Is your lab staff tasked with adding a recycling agent to your high-RAP mix? Someone may have sold the additive to you as a rejuvenator, and that’s fine. The phrase “rejuvenating agent” is used more commonly, but this family of products includes both rejuvenators and softeners. You’ll want to know which one you’re working with in the lab.
Keep in mind, softening agents are low viscosity products that are designed to reduce the stiffness of the binder. Rejuvenators also reduce the binder’s stiffness, but they can also help restore the chemical balance of the binder blend; rejuvenators can also reduce brittleness as they are designed to “rejuvenate” the oxidized liquid asphalt cement (AC) within the reclaimed asphalt pavement in your mix.
When the lab gets to work, remember that recycling agent doses are usually provided by weight of total binder (that’s the virgin plus recycled). You’re typically replacing the virgin binder (or a portion of it) with the recycling agent. The goal is to reduce the amount of virgin binder by the amount of recycling agent you’re adding so the total binder content remains constant. Your best bet is to follow the additive supplier’s recommendations for dosing. This dosing rate affects the preparation of binder blend and the development of the mix during design. The dosing rate also needs to be communicated clearly to the plant operator so control settings are right during production.
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