Recycling characteristics of polymer modified asphalt

The aged polymer modified asphalt (abbreviated as PMA) was recycled with two methods which were adding fresh PMA and adding recycling agent to investigate the recycling characteristics of PMA. The performance of the recycled PMA was evaluated systematically with a variety of indices, including penetration, softening point, ductility, viscoelasticity and stiffness. The results indicate that the performance of recycled PMA mixing with the fresh PMA or recycling agent with the optimistic content is improved and can meet the technical requirements. The performance of recycled PMA has good correlation with the content of the fresh PMA or recycling agent. However, the difference of the recycling characteristics between PMA and base asphalt is significant because of the damage of the SBS crosslink structure. The softening point of the PMA recycled by recycling agent does not return to the original extent though it can still meet the demand of the national specification. It is proved that the viscoelasticity characteristics of recycled PMA are different from the original PMA by the Dynamic Shear Rheometer (DSR) tests. In the high temperature range (over 60°C), the elastic property of recycled PMA is lower than that of original PMA, and it is relatively close to base asphalt. In the low temperature range (below 60°C), the viscoelasticity characteristics of the recycled PMA and original PMA are consistent.