Application of innovative bitumen for recycling in asphalt concrete containing reclaimed asphalt pavement

Bitumen, as one of the oldest construction materials, has significant recycling potential, which makes it both environmentally friendly and in line with the principles of the circular economy. Although the recyclability of bituminous materials is widely recognised, the discussion continues on the possibility of increasing the efficiency of using Reclaimed Asphalt Pavement (RAP) in asphalt mixtures. The article presents the results of research on the application of a new type of experimental bituminous binder dedicated to recycling in asphalt concrete. The study included experimental tests of asphalt concrete for the binder course with variable RAP contents up to 30%, using a cold feeding process. Both laboratory test results and the findings from a trial road section are presented. For comparison, conventional road bitumen 35/50 was used as the reference binder, while an innovative recycling-dedicated binder 35/50 exp was applied as the experimental binder. The mixtures were subjected to classification testing as well as extended testing of long-term ageing resistance. The research confirmed that the experimental 35/50 exp bitumen, dedicated to recycling applications, enhances the compactability of mixtures containing 20-30% cold-feed RAP and improves the ageing resistance of asphalt mixtures. It was demonstrated that the action of experimental bitumen dedicated to recycling in mixtures containing RAP occurs in several stages: during production and laying, experimental bitumen supports compactability, while in the long term, it contributes to improved ageing resistance.