Introduction. Asphalt concrete is the most common material for arranging road pavement layers. The significant advantages of asphalt concrete include high performance characteristics, relatively high technical indicators, suitability for regeneration, etc. At the same time, asphalt concrete also has disadvantages, one of which is the significant dependence of strength and deformation characteristics on ambient temperature. Problem statement. Currently, there are no clear criteria for the selection of bitumen in Ukraine that would take into account the conditions of asphalt concrete in the design of pavement structure, but the first steps are already being taken in this direction. The purpose of this work was to practically determine the required properties of bitumen in accordance with the previously proposed algorithms. Objective. Practical determination of the required properties of bitumen in accordance with the previously proposed algorithms. Materials and methods. Analysis of the algorithm for determining the required properties of bitumen, climatic conditions of asphalt concrete and calculation of the required bitumen grade when designing a pavement structure. Results. Suggestions for improving the algorithm for selecting bitumen when designing a pavement structure are provided. An analysis of the climatic conditions of asphalt concrete operation and the calculation of the required bitumen grade according to performance indicators when designing a pavement structure for a conditional road section were performed. A system for selecting bitumen by penetration classification based on established performance indicators is proposed. Conclusions. The proposed algorithm for determining the required bitumen grade when designing a pavement structure can be used to determine the bitumen grade both by performance and penetration classification.
Introduction. Asphalt concrete is the most common material for paving layers of roads. Significant advantages of asphalt concrete include high operational characteristics, relatively high technical values, suitability for regeneration and more. At the same time, asphalt concrete has its drawbacks, one of which is the significant dependence of strength and deformation characteristics fronm the ambient temperature. The essential role in the temperature properties of asphalt concrete is played by bitumen, the quality of which is currently evaluated by standard indicators in accordance with the penetration system. The properties of bitumen can be more accurately and objectively evaluated by rheological indicators (viscosity and cohesion) or by operational ones, which are determined depending on the climatic conditions of asphalt concrete layers. Therefore, there is a need to analyze the climatic conditions of asphalt concrete in the pavement structure. Problem statement. Today in Ukraine a penetration system uses for evaluation of bitumen properties that determines the type of bitumen and the corresponding characteristics. About 30 years ago, the United States developed a system for evaluation of bitumen operational characteristics, which combines climatic conditions and transport loadings. This approach allows to choose bitumen for assigned designing combination of high and low temperatures. Evaluation of the appropriate climatic conditions of asphalt concrete in Ukraine will allow to develop zoning on the basis of which it is possible to make the optimal choice of bitumen, which would increase the durability of asphalt concrete and pavement structure in general. Purpose. Creation of bitumen selection system during designing of pavement structure, considering the ambient temperature, transport loadings, traffic intensity, level of reliability and location of asphalt concrete in the pavement structure. Materials and methods. Collection of climatic data regarding ambient temperature according to the data of meteorological stations located in regional centers of Ukraine for the period from 2005 till 2020 and determination of the needed operational properties of bitumen. Results. The zoning of the territory of Ukraine according to the climatic conditions of asphalt concrete considering the ambient temperature, transport loadings, traffic intensity, level of reliability and location of asphalt concrete in the pavement structure is developed. Conclusions. Development and introduction of zoning of the territory of Ukraine according to the operational conditions of asphalt concrete and bitumen selection system according to operational indicators will prevent the formation of destruction in the form of plastic deformations, cracks and low-temperature cracks and thus will increase the durability of asphalt concrete. Keywords: asphalt concrete, bitumen, binding layer, operational properties, pavement structure, pavement layer, upper layer of foundation.
Introduction. Asphalt mixtures are the most widely used road construction material for the arrangement of the top layers of road pavement. Asphalt mixtures are also used to arrange airfield runways, bridges deck surfacing, streets, pedestrian and cycle paths, etc. There is a large number of asphalt mixtures types that differ by grading, the largest nominal aggregate size, crushed stone content, crushed and uncrushed sand content, quality of components, and viscosity of the bitumen binder. Problem statement. The national method for asphalt mixture design is very similar to the Marshall method and the Superpave method in terms of determining the optimal bitumen binder content by the bulk properties of asphalt concrete. The only difference is that, according to the Marshall and Superpave methods, the optimal bitumen content is the one with an air pore content of 4.0 %. However, in accordance with the national method, the design air pore content varies depending on the type of asphalt mixture. A significant innovation of the Superpave method is the determination of asphalt performance indicators, such as rutting resistance, crack resistance, and resistance of the material to fatigue cracking. Apparently, these methods should also be implemented in Ukraine over time. Purpose. Analysis of the methods for asphalt mixtures design. Materials and methods. Analysis of literature sources on various methods of asphalt mixtures design. Results. The analysis of literary sources on different methods of asphalt mixtures design was carried out. Conclusions. The use of different methods of asphalt mixtures compaction can lead to the production of asphalt concrete with different volumetric properties, which will affect both the optimal bitumen content and the performance of asphalt concrete, thus further research should be aimed at defining the effect of the compaction method on the volumetric properties of asphalt concrete and their relationship with the production compaction of asphalt mixtures.
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