Refined Separation Treatment for Reclaimed Asphalt Pavement (RAP) Processing: A Review

Area of Science:

• Civil Engineering
• Materials Science
• Environmental Engineering

Background:

• Reclaimed asphalt pavement (RAP) offers significant economic and environmental advantages in road construction.
• Inconsistent RAP quality, due to material complexity and poor management, limits its efficient application.
• Particle agglomeration, where aged asphalt mortar binds aggregates, is a primary cause of RAP variability, affecting gradation measurements and binder contribution.

Purpose of the Study:

• To critically review refined RAP separation treatments for reducing variability and enhancing performance consistency.
• To evaluate rotary centrifugal decomposition as a supplementary RAP processing technique.
• To identify challenges and areas for future research in RAP processing.

Main Methods:

• Critical review of recently developed RAP separation treatments.
• Focus on rotary centrifugal decomposition for disaggregating RAP agglomerates.
• Analysis of large-scale application data for separation efficiency and fraction characteristics.

Main Results:

• Rotary centrifugal decomposition effectively disaggregates RAP agglomerates, recovering coarse aggregates with minimal aged asphalt.
• This method efficiently produces well-graded RAP fractions, separating recycled coarse aggregates (5-20 mm) from bitumen-rich fine RAP (0-5 mm).
• Demonstrated potential to improve RAP recycling rates and the performance of high-RAP-content mixes.

Conclusions:

• Rotary centrifugal decomposition is a promising technique for improving RAP quality and enhancing recycled asphalt mix performance.
• Challenges include preserving coarse aggregate integrity, controlling gradation refinement, and managing fine RAP fractions.
• Further research is essential to optimize the separation process, minimize material degradation, and assess long-term cost-effectiveness.