Non-recoverable creep behavior and micro-structural analysis of recycled bitumen containing aged bitumen and TLA modified bitumen

Abstract

TLA modified bitumen can effectively improve the rutting resistance of asphalt mixture, and the application of reclaimed asphalt pavement (RAP) in TLA modified bitumen needs to be further improved. In order to further improve the rutting resistance of bitumen, and to more comprehensively evaluate the high temperature resistance characteristics, a variety of recycled bitumen containing different contents of aged bitumen and TLA modified bitumen were prepared. Then, based on the penetration grades (PG) analysis and multiple stress creep recovery (MSCR) tests, the effects of temperature, time, aging, loading stress and aged bitumen content on the non-recoverable creep behavior of recycled bitumen were evaluated. Finally, the enhancement mechanism of the rutting resistance was analyzed from the aspects of morphology and modulus by atomic force microscopy (AFM). Results indicate that recycled bitumen with a higher content of aged bitumen can show better creep recovery characteristics under constant temperature changes, and is less susceptible to aging and high stress. Under the same traffic load conditions, the service environment of recycled bitumen can be increased by 6 ℃ for every 20% increase in the aged bitumen content. Aged bitumen can help TLA modified bitumen better accumulate heavy components, enhance the overall surface roughness and material stiffness, which can contribute to the better resistance to the rutting deformation.