Use of high polymer-modified bitumen for compensating the presence of degraded SBS in the blends of aged and virgin polymer-modified bitumen: a laboratory study on the binder scale

Hot recycling of reclaimed asphalt pavement (RAP) in new hot mix asphalt (HMA) including polymer-modified bitumen (PmB) is problematic because the SBS in the RAP would be degraded or absent. To avoid this issue, the use of highly modified asphalt (HiMA) with an increased SBS content has been recently proposed. In the present study the rheological and performance behaviour of a blend including 50% of HiMA and 50% of RAP bitumen was evaluated in comparison with a reference virgin PmB and a blend including 50% of PmB and 50% of RAP bitumen treated with an ordinary recycling agent. The blend of HiMA and RAP bitumen showed an excellent performance in terms of resistance to permanent deformation and fatigue behaviour, as the excess of SBS in the HiMA entailed a noticeably marked elasticity of the bituminous blend. However, ageing caused a significant decrease of the performance for the HiMA + RAP blend.