Abstract
Polymer additives are used to improve the properties of road bitumens including their oxidative resistance. However, their usage as anti-oxidative materials remains relatively unclear. This study aims to investigate the changes in the morphology and the rheological response of polymer modified bitumens used in road pavement construction caused by ageing. An elastomer (radial styrene butadiene styrene, SBS) and a plastomer (ethyl vinyl acetate, EVA) polymer were mixed with one base bitumen at three polymer concentrations. The bitumens were RTFO and PAV aged. The morphology of the bitumens was captured by fluorescence microscopy while the rheological properties were measured by means of the multiple stress creep and recovery (MSCR) test. The results show that the morphology of the SBS modified bitumen degrades with ageing as a function of polymer concentration and dispersion, with higher dispersion being more resistant. The morphology of the EVA modified bitumen has a low ageing susceptibility irrespective of polymer concentration. The MSCR response of EVA modified bitumens does not differ from that found for unmodified bitumen, where the hardening produces a decrease in the non-recoverable compliance. In the case of SBS modified bitumen, the degradation of the polymer backbone affects the bitumen hardening as much as the polymer phase dispersed and networked in the bitumen phase. Furthermore, in the case of the elastomer, the average percent recovery is in agreement with the variation of the morphology with ageing. Therefore, the use of the average percent recovery as a valuable rheological index of the integrity of the polymer network can be advocated.
Highlights
In the past few decades, the demand for transportation has increased significantly and road infrastructure is currently challenged by increased traffic
The bitumens were laboratory short-term aged in the rolling thin film oven (RTFO) and long-term aged in the pressure ageing vessel (PAV) by following the AASHTO R28
This section includes the description of the morphology of the bitumens at different levels of ageing and the results of the multiple stress creep and recovery (MSCR) test
Summary
In the past few decades, the demand for transportation has increased significantly and road infrastructure is currently challenged by increased traffic. Polymer modification aims to stiffen the bitumen and to increase its elasticity at high pavement temperatures; to decrease the temperature susceptibility; to maintain sufficient levels of workability during mix production and laying, and to provide lower levels of stiffness at intermediate and low pavement temperatures In addition to these modifications, polymermodified bitumens (PMBs) should be stable at storage and ageing resistant [4]. The success of the modification depends on the capability of the polymer swelling in the bituminous phase by absorbing the bituminous fractions and thereby having higher compatibility, and in the maintaining its own structure Such conditions occur with an adequate degree of swelling and solubility of the polymer within the bitumen phase [5]. Concerning the affinity, the lighter components of the bitumen appear to be more compatible than the heavier molecules
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
