How Molecular Rejuvenation Restores Aged Bitumen

Porousan

July 20, 2025

Rejuvenation is not simply 'softening'; it is a chain of controllable chemical and physical processes. Understanding the mechanism is the key to using high RAP content well.

Oxidation and hardening

In aged bitumen, light fractions escape and resins convert to asphaltenes; molecular cross-links intensify, showing as harder, more brittle material with poor low-temperature cracking resistance.

Molecular de-crystallization

Targeted components cleave and depolymerize the brittle oxidized fragments, restoring molecular mobility and flexibility so the rejuvenated asphalt regains good workability.

Steric-hindrance resin and re-crystallization

The steric-hindrance resin forms a spatial barrier around molecules, suppressing re-crystallization and aggregation so the asphalt stays stable in storage and service.

3-D cross-linked network

A latent reactive component gradually activates at medium mixing temperature, building a three-dimensional cross-linked structure that strengthens the mix and its fatigue resistance.