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1. Session #3 Asphalt 103- Materials: Basics of RAP, Usage and Specifications
2. Colorado DOT RAP Specifications Roy Guevara
CDOT Asphalt Pavement Program
Rocky Mountain Asphalt Conference
3. Reasons For Using RAP Energy and Cost Savings
1 ton of RAP conserves 200,000 BTU’s of Energy
Aggregate mining, processing & delivery
Asphalt refining & delivery
Conserve our valuable natural resources.
4. CDOT RAP Specifications Highlights Use on projects with voids acceptance of hot mix asphalts
May be used on other projects as determined by the Region Materials Engineer
5. CDOT RAP Specifications Highlights 20% RAP allowed on top lifts
25% RAP allowed in all other lifts
Contractor may use more RAP if they follow AASHTO MP-1 specifications
Contractor must have an approved mix design for the amount of RAP to be used.
6. CDOT RAP Specifications Highlights Additional Conditions:
1. Approved Quality Control Plan detailing how RAP will be processed and controlled.
RAP Processing Techniques
Control of RAP Asphalt Binder Content
Gradation testing 1/1000 tons of HMA
7. CDOT RAP Specifications Highlights 2. Processed RAP must be 100% passing the 1 ¼” sieve (31.5mm)
3. If RAP content is >20%, binder is bumped down one grade on both the high and low ends.
8. Bumping Grade Example Plans require a PG 64-22.
If >20% RAP is used, the binder is bumped down to a PG 58-28
9. CDOT Binder Grades CDOT Grade Bumped Down Available?
PG 76-28 PG 70-34 No
PG 64-28 PG 58-34 Yes
PG 64-22 PG 58-28 Yes
PG 58-34 PG 52-40 No
PG 58-28 PG 52-34 No
10. Tiered approach <20% No binder changes
20% - 25% Grade bump down both high and low end
>25% Use blending charts
11. CDOT RAP Specification Highlights Section 401.22
“When asphalt cement is a separate pay item, the amount of asphalt cement contained in RAP material will NOT be measured or paid for but shall be included in the work”
12. Project Special Provision 202
RAP Value Engineering Cost Proposal
Indicate the amount of RAP millings CDOT will retain
If Contractors desire to retain all or more than what is allowed in the contract, Contractor can submit VECP CDOT RAP Specification Highlights
13. RAP Task Force Changes Increased RAP usage from 15% to 20% allowed in top layers
RAP mixes treated like virgin mixes
-2 mix designs no longer required
-subsection 401.02(b): one strike you’re
out language was deleted.
RAP allowed on Gradation Acceptance projects at Region Materials Engineer’s discretion
14. RAP Task Force Changes New procedure outlining process for mix designs that use millings from same project (CPL 5145)
RAP Processing Testing
15. CDOT RAP Usage Statistics
16. CDOT RAP Survey Findings
Survey found that there were only minor obstacles for allowing or using RAP
For CDOT, testing manpower and high profile projects were barriers for allowing RAP
For Contractors, remote areas with no RAP piles and lack of equipment were barriers
17. 2008 Ontario Ministry Survey 15% to 20% RAP allowed on top lifts
20% to 40% RAP allowed for other lifts
Contractors tend to use only 20% to 25% even when higher levels are allowed
18. 2008 Ontario Ministry Survey 7 agencies do not permit RAP use on top lifts of heavily traffic areas
(>30 million 20 year design ESALs)
Lack of experience/ confidence with RAP in the wearing course
2 agencies do not permit it at any layers for heavy traffic areas
19. CDOT RAP Uses In asphalt mixes
Hot and Cold Recycling
As a base
CDOT Maintenance yard parking lots
20. Thank you