Routes to durability and sustainability: Recycling of PmB containing RAP
Xueyan Liu (Delft University of Technology, The Netherlands)
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Abstract
Recycling of base asphalt pavement with rejuvenators or soft binders has been applied for many decades and a lot of experience has been gained. However, the high-quality recycling technique of polymer modified asphalt (PMA) has still not been sufficiently studied. The aging mechanism of PMA is complex, including the combined effects of the oxidation of bitumen and the degradation of the polymer. The current commercially available rejuvenators are designed mostly for base bitumen and not suitable for the recycling of PMA. For this reason, this research aims at designing an innovative rejuvenator specifically for the recycling of PMA. Firstly, a series of performance-based test methods, including viscoelastic properties, rutting resistance, fatigue resistance, cracking resistance, relaxation ability and aging ability, has been performed to select the appropriate source materials and to determine the optimum ratio between different components. After that, a specific SBS-based rejuvenator was found to be most effective in PMA rejuvenation. To reveal the rejuvenation mechanism, an environment scanning electron microscope (E-SEM) was utilized in investigating the microstructure of the rejuvenated binder. The results illustrated that E-SEM method can distinguish the influence of rejuvenator dosage, rejuvenator types, and addition of fresh bitumen on the morphology of aged PMB, which can help us to have a better understanding of the rejuvenation mechanism.