Investigation of rejuvenation mechanisms of reclaimed asphalt rubber pavement through mortar tests

ABSTRACT

Conventional rejuvenation methods recover the rheological properties of aged bitumen by adding rejuvenators to supplement the content of light fractions of bitumen. However, these methods cannot fully restore the microstructure and advantages of aged asphalt rubber (AR) binder due to the dissolution of rubber particles. Aiming at discovering a more suitable rejuvenation strategy for reclaimed asphalt rubber pavement (RARP), this study investigates the rejuvenation mechanisms of RARP through a series of chemical and rheological tests at the mortar level. A chemistry-based method was proposed to estimate the rubber dissolution in RARP mortar. AR mortars containing 40% of RARP mortar (RARP40%) were prepared. Three rejuvenation schemes were adopted for RARP40%, namely recovering the light fractions, supplementing the swelling rubber content, and both recovering and supplementing, respectively. The results indicate that adding rejuvenator only can effectively soften the aged RARP binder but it fails to slow down the rheological evolution of RARP40% mortar in the secondary aging. The incorporation of AR binder with extra rubber content notably improved the aging resistance but significantly compromised the workability of RARP40% mortar. The compound rejuvenation scheme was the optimum solution that balanced the rejuvenation effectiveness, aging resistance and workability.

KEYWORDS:

• Recycling
• tyre rubber
• reclaimed asphalt rubber pavement
• rejuvenation
• mortar
• rheological properties

Acknowledgements

The funding support from the Research Grant Committee RGC Germany/Hong Kong Joint Research Scheme: Aging and Recycling Mechanisms of Sustainable Asphalt Rubber Pavements (G-PolyU506/20) is sincerely appreciated.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Research Grants Council, University Grants Committee: [Grant Number G-PolyU506/20].