Rheological Assessment of a Polymer-Modified Bitumen with 30% Recovered Bitumen for Asphalt Mix Recycling

Polymer-modified bitumen performs better at different temperatures and loading conditions than pure bitumen. Therefore, using this type of bitumen in recycled asphalt mixtures containing reclaimed asphalt (RA) material can lead to a better performance than pure bitumen. However, the presence of a very hard and aged binder in the RA, especially for high RA incorporation ratios, may increase bitumen stiffness and negatively affect the performance of the polymer-modified bitumen. Therefore, it is essential to know the effect of recovered binders on the characteristics of polymer-modified bitumen. This study investigated the characteristics of an elastomeric polymer-modified bitumen combined with 30% recovered bitumen and a rejuvenating agent using penetration grade, softening point, viscosity, and elastic recovery tests. By analysing the master curves obtained from dynamic shear rheometer (DSR) tests in a wide range of temperatures and loading frequencies, the rheological characteristics of the same bitumen were also evaluated and compared to commercial bitumen samples (i.e., polymer-modified bitumen and pure 70/100 pen grade bitumen). The conventional test results showed that the recovered bitumen from RA increases the stiffness of polymer-modified bitumen even with a rejuvenator. However, the DSR test results showed that it is possible to maintain the rheological characteristics of polymer-modified bitumen combined with 30% recovered binder and a rejuvenator.