The effects of rejuvenating agents on recycled aged CRM binders

The recycling of asphalt pavements containing crumb rubber modifier (CRM) modified binders is increasing in areas having these types of asphalt pavements more than 10 or 15 years old. The performance and physical and rheological properties of the blends of aged CRM binders containing rejuvenating agents due to the presence of CRM have not been considered in detail. In this study, two CRM binders and one control binder of PG76-22 were artificially aged and then used as recycled materials by adding different rejuvenating agents, i.e. a rejuvenator and a softer binder. The properties of the blends of the three aged binders containing various percentages of the rejuvenating agents were evaluated using Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR) as well as viscosity tests. The test involved three different aging states of the blends: original, RTFO residual and RTFO+PAV residual. Results from this study show that: (1) the aged CRM binders can be rejuvenated back to a targeted PG grade; (2) the rejuvenating agents investigated are effective in changing the properties when used with the aged CRM binders; (3) the presence of crumb rubber in the modified binders enhances their aging resistance; (4) the target grade is more easily reached by adding the rejuvenating agents to the aged CRM binders rather than the aged control PG76-22.