Asphalt Rejuvenators

Recycling Agents (RA) are liquid additives that to an asphalt mixture containing aged asphalt binder from sources such as Reclaimed Asphalt Pavement (RAP) or Recycled Asphalt Shingles (RAS). Aged asphalt binder generally has higher stiffness and lower durability, therefore asphalt mixtures using high amounts of RAP and/or RAS may suffer from lower performance and workability issues.

The primary function of the RA is to restore the performance properties of the asphalt mixtures. Recycling Agents such as Anova® can also significantly improve the workability and compaction of asphalt mixtures with high recycled asphalt content.

RAs may function through different mechanisms. Traditionally soft petroleum-based fluxes and oils have been used to soften the asphalt binders, countering the stiffening effect from the inclusion of the aged asphalt binder, thus acting as a “softener”. However softening does not necessarily reverse the molecular scale rigid structuring that occurs in the chemical makeup of asphalt binder as it ages, sometimes referred to as “gelling”. These gel structures are responsible for the deterioration of cracking resistance in pavements, and cannot be addressed by softening alone when higher amount of RAP or RAS are used (such as more that 25-30% by weight of the mix).

“Rejuvenators” are a special class of Recycling Agents that are chemically engineered to “compatibilize” such gel structures in the aged asphalt binder, thus restoring the durability and cracking resistance of asphalt mixture, in addition to softening.

Cargill invested heavily in product research, developing a patented proprietary chemical modification process specifically designed to modify a vegetable oil based chemistry into a “Rejuvenator” that can both soften and compatibilize aged asphalt binder, while being uniquely thermally and oxidatively stable.  

Unlike many softeners and vegetable oil additives, Cargill Anova Rejuvenator is a specialty chemical produced at Cargill industrial plants. The process follows rigorous quality control checks, and each batch is carefully tested and issued a certificate of analysis (COA). Customers receive such COAs with each batch, resulting in high product reliability and traceability. This rigorous process is another reason why Cargill Anova Rejuvenator stands out compared to competition.

Warm mix additives (WMA) are typically used for mixes with lower RAP content (often 10-20% by weight, but may vary by region and material properties), or when the mix requires improved moisture resistance. At higher RAP content a rejuvenator is the best option, providing both durability and compaction improvement.

 Due to the versatility and thermal stability of Anova Rejuvenator, it can be applied at various points in an asphalt plant:

• The most common application point for a continuous drum plant (most commonly used in North America) is inline injection into the virgin binder pipeline using an appropriate additive pump.
• For batch plants the additive may be directly applied to the RAP either before or after the RAP drier drum using a spray bar, or into the virgin bitumen balance pot, or even into the pug mill.

Cargill’s team is available to consult on the best application method for a given plant to achieve reliable and homogenous application.

Cargill’s technical team are committed to providing lab and field support to make the evaluation, design, and implementation process seamless and efficient. This starts from initial RAP and binder sampling, testing, and benchmarking, providing detailed dosing, designs, and trial plans, to plant equipment and operations consultation and support. This support does not end with the trial, but continues as a partnership as customers utilize the products, with periodic material samplings, onsite quality support, and consultation and supports on new designs and projects.

The Anova Rejuvenator rapidly penetrates and diffuses into the bitumen film at typical asphalt mix production temperatures and within the normal production and construction timeline. Therefore no additional "Dwell time" or "Storage time" needs to be applied to the treated mix prior to construction or service. Asphalt with high recycled content rejuvenated using Anova Rejuvenator can be produced and constructed similar to normal asphalt pavements with low recycled content.