Identification of Suitable Parameters for Quantitative Comparison of Bitumen with Similar Grades

With India importing more than 35% of its bitumen demand, there is a significant variation in the cost of bitumen in the international market. There is a need to identify suitable parameters that can help in selecting the right bitumen for a given viscosity grade (VG). In this study, the physical, rheological, and chemical characteristics of bitumen(s) acquired from different sources and falling under the same viscosity grade were explored under unaged, short-term aged, and long-term aged conditions. Two grades of bitumen (VG30 and VG40) obtained from three sources (P1,J1,I1 and P2,J2,I2) were evaluated. Though the binders obtained from different sources were found to satisfy the criterion as per Indian specification, they showed dissimilar short- and long-term characteristics. The bitumen(s) had unique temperature susceptibility and aging indices, which revealed the effect of the source on the performance of the binders. The difference in short- and long-term aging indices obtained from rheological data was in agreement with the FTIR results and asphaltene–maltene ratio(s). This study recommends using the short-term aging index (STAI) and long-term aging index (LTAI) obtained from frequency sweep data for selecting the appropriate source of bitumen. Aging indices at lower loading frequency and high in-service temperature should be selected for comparing the binders. Future study should focus on establishing limits of aging indices for characterization and selection of bitumen for practical conditions.