Recycled Asphalt Shingle Binder Characterization and Blending with Virgin Binders

Abstract

In addition to reclaimed asphalt pavement (RAP), recycled asphalt shingles (RAS) have been accepted and used by different transportation agencies in recent years. However, limited information on RAS binder characterization and blending with virgin (and RAP) binders is available in the literature partially because of the limitations of regular dynamic shear rheometers (DSRs) and bending beam rheometers (BBRs) to test this type of material. This paper first validated the applicability of the existing asphalt binder extraction and recovery procedures to extremely stiff RAS binders. Then a variety of tear-off asphalt shingles (TOAS) and manufacture waste asphalt shingles (MWAS) were extracted, recovered, and characterized with a high-temperature DSR and a BBR. It was found that TOAS binders were much stiffer than MWAS binders. Furthermore, this paper investigated the blending among virgin, RAP, and RAS binders. The results indicated that the virgin–RAS binder blending was nonlinear, unlike the well-known virgin–RAP binder linear blending. However, for practical application, the linear blending chart can still be used for estimating continuous grades of both virgin–RAS blended binders and virgin–RAP–RAS blended binders if the RAS binder is limited to 30% of the total binder. Additionally, compared with TOAS binders, MWAS binders had much less impact on properties of blended virgin–RAS binders. Therefore, it was necessary to differentiate MWAS from TOAS in the mix design process and to have different upper limits on maximum RAS binder replacement for MWAS and TOAS.