Sterol-Modified Asphalt Binder for Recycled Pavement Aging Control
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Solution Overview
Problem
Asphalt deteriorates with age, becoming brittle and cracking due to oxidation, especially under stress or low temperatures, making reclaimed asphalt pavement (RAP) and shingles (RAS) difficult to process and reuse effectively.
Innovation Solution
Incorporating a crude sterol additive, comprising at least 13.5 wt.% sterol molecules, into asphalt binders containing virgin asphalt, RAP, and/or RAS to retard aging and maintain or restore the original properties of the binder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reclaimed asphalt pavement (RAP) and shingles (RAS) are reused in new asphalt pavement, then material recycling and cost savings are achieved, but the aged binder becomes highly viscous and difficult to process
Solution Approach 1:
The patent changes the chemical composition parameters of the aged binder by incorporating plant-derived sterols (at least 13.5 wt.% sterol molecules) into the binder mixture. This chemical modification alters the molecular structure and reduces the viscosity of the aged binder, making it processable again while maintaining the high recycling rate of RAP and RAS materials.
2Reliability
If rejuvenators are added to recycled asphalt materials to reverse aging, then the original properties of virgin binder may be restored, but the additive requirements increase to 10% or more by weight
Solution Approach 1:
The patent employs plant-derived sterols as a cost-effective rejuvenating agent that can be used in controlled amounts (0.5 to 15 wt.% based on virgin asphalt binder) to restore the properties of aged binder. These sterols act as temporary restorative agents that improve the performance of recycled asphalt without requiring excessive quantities, unlike conventional rejuvenators.
3Stability of the object's composition
If softening agents are used to counteract aging effects in recycled asphalt, then the binder flexibility is improved, but large amounts (10% or more by weight) must be added to virgin binder
Solution Approach 1:
The patent utilizes plant-derived sterols to modify the chemical and physical parameters of the aged binder system. The sterols interact with the asphaltene-resin-maltenes structure of the binder, restoring flexibility and reducing viscosity without requiring high concentrations. This parameter change approach allows effective binder restoration at lower additive levels compared to conventional softening agents.
Data Source
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AI summary
Disclosed are binders and methods for making such binders with crude sterols. The crude sterols improve various rheological properties of the binders.