Aging of Sandy Asphalt Mixes with Anti-aging Additives
The object of research is sandy asphalt concrete mixtures. Asphalt concrete in the process of preparation and operation irrevocably reduces its mechanical properties, which is called aging. This process depends on the composition, structure, and size of mineral materials, the physical and mechanical properties of the bitumen used, temperature, and other factors. To reduce the intensity of aging of asphalt concrete, a method has been proposed to improve its properties by introducing additives of anti-aging agents. Method. When preparing sandy asphalt concrete mixtures, various additives are introduced into their composition. Subsequently, samples are formed, and a comparative assessment of various physical and mechanical properties is carried out. Carbon black, sulfur, and the stabilizing additive Viatop-66 were used as additives. The estimation of the rate and intensity of aging was established according to the method provided for by the patent of the Russian Federation No. 2654954 (Volga State Technological University, Department of Building Technologies and Highways). Aging was carried out by preliminary keeping the prepared mixtures in an oven at a temperature of 150 °C for 1, 3, 5, and 7 hours. The static modulus of elasticity was estimated by stepwise loading of asphalt concrete samples by fixing the values of total and residual deformations. Results. It was found that the introduction of some of the proposed additives made it possible to reduce the intensity of aging of asphalt concrete. The aging coefficient of the base composition (without additives) for 7 hours at a temperature of 150 °C was 1.40, the composition with carbon black was 2.33, with sulfur it was 1.39, and with a stabilizing additive, it was 2.74. Correlations between the values of the aging coefficient of asphalt concrete and mixtures with various additives were obtained in the CurveExpert software environment. The obtained dependencies allow us to analyze the influence of the applied additives on the processes of aging of asphalt concrete over time and rank them according to the degree of influence on the dynamics of this process.