Recycled Asphalt Pavement - Purdue Engineeringncaupg/Activities/2008...Recycled Asphalt Pavement Usage PURPOSE • Increase use of RAP in Hot Mix Asphalt • Review current state of
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Recycled Asphalt Pavement
RAP Expert Task Group
January 10, 2008
Recycled Asphalt Pavement Usage
PURPOSE
• Increase use of RAP in Hot Mix Asphalt
• Review current state of the art• Identify who uses RAP • Transfer information to those who “do not”• Make recommendations for research
Recycled Asphalt Pavement Usage
Who is Using RAP?
• Survey of States and Provinces • Done by AASHTO Subcommittee on
Materials• 38 Responses (Including Ontario)
Recycled Asphalt Pavement Usage
Base– % RAP Allowed by Spec
0%10%15%20%25%≥30%n/a
Recycled Asphalt Pavement Usage
Base Mixes -- Average Use
0%1 - 10%10 - 20%20 - 30%≥30%n/a
Recycled Asphalt Pavement Usage
Intermediate - % RAP Allowed by Spec
0%10%15%20%25%≥30%n/a
Recycled Asphalt Pavement Usage
Intermediate - Average Use
0%1 - 10%10 - 20%20 - 30%≥30%n/a
Recycled Asphalt Pavement Usage
Surface - % RAP Allowed by Spec
0%10%15%20%25%≥30%n/a
Recycled Asphalt Pavement Usage
Surface Mixes -- Average Use
0%1 - 10%10 - 20%20 - 30%≥30%n/a
Recycled Asphalt Pavement Usage
Recent Experience >25% RAP
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Maximum Practical RAP Usage
Item Maximum RAP %
Base 35
Intermediate 35
Surface 35*
Considerations
•Mix Design
•Customer Specifications
•RAP Availability
•Plant Type
*Friction requirements on high-volume roads
Recycled Asphalt Pavement Usage
Ownership of RAP
ContractorAgencyBoth
Recycled Asphalt Pavement Usage
Pavement Milling
Plant Waste Material
Asphalt Pavement Removal
RAP Sources
Recycled Asphalt Pavement Usage
Recycled Asphalt Pavement Usage
Isolate RAP Sources
Blend Multiple Sources
RAP Stockpile Options
Recycled Asphalt Pavement Usage
Screening
Fractionating
Crushing
RAP Processing Options
Recycled Asphalt Pavement Usage
RAP Process Option 1
Crush to ½ in. minus
Single Stockpile
Recycled Asphalt Pavement Usage
RAP Process Option 1
Two RAP Bins (Reduce variability)
Single Size RAP minus ½ in.
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RAP Process Option 2
RAP Crushed and Screened to Two Sizes Split on ½ in.
Horizontal Impact Crusher
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RAP Size
Fine minus ½ in.
Coarse ½ to 1 in.
Recycled Asphalt Pavement Usage
RAP Process Option 2
Two RAP Bins
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Millings Only
Control RAP properties by controlling milling process
RAP Process Option 3
Recycled Asphalt Pavement Usage
RAP Gator for Lumps
One RAP Bin
RAP Process Option 3
Recycled Asphalt Pavement Usage
Top Ten Issues
• Best practices manual for – Mix design – Construction
• Performance test to evaluate RAP • Method to characterize RAP
– Avoid hazardous solvents – Gradation, Gsb, Pb, and binder grade
• Evaluate binder grade changes • Co-mingling of RAP and virgin binder unclear• Document field performance of high rap mixes • Replicate RAP and virgin plant heating in labs • Quantify RAP variability • Processing/fractionating RAP
Recycled Asphalt Pavement Usage
ETG Next Steps
• Identify Additional Information Needed• Document Success Stories• Provide Technology Transfer• Guide Document for Subcommittee on
Materials• Work with State DoTs
– Meeting March 5&6 in California
Recycled Asphalt Pavement Usage
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