Comparative Performance of Asphalt Binder Modification Using Reacted and Activated Rubber (RAR) and Depolymerized PET Oligomers: Rheological, Mechanical, and Sustainability Perspectives

Description

Comparative Performance of Asphalt Binder Modification Using Reacted and Activated Rubber (RAR) and Depolymerized PET Oligomers: Rheological, Mechanical, and Sustainability Perspectives

Nailton Silva Costa Mafra¹, Leticia Cardoso Nunes², Márcio Muniz de Farias³

PhD Student¹, University of Brasilia, Brazil

PhD², University of Brasilia, Brazil

Professor³, University of Brasilia, Brazil

nailton.mafra@aluno.unb.br

ABSTRACT. This comparative study investigates the modification of asphalt binders using two innovative approaches: Reacted and Activated Rubber (RAR) and depolymerized polyethylene terephthalate (PET) oligomers, focusing on their effects on binder performance for flexible pavements. Drawing upon experimental data from recent Brazilian research, the analysis systematically evaluates the rheological, physical, and mechanical enhancements provided by each modifier, as well as their implications for sustainability and practical application in road construction.

RAR, a fourth-generation asphalt-rubber technology, is produced by combining conventional asphalt, finely ground recycled tire rubber, and an Activated Mineral Binder Stabilizer (AMBS). This composition simplifies manufacturing, allowing for room-temperature storage and eliminating the need for specialized blending equipment. The RAR process enables higher rubber content and improved binder elasticity, resulting in increased dynamic shear modulus, reduced temperature susceptibility, and enhanced fatigue resistance. Laboratory tests demonstrate that RAR-modified binders exhibit improved performance under repeated loading, with greater durability and resistance to cracking and rutting.

In contrast, PET oligomer modification involves the chemical recycling of post-consumer PET waste into oligomers with molecular weights of approximately 500 g/mol, which are then incorporated into asphalt binder using high-shear mixing. PET-modified binders show a marked increase in stiffness, as evidenced by significant reductions in penetration values and systematic increases in softening points. The thermal stability of PET oligomers ensures their compatibility with asphalt mixing temperatures, while rheological tests reveal improvements in high-temperature performance grade (PG), rutting resistance, and fatigue life.

Both modification strategies contribute to sustainability: RAR utilizes tire waste, reducing landfill burden and promoting circular economy practices, while PET oligomer modification addresses the environmental challenge of plastic waste by valorizing it in high-value infrastructure applications. The study highlights that RAR offers practical advantages in terms of logistics and ease of implementation, whereas PET modification excels in enhancing high-temperature and fatigue performance. The choice between these technologies should be guided by project-specific requirements, available infrastructure, and environmental priorities. Ultimately, the integration of RAR and PET oligomers into asphalt binder technology represents a significant step toward more durable, resilient, and sustainable pavements, supporting the development of advanced materials for modern road networks.

KEYWORDS: asphalt binder, Reacted and Activated Rubber (RAR) and depolymerized polyethylene terephthalate (PET) oligomers