Reclaimed asphalt pavement (RAP) may offer significant cost and other benefits. However, RAP usage has plateaued because of concerns about premature pavement failures linked to stiff recycled binders. Recycling agents (RAs) can improve the activation and performance of aged binders, but their effectiveness depends heavily on how they are introduced—either pre-blended with virgin binder or directly applied to RAP (pretreatment). While laboratory evaluations suggest potential benefits, the real-world impact of these methods remains unclear, limiting RA adoption and RAP utilization.

There is a need to assess how RA introduction methods affect high RAP mixtures under actual plant production and field conditions, accounting for variables such as binder diffusion, RAP conditioning time, and plant process parameters.

The objective of this research is to evaluate and compare the effectiveness of RA pre-blending and pretreatment methods for high RAP mixtures in plant production settings, using laboratory and field performance data to inform practical implementation strategies.

Potential research tasks include:
• Conduct an inventory of RA incorporation practices and identify key production parameters for evaluation.
• Define protocols for RA selection, dosage optimization, and monitoring of plant-produced mixtures.
• Execute field trials comparing pre-blending and pretreatment methods, including variations in RAP conditioning.
• Place test sections using different RA methods and monitor field performance over 2.5 years.
• Analyze the impact of RA methods on mixture durability (e.g., aging, cracking, raveling) using Balanced Mix Design principles.
• Provide recommendations for RA incorporation practices and update relevant design and production guidelines.