Asphalt Rejuvenator Formulation for RAP Flowability
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Solution Overview
Problem
Conventional asphalt rejuvenators face challenges such as high cost, water content, and tackiness issues in hot-in-place recycling, limiting the effective reuse of reclaimed asphalt pavement (RAP) due to oxidation and brittleness, which affects the durability and lifespan of resurfaced roadways.
Innovation Solution
A novel formulation combining 50-80% bio-based asphalt rejuvenator with 20-50% virgin asphalt flux, which is flowable at room temperature, reactivates recycled asphalt binders, enhancing tackiness and flowability, reducing the need for high heat processing and equipment, and maintaining desired viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional rejuvenators are used to restore recycled asphalt properties, then the reclaimed asphalt can be reused in higher amounts, but the cost increases and water content causes tackiness issues
Solution Approach 1:
The patent changes the chemical composition parameters of the rejuvenating agent by using purified hydrocarbon distillates with specific boiling point ranges (250-450°C) instead of conventional emulsified or solvent-based rejuvenators. This parameter change eliminates water content and adjusts molecular weight distribution to achieve optimal viscosity and tackiness control while maintaining RAP compatibility
Solution Approach 2:
The patent employs readily available hydrocarbon distillates from petroleum refining processes that are typically used as fuel or solvent intermediaries. These materials are inexpensive, easily obtainable, and can be directly utilized as rejuvenators without complex processing, replacing expensive specialized rejuvenating agents
2Productivity
If high heat is applied to remove existing road surface in hot-in-place recycling, then the asphalt can be recovered, but the heat oxidizes the existing asphalt and further degrades the binders
Solution Approach 1:
The patent converts the oxidized, degraded asphalt binder that would normally be discarded into a valuable resource by using it as the base material for the rejuvenating agent itself. The oxidized asphalt is blended with hydrocarbon distillates to create a product that specifically targets and repairs oxidation damage in remaining RAP binders, turning the degradation process into a beneficial pre-treatment
Solution Approach 2:
Instead of discarding the oxidized asphalt binder removed during hot-in-place recycling, the patent recovers and repurposes it as a core component of the rejuvenating formulation. This recovered material is blended with hydrocarbon distillates to create a targeted repair agent that addresses the specific oxidation issues in the remaining reclaimed asphalt
3Reliability
If conventional rejuvenators are used to counter oxidation, then the binders are chemically revived, but the process requires high heat processing and complex equipment
Solution Approach 1:
The patent replaces complex thermal processing equipment and high-heat machinery with a chemically-based solution. The hydrocarbon distillate rejuvenator works through dissolution and chemical compatibility at ambient or moderate temperatures, eliminating the need for expensive hot-in-place recycling equipment, steam injectors, and specialized heating apparatus
4Quantity of substance
If conventional rejuvenators are used to restore asphalt properties, then the reclaimed asphalt can be reused, but energy requirements remain high
Solution Approach 1:
The patent changes the viscosity and molecular compatibility parameters of the rejuvenating agent to match the aged asphalt binder characteristics. The hydrocarbon distillates with specific boiling point ranges (250-450°C) and controlled molecular weight distributions blend efficiently with oxidized asphalt at lower temperatures, reducing the thermal energy required for mixing and application compared to conventional high-temperature processes
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This combination allows for increased use of RAP in asphalt mixtures, reducing energy requirements and extending the lifespan of resurfaced roadways by improving the flowability and performance of hot mix asphalt, while minimizing equipment needs and environmental impact.
Implementation Method 1
Rejuvenating agents help to restore a portion of the recycled asphalt properties and liquid asphalt physical properties so that the reclaimed asphalt properties more closely resemble those of virgin asphalt
Implementation Method 2
The addition of the asphalt flux provides added tackiness relative to formulations comprising rejuvenator alone
Data Source
AI summary
Roadway resurfacing often requires removal of the existing asphalt from the roadway for reuse. One method of resurfacing a roadway is hot-in-place recycling. Hot-in-place recycling employs substantial heat to remove the oxidized or aged asphalt. This heat further oxidizes the asphalt, creating a material that lacks many desirable properties (e.g., flowability) and flexibility. The disclosure provides compositions and methods that enhance oxidized asphalt, making it more viable for use in resurfacing roadways. Accordingly, compositions comprising recycled asphalt pavement and a rejuvenating agent are disclosed. The compositions combine a rejuvenator and fresh asphalt flux to make a modified asphalt rejuvenator. The modified rejuvenator is then mixed with recycled asphalt pavement to form a rejuvenated asphalt composition.