What is asphalt rejuvenation?
Asphalt rejuvenation is the process of using a recycling agent to restore the functional performance and balance the physical properties of aged binder found in reclaimed asphalt pavement (RAP). Effective asphalt rejuvenation with a proper recycling agent results in a bitumen that meets the specifications and delivers a performance that is similar or equivalent to virgin bitumen.
What is the difference between asphalt rejuvenators and asphalt recycling agents?
Over the recent years, the asphalt and bitumen standards community has adopted the term asphalt recycling agent as the preferred terminology. However, frequently, the terms asphalt rejuvenator and asphalt recycling agent are used interchangeably to describe an additive that is used to restore the functional performance and balance of properties of aged binder.
What are the different types of rejuvenators / recycling agents?
There are a variety of different asphalt rejuvenators / recycling agents available in today’s marketplace. Most are proprietary formulas. They may include waste streams, petrochemical oils, Re-refined Engine Oil Bottoms (REOBs) and bio-based oils or a combination.
What are the advantages of bio-based asphalt rejuvenators / recycling agents?
Bio-based asphalt rejuvenators / recycling agents are on-purpose manufactured oils and blends that are derived from environmentally sustainable sources. They are engineered specifically for the rejuvenation of aged asphalt. They have high flash points, are stable in manufacturing and storage operations, typically provide better dosage efficacy over other rejuvenators, and offer safer chemistries for more environmentally friendly solutions.
Why is there a need for asphalt rejuvenation?
When roadways age, in order to repair or replace a damaged section, the top layers are milled off. This material is called “Reclaimed Asphalt Pavement” or RAP. In the past, RAP was primarily discarded and ended up in landfills. However, there are valuable materials in RAP – both stone / aggregate, as well as bitumen. Asphalt rejuvenation is the process of bringing new life to this RAP, restoring the aged bitumen, reusing the valuable materials in RAP, and keeping it out of landfills. The old roads of the past can be transformed into the new roadways of today and tomorrow with rejuvenation.
What are the benefits to asphalt rejuvenation?
There are two over-riding benefits to asphalt rejuvenation. Using a recycling agent and RAP is better for the environment. RAP is kept out of landfills, and the aged bitumen is restored and able to be re-used. Old and damaged highways become the mines of the future.
The second is the economic benefits. Using RAP and an asphalt rejuvenator / recycling agent offers the opportunity to reduce overall mix cost.
What are the negatives to asphalt rejuvenation?
Done correctly, there are no known downsides to using rejuvenated asphalt in mixes.
Are asphalt rejuvenators / recycling agents the same thing as a softener?
No. Asphalt rejuvenators /recycling agents are not the same as softening agents. Asphalt rejuvenators can function as softening agents, but all softening agents are not rejuvenators or recycling agents. Softening agents, also referred to simply as softeners, are used to adjust the grade (Penetration, PG Low Grade, Viscosity) of hard virgin bitumens. But the asphalt in RAP is much harder than virgin bitumen. RAP bitumen is aged and oxidized to a much greater extent. Asphalt rejuvenators / recycling agents not only soften the bitumen, but they also restore key properties and functionality of the aged binder and deliver long term performance and durability to roadways. Lastly, asphalt rejuvenators / recycling agents are typically much more dosage-efficient than softeners.
Are asphalt rejuvenators / recycling agents the same thing as a seal coat?
No. Asphalt rejuvenators / recycling agents restore the balance of properties in the entire mix, across the entire thickness of the roadway pavement. A seal coat is a very thin layer applied across the top of an existing roadway. A seal coat is designed to provide a measure of impermeability, to seal in imperfections, in order to extend the life of a roadway and may provide better ride characteristics. It may contain a rejuvenator, but a seal coat does not provide rejuvenation across the entire thickness of the pavement.
Are asphalt rejuvenators / recycling agents only used in a Hot Mix?
No. Asphalt rejuvenators / recycling agents can be used in hot mixes, rejuvenating emulsions, hot spray applications, cold-in-place recycling, full-depth reclamation, pothole patching mixes and for road maintenance applications. Asphalt rejuvenators / recycling agents can be used wherever RAP materials are involved.
