This article presents the results of research of processes of deformation and destruction of asphalt concrete pavements under cyclic loads. As the ground for such approach to estimation of the asphalt concrete properties served the proof that regardless of the composition and structure of asphalt concrete with an equal amount of elastic (viscoplastic) bonds possess the same relaxation ability. This situation is a significant feature of the behaviour of asphalt concrete, which opens the way for the development of certain approaches to the analysis of their properties, evaluation of reliability and durability. The promising methodology for the comparative assessment of fatigue and cyclic durability of asphalt concrete by exploring the complex set of elastic and viscoplastic bonds in their structure depending on the temperature, magnitude, and modes of action of the loads is proposed in the presented work. In the future, the establishment of patterns of behaviour of asphalt concretes with the same set of elastic bonds is allows to optimize compositions based on the principles of temperature-structural analogythat is relevant in studying fatigue and cyclic durability as well as low-temperature crack resistance and shear stability.

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The paper presents an analytical review of materials recycling for pavement dressing. Recycling or repeated usage of pavement dressing materials while making reconstruction and repair of road pavements is not considered as a new conception and it has been realized in various countries of the world since 20th century. Recycling (hot, cold) is based on methods of its execution, properties of pavement dressing materials which are subjected to processing and which influence on the quality of final material, technical and operational indices, specific economic efficiency. Investigations on the processes of structure formation, thermo-physical properties in components based on granulates of transformed pavement dressings during recycling demonstrate that regeneration makes it possible to attain 100 % recovery of material properties for road pavement base. The paper describes other factors which represent a complex of challenges concerning exterior and internal problems. These problems have arisen due to actual processes of heat and mass transfer in one layer, multi-layer systems of pavement dressings. At known coefficients of heat conductivity, steam- and mass permeability, diffusion, filtration, temperature conductivity, density of material layers etc. initial and boundary conditions it is possible to carry out optimization of heat- and mass transfer problems from bottom surface of road layer to its base (sand, bulk materials, ground). In addition to it, while taking into account development of scientific prospective direction that concerns nano-technology and creation of nano-materials for higher reliability of road dressings it is necessary to consider nanomaterial science in road-construction industry as the most actual one because when we study problems pertaining to fractional composition of all road dressing components including transfer to nanomaterials, for example, application of modified water-reducing agent based on nanostructured carbon it is possible significantly to increase physical and technological properties of asphalt concrete and concrete road dressings. The paper reveals that it is necessary to continue and expand study of physical and technical and thermophysical properties of new materials on the basis of nano-technologies with application of modified, nanostructured carbon-based plasticizer for construction-road industry because especially these additives significantly increase cement activity that leads to improvement of strength, reliability and longevity for the obtained materials.

This article presents the results of studies to optimize the composition of water dispersion of epoxy resin for the modification of RAP cold recycled mixes. The resulting water dispersion is easily combined with the bitumen emulsion and can be easily applied in the preparation of cold mixes. This kind of modification will significantly improve their reliability and durability and to closer in magnitude to the properties of hot asphalt concrete widely used for the construct of road pavements. In order to improve the efficiency of the modification process, the process of emulsification of epoxy oligomers in the presence of nonionic surfactants and further application of the obtained dispersions as a component of bitumen emulsions used for the preparation of RAP cold recycled mixes is justified. This kind of integrated approach to the selection of the composition of water dispersion of epoxy resin provided a higher level of its interaction in the formation of elastic and viscous bonds of increased strength in the formation of the structure of composites based on asphalt, bitumen emulsions and cement.

This study is devoted to finding a solution to an important problem of increasing the accuracy of assessing the fatigue stability of composites based on recycled asphalt concrete. Another problem for solving was a selecting optimal and effective ways to improve their physical-mechanical properties during modification by polymers. For experimental work, a new indicator reflecting the strength of elastic structural bonds and the specific number of viscoplastic bonds was used as a criterion for fatigue stability of bituminous-cement composites. As shown by the results of the research, fatigue (cyclic) stability has an increasing trend with the growth of these parameters. As a result of processing data from experimental studies of the structural characteristics of composites, a comparative analysis of the effectiveness of modification of cold recycled mixes by styrene acrylate and epoxy resin was performed. It was established that the composites modified with styrene acrylates have a higher relaxation ability, which is reflected in the increase in the number of cycles to failure when testing for cyclic stability. It is also noted that with an increase in the content of epoxy resin in the composition of mixes, the increase in stiffness occurs much more strongly in comparison with an increase in their relaxation ability. At the same time, the efficiency of modification of cold recycled mixes with epoxy resins is significantly increased with the preliminary preparation of asphalt granulate (RAP), for example, during its plasticization with soy epoxidized oil. This work also allowed us to outline some areas of development of the methodological foundations for assessing the cyclic and fatigue stability of composites based on cold recycled mixes. Keywords Fatigue resistance • Recycled asphalt pavement (RAP) • Modified cold reclaimed mixes • Styrene-acrylic water dispersion • Water dispersion of epoxy resin • Epoxidized soybean oil * Vitali Zankavich,