Modification of lower viscosity grade bitumen into higher viscosity grade bitumen via glycerol and maleic anhydride-based polyester

In this study, a synthetic polyester is utilized to upgrade low-viscosity grade bitumen into higher-viscosity grades. A polycondensation of maleic anhydride (M) and glycerol (G) monomers was conducted under optimized temperature, varied time, and molar ratios, resulting in the synthesis of 16 different polyesters.One of the polyester M3G1H5 (M: maleic anhydride, G: glycerol, and H: time) was identified as the most effective polyester for bitumen modification due to its optimal viscoelastic properties. This specific formulation resulted in three polyester-modified bitumens blended with base bitumen (VG10) in 6–15 wt% concentrations. The modified bitumens, rigorously tested as per ASTM standards, significantly improve softening point, viscosity, and ductility. Remarkably, two formulations met the VG30 and VG40 specifications as per IS 73:2013, aside from the absolute viscosity requirement at 60 °C. Their superior rutting and deformation resistance was confirmed by rheological analysis, indicating polyesters' role in boosting performance. Furthermore, the synthesized modified bitumen was subjected to short-term aging using a rolling thin film oven test (RTFOT), revealing that the polymer was uniformly distributed in the bitumen medium and retained the viscoelastic properties of the bitumen. The suitability of different bitumen variants across varying environmental and traffic conditions was evaluated using the Multi-Criteria Decision Analysis (MCDA), and it was concluded that polyester-modified bitumens are suitable for various climatic conditions and traffic situations.These findings highlight the pivotal role of the synthesized polyester in elevating lower-grade bitumen to high-performance grades suitable for modern construction demands, thereby indicating a promising avenue for bitumen modification.