Fatigue resistance of modified cold reclaimed mixes with 100% content of recycled asphalt pavement (RAP)

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.