Effects of reclaimed asphalt binder on rheological properties and cohesion energy of crumb rubber modified binder

Reclaimed asphalt pavement (RAP) material is widely used for construction of sustainable pavements. Inclusion of RAP binder with crumb rubber modified (CRM) binder can provide added advantage in terms of reduced materials cost and solution to waste disposal problem. However, addition of aged of RAP binder to stiffer CRM may discourage the use of such combination. In the present study, it was observed that addition of RAP did not significantly change viscosity of CRM binder, which motivated the authors to evaluate rheological performance of blended binders. CRM binder was blended with different percentages (0, 15, 25 and 40%) of RAP. The effect of RAP on basic properties (penetration, softening, ductility, elastic recovery) of CRM binder was investigated. In addition, Superpave test protocol was utilized to evaluate change in rutting and fatigue and performance grade of CRM binder. Further, change in surface free energy of CRM binder after addition of RAP was measured using sessile drop method. Effects of RAP on activation energy, aging index and temperature susceptibility of CRM binder are also reported. The results showed that addition of RAP contributes stiffening nature of CRM binder; however, a lower percentage of RAP may still be considered beneficial. Higher percentage of RAP may result in poor cohesive energy and weak compatibility with aggregates.