Laboratory evaluation of the effect of rejuvenators on the interface performance of rejuvenated SBS modified bitumen mixture by surface free energy method

Abstract

The surface free energy and related parameters of asphalt binder affect the wettability of asphalt binder to aggregate and its moisture sensitivity. In this research, the surface free energy and related parameters of SBS modified bitumen (SMB) after aging/rejuvenating were tested and analyzed. And then based on this data, the effect of common rejuvenator cashew shell oil and active isocyanate rejuvenators on the water damage resistance and moisture sensitivity were evaluated and predicted. The results indicated that the surface free energy of SMB decreased after aging, while rejuvenators all can enhance the surface free energy. The cohesion work of aged SMB increased after rejuvenating, and the adhesion work between aged SMB and granite were enhanced by 12.4% at least with the addition of rejuvenators, namely, rejuvenators can improve its cracking resistance and interface stability, and active rejuvenator hexamethylene diisocyanate showed the best performance. Water boiling test showed that the adhesion grade of SBS modified bitumen on granite decreased from adhesion grade 5 to adhesion grade 3 after aging, while active rejuvenators can bring the adhesion grade of aged SMB on granite to the original level. This paper would be helpful to understand the moisture resistance mechanism of rejuvenated SBS modified asphalt mixture with active regeneration technology.