Rejuvenating aged asphalt using surfactant-foaming warm recycling technology

Warm mix recycling technology can accommodate higher content of reclaimed asphalt pavement (RAP) material, contributing to environmental benefits. However, it is still unsure which warm mix technology works best with the RAP. In this study, a combination of the foaming process and surfactant additive was used to recycle aged asphalt. By applying a series of rheological and chemical tests, the performance of regenerated aged asphalt using surface-activated foaming technology was evaluated. Besides, the regeneration effect was compared with that of bio rejuvenator and soft asphalt. It was found that the surfactant could recover the aged asphalt to a certain extent, but it was still difficult to recover it to the original level. The content of the aged binder had a great influence on the performance of recycled asphalt. When the content of aged asphalt was less than 50%, the softening and viscosity reduction effect of foamed Evotherm DAT was the best, and Evotherm DAT and soft asphalt were superior to bio rejuvenators in improving fatigue performance. The micro characteristic indexes such as sulfoxide index, GPC parameters, and bee-shaped area ratio can effectively explain the changes in engineering properties of asphalt binder in aging and regeneration.