Session #3 Asphalt 103- Materials: Basics of RAP, Usage and Specifications

Colorado DOT RAP Specifications Roy Guevara CDOT Asphalt Pavement Program Rocky Mountain Asphalt Conference February 2009

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.  Environmentally friendly

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 Standard Special Revision of Section 401

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. Standard Special Revision of Section 401

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 Standard Special Revision of Section 401

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. Standard Special Revision of Section 401

Bumping Grade Example Plans require a PG If >20% RAP is used, the binder is bumped down to a PG 58-28

CDOT Binder Grades CDOT GradeBumped Down Available? PG PG 70-34No PG PG 58-34Yes PG PG 58-28Yes PG PG 52-40No PG PG 52-34No

Tiered approach <20%No binder changes 20% - 25% Grade bump down both high and low end >25%Use blending charts

CDOT RAP Specification Highlights Section “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”

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

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 (b): one strike you’re out language was deleted. RAP allowed on Gradation Acceptance projects at Region Materials Engineer’s discretion

RAP Task Force Changes New procedure outlining process for mix designs that use millings from same project (CPL 5145) RAP Sampling Sample preparation Test Samples RAP Processing Testing

CDOT RAP Usage Statistics RAP is usually allowed on most voids acceptance and non SMA projects No explanation for drop in use in was first season that did not require virgin mix design and “1 strike you’re out” language was deleted.

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

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

2008 Ontario Ministry Survey 7 agencies do not permit RAP use on top lifts of heavily traffic areas (>30 million 20 year design ESALs) Bad experience Lack of experience/ confidence with RAP in the wearing course 2 agencies do not permit it at any layers for heavy traffic areas

CDOT RAP Uses In asphalt mixes Hot and Cold Recycling Shouldering As a base CDOT Maintenance yard parking lots

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