Empirical, rheological and chemical properties of recycled binder blends with rejuvenators at different ageing levels

Abstract

The use of Reclaimed Asphalt (RA) into new asphalt mixtures becomes an inevitable step for sustainable infrastructure. Saving natural, non-renewable materials, such as bitumen and aggregates, the asphalt industry is moving forward with more recycling. Although asphalt is a 100% reusable material, high recycling rates are not yet easily achievable due to many limitations, going from technical specifications through RA properties to asphalt plant capabilities. The rate of RA, which may be used within a new asphalt mixture, depends on many aspects: variability, moisture and fines contents, presence of polymers, brittleness of aged binder, etc. The latter is directly linked to the degree of the RA binder ageing. As higher RA content increases the asphalt mixture stiffness, the material becomes more brittle and prone to cracking. The use of recycling additives is taking recycling to the next level by solving these issues. With the growing need of the industry for asphalt recycling agents, many products have appeared on the market with different effects. In this study, three asphalt recycling agents (two industrial and one alternative) were used as rejuvenators. Blends with50% of rejuvenated RA binder (RAb) and virgin binder were subjected to different ageing levels: short (RTFOT), long (PAV for 20h) and prolonged (PAV for 60h). After each ageing level, physical, rheological and chemical properties were evaluated addressing the ageing behaviour of the additives used. Testing results showed that one industrial additive lost almost all its properties after prolonged ageing, while the other additives showed comparable results with the second industrial product.