Evaluation of Real Operating Conditions and Actual Temperature Changes when Modeling the Composition of Asphalt Concrete Structural Layers

All types of improved pavements operate under extreme conditions in terms of loads and temperatures. The degree of these influences is modeled by standardized tests, which, as a rule, reproduce only the load at a constant temperature. Based on these results, requirements are imposed on the materials of structural layers that do not fully reflect a number of features of their performance in road pavements. In fact, the main temperature effects and temperature-physical changes occurring in asphalt concrete are not taken into account, which can lead to insufficient durability and reliability. These changes include the material's response to temperature fluctuations, which can cause infrastructural changes and lead to increased cracking and poor performance. In our work, we conducted research to determine the thermophysical parameters of the material of the upper structural layers of road pavement, such as the coefficients of thermal conductivity, heat capacity, and thermal expansion (compression). A distinctive feature of our experiments was the tracking and determination of thermophysical indicators in the dynamics of the process of temperature changes. The article presents the results of local experimental studies of prototypes of asphalt concrete to determine the coefficients of thermal linear expansion, thermal conductivity and heat capacity at given temperature differences. Given the importance of these characteristics, it is necessary to reconsider the requirements for materials of structural layers in order to ensure that realistic operating conditions are simulated and actual temperature changes are taken into account. The main result of the research can be considered the developed methodology for further work, in which it is planned to take into account the gradient and rate of temperature change, the size of the stone aggregate, and the change in rheological characteristics depending on the temperature change.