Development on recycling, aging simulation and regeneration methods of reclaimed styrene-butadiene-styrene modified asphalt

Abstract

To develop the recycling, aging simulation and regeneration methods of reclaimed styrene-butadiene-styrene (SBS) modified asphalt, the centrifugation method of reclaimed asphalt pavement (RAP) was first optimized. Then the relationship between asphalt performance indexes and aging duration of rolling thin film oven test (RTFOT) was studied. Also, two regeneration methods of reclaimed asphalt were discussed and the regeneration mechanism was revealed by fluorescence microscope, Fourier transform infrared spectrometer and X-ray diffraction tests. Results indicate that RAP should be soaked by the trichloroethylene for 4 times and each time is for 30 min. The developed method for removing the mineral powder in the extraction solution through twice statically keeping and separating the extraction solution is feasible to replace the conventional method using high speed centrifuge. Afterwards, a practicable aging simulation method of SBS modified asphalt using the delayed RTFOT is developed, which shows obvious advantages in test efficiency and result accuracy. Moreover, the SBS modifier content of 4 wt% and the proportion between fresh SBS modified asphalt and reclaimed asphalt of 2:1 are proposed to reconstruct a network structure in rejuvenated asphalt I, improving the high-temperature thermal stability and low-temperature cracking resistance. The regenerant content of 9 wt% is recommended to add in reclaimed asphalt, increasing the content of light components in rejuvenated asphalt II and activating the secondary modification effect of residual SBS modifier, so that the low-temperature cracking resistance and anti-fatigue performance of rejuvenated asphalt II are improved. Finally, the content of aged products including sulfoxide, ketones and carboxylic acids in the rejuvenated asphalt I and II samples are decreased, while the interlayer spacing and crystallite size are increased. The properties of reclaimed asphalt are regenerated using the developed regeneration method I and II. This study develops new recycling, aging simulation and regeneration methods of reclaimed SBS asphalt.