Investigation on rheological properties of bitumen based on rheological parameters of maltenes

Previous research studies have indicated that each bituminous component plays a different role in rheological properties of bitumen. However, a few literature studies focus on rheological parameters of bitumen at component level. This paper aims to investigate the intuitive influence of rheological parameters of maltenes on rheological properties of bitumen. Saturates, aromatics, resins and asphaltenes (SARA) were firstly separated from two base bitumens and Styrene-butadiene-styrene (SBS)-modified bitumen. Dynamic shear rheometer (DSR) was applied to characterise the rheological properties of three bitumens and their maltenes. Temperature and frequency sweep tests were conducted to obtain six rheological parameters, including complex modulus, phase angle, complex modulus index, rutting factor, fatigue factor and rheology cracking index. The results indicate that the elasticity of base bitumen in low-temperature stage is mainly provided by resins and aromatics compared with the sole contribution of aromatics in SBS bitumen. The promotion effect for enhancing anti-rutting ability of resins in base bitumen is superior to that of SBS bitumen. Saturates, with a rutting factor of less than 1 kPa, lead to a passive effect on deformation resistance at higher temperatures of bitumen. Maltenes show a different contribution rate of improvement of fatigue resistance in a descending order of saturates, resins and aromatics. Aromatics with superior cracking resistance contribute to the enhancement of ductility for bitumen in contrast to resins with a larger rheology cracking index. The intuitive analysis on maltenes will facilitate further investigation of the interaction mechanism for bitumen modification and rejuvenation so as to enhance rheological properties of bitumen.