging kinetics were evaluated by changes in the softening point after aging according to GOST 33140-2014, as well as under technological aging conditions at 163 °C for 5 hours with continuous stirring. Based on the obtained experimental data, the rates of chemical and technological aging of the binders were calculated. It was established that the maximum rate of property changes is observed during the first hours of aging. The results showed that tar undergoes the most intensive property changes during technological aging, whereas deeply oxidized bitumen is more susceptible to chemical (thermo-oxidative) aging. It was revealed that an increase in the degree of bitumen oxidation leads to higher rigidity, viscosity, and aging susceptibility due to the increased content of resin-asphaltene structures. The obtained results make it possible to evaluate the influence of aging processes on the properties of bituminous binders and can be used in the development of compounding technologies and improvement of the durability of road bitumen.