Asphalt Concrete RAP Binder Estimation Method
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The difficulty in accurately predicting the binder properties of reclaimed asphalt pavement (RAP) leads to limitations in incorporating high percentages of RAP into new asphalt concrete mixtures, resulting in unpredictable strength and wear resistance, and increased costs due to over-reliance on virgin binders.
Innovation Solution
A method involving a job mix formula (JMF) that specifies aggregate gradation and minimum effective binder content, using a iterative process to determine the working binder content of RAP, combining virgin binder and RAP with virgin aggregates, and assessing binder properties to calculate the degree of partial blending, allowing for higher RAP incorporation without compromising performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high percentages of RAP are incorporated into new asphalt concrete mixtures, then the need for virgin binders is reduced and costs are lowered, but the strength and wear resistance become unpredictable
Solution Approach 1:
The patent changes the parameter of binder content specification from total binder content to effective binder content (EBCT). This parameter change allows for accurate prediction of mixture performance by focusing on the portion of binder that actually contributes to binding, thereby resolving the unpredictability issue while enabling high RAP incorporation.
Solution Approach 2:
The patent replaces traditional trial-and-error mixing approaches with a calculated methodology based on EBCT. By substituting empirical methods with a systematic calculation approach involving binder extraction, solvent removal, and precise weighing, the patent achieves predictable results with high RAP content.
2Ease of manufacture
If traditional methods are used to determine binder content in RAP, then the process is simple, but the accuracy of predicting RAP binder properties is poor
Solution Approach 1:
The patent performs preliminary extraction of the binder fraction from RAP using a solvent before determining the effective binder content. This preliminary action separates the binder from the aggregate and other components, enabling accurate measurement of the actual binder content and its properties.
Solution Approach 2:
The patent uses a solvent as an intermediary to extract the binder fraction from RAP. The solvent acts as a mediator that selectively dissolves the binder, allowing for precise separation and measurement of the binder content without directly measuring the complex RAP mixture.
3Quantity of substance
If the binder content in RAP is overestimated, then higher RAP percentages can be used, but the structural properties of the asphalt concrete are compromised
Solution Approach 1:
The patent implements a feedback mechanism where the effective binder content is calculated and used to adjust the virgin binder addition. By measuring the actual EBCT and comparing it with the required binder content for the desired performance, the methodology provides feedback that ensures structural properties are maintained while maximizing RAP usage.
Data Source
AI summary
A method of making asphalt concrete mixtures including reclaimed asphalt pavement (RAP). Variability in the fraction of binder that occurs in RAP that is able to melt and mix with virgin binder included in the concrete mixture previously made it difficult to select an appropriate amount of virgin binder. Methods described herein permit an asphalt concrete mix designer to determine the amount of virgin binder that can be combined with RAP and virgin aggregate in order to satisfy the minimum effective binder content of a job mix formula for such a concrete mix. The subject matter described herein thus permits more efficient use of RAP and permits use of RAP in higher amounts in asphalt concrete mixtures.