Influence Reclaimed Asphalt Shingles on the Physicochemical and Rheological Properties of Road Bitumen

The article presents the results of a study on 50/70 paving-grade bitumen modified with the bitumen recovered from two types of asphalt shingles: post-consumer asphalt shingles (TOAS) and manufacturing waste asphalt shingles (MWAS) at three dosage levels (15%, 30%, and 45% <i>w</i>/<i>w</i>). The evaluation included the basic properties of bitumen-its penetration and softening point-as well as rheological properties, such as its viscosity, fatigue life determined by the LAS method, and rutting resistance assessed using the MSCR test and FTIR analysis. In both cases, the results showed that an increase in the stiffness of the base bitumen was observed. An improvement in rutting resistance was also recorded, as evidenced by the reduction of J_nr3.2, along with an increase in fatigue life. A stronger stiffening effect was found in the case of the TOAS-derived bitumen, which is related to aging processes occurring during its service life. This suggests that the maximum allowable content of the additive should depend on the source of the reclaimed asphalt shingles, with MWAS being applicable in larger amounts without excessive deterioration of bitumen performance. The key contribution of this study is the demonstration that the MWAS and TOAS additives cannot be treated equally, as each affects the base bitumen differently.