Kopynets I. Increasing the durability of asphalt pavement by reducing the technological aging of bitumen

In the Thesis the relevant scientific and practical issue of increasing the durability of asphalt pavement is solved. Conducted theoretical and experimental studies have established the patterns of changes in the bitumen properties during technological aging, which consist in changing the mass, reducing the penetration at 25 °C, increasing the softening point, brittleness temperature and dynamic viscosity at all temperatures. According to the research results, the method of determining the process temperatures of production and compaction of asphalt mixtures was improved. This method is establishing the mixing temperature of bitumen with aggregate by temperature-viscosity dependence of the source bitumen followed by establishing the compaction temperature of asphalt mixtures by the temperature-viscosity dependence of aged bitumen by RTFOT method at equivalent temperature. It is established that the use of modifying additives based on cationic surfactants and polymers such as SBS leads to increasing the bitumen resistance to technological aging, which is manifested in reducing the change in mass, reducing the softening point, increasing the residual penetration and reducing the aging indexes, and, accordingly, preserving the properties of the asphalt pavement during operation, thereby increasing its durability. Reducing the technological aging of bitumen has a positive impact on the durability of asphalt concrete. At a design temperature of 10 °C, the elasticity modulus of asphalt concrete on the source bitumen is slightly higher than the elasticity modulus of asphalt concrete on modified bitumen. At low operation temperatures, modified asphalt concretes are less rigid, and at high operation temperatures in the case of surfactants using – are identical to asphalt concrete on the source bitumen; in the case of polymer using they are more rigid, which allows predicting higher durability of asphalt pavement at increasing the bitumen resistance to aging. The fatigue life of asphalt concrete grows with increasing resistance of bitumen to technological aging. At the same time, asphalt concrete on the polymer modified bitumen is more durable. The increased fatigue life of the modified asphalt concrete is preserved during operational aging, which indicates an increase in the durability of the asphalt pavement as a whole. Measures to increase the durability of asphalt pavement, including the choice of bitumen for the production of asphalt mixtures taking into account its technological aging, increasing the bitumen resistance to technological aging, including the use of modifying additives, as well as organizational measures to prevent bitumen aging under temperature were developed.