rejuvenators

Rejuvenators are additives used to restore the properties of aged materials, most commonly asphalt binders in reclaimed asphalt pavement (RAP). Aging of asphalt leads to loss of maltenes, increased oxidation, and higher stiffness, which reduces ductility and low-temperature performance. Rejuvenators aim to reverse these changes by replenishing light oils and resins and by modifying the binder's chemical balance.

In asphalt technology, rejuvenators are typically oil-based formulations, including paraffinic or naphthenic mineral oils, bio-based oils (vegetable or tall oil derivatives), and resinous components. They mix with aged binder to lower stiffness, reduce viscosity at service temperatures, and improve penetration and ductility. The dosage depends on RAP content, aging level, and desired performance, and improper use can lead to accelerated aging or soft mix at high temperatures.

Applications include rejuvenating RAP for road resurfacing, recycling asphalt mixtures, and rehabilitation of aged pavements. They can be used during plant mixing or as in-place treatments. Compatibility between rejuvenator and asphalt binder is important to avoid phase separation and to ensure long-term performance.

Evaluation and performance are assessed through standard asphalt tests such as penetration, softening point, ductility, viscosity, and rheological tests, as well as aging simulations (RTFO, PAV). Monitoring for aging resistance and accelerated aging is important. Environmental and safety considerations include the use of petroleum-based solvents; growing interest in bio-based, renewable rejuvenators.

Beyond asphalt, the term rejuvenator can refer broadly to substances that restore properties of aged polymers, rubbers, or coatings by plasticization or chemical restoration, including plasticizers and conditioning oils; however, its use is most established in asphalt technology.