Shingle Recycling

Colorado Department of Transportation releases draft RAS specification

By Dan Krivit

There has been a lot of recent activity in Colorado on shingles recycling. The Colorado Department of Transportation (CDOT) recently released a draft materials specification for the use of recycled asphalt shingles (RAS) in hot mix asphalt (HMA). CDOT is planning on conducting several research demonstration projects including the first one this season on State Highway 36 near Broomfield, northwest of Denver. The demonstration project includes side-by-side tests within a 4 mile mill-and-fill project. The east bound lanes are using a traditional asphalt mix without RAS and the west bound lanes are using 3% RAS from shingle manufacturers.

Other recent activity includes the April 26 Colorado Reclaimed Asphalt Shingle Workshop co-sponsored by CDOT. Held in CDOT’s headquarters in Denver, the workshop covered some of the results to date on other demonstrations completed as part of the Federal Pooled Fund Study. This Pooled Fund Study  is under the administrative lead of Missouri DOT and research lead of Iowa State University.1 CDOT is one of the state partners on the Pooled Fund Study and the demonstration paving project on U.S. Hwy. 36 will become part of the research analysis of similar national field and lab tests.

The draft CDOT specification is known as a “project special provision” and allows for a maximum of 5% RAS in HMA as long as all other asphalt paving specifications are met. The draft references the American Association of State Highway Transportation Officials (AASHTO) materials provisional (MP) specification.2 For example, similar to the AASHTO specification, CDOT limits the maximum amount of all deleterious materials to 3% by total mass in the RAS and 1.5% by mass for lightweight materials (such as paper, wood and plastic). In addition, the CDOT specification requires the RAS moisture content shall not exceed 15% by mass.

CDOT limits the amount of recycled binder (asphalt cement or oil) to a maximum of 30% by stating the mix must have a minimum of 70% effective virgin (or new) binder. RAS may be used together with reclaimed asphalt pavement (RAP), but the combined total effective recycled binder from RAS binder plus RAP binder shall not exceed 30%. In the CDOT Hwy 36 demonstration, the RAS test mix included 3% RAS plus 15% RAP. The traditional mix included 20% RAP. The total amount of HMA on this project is about 22,000 tons, half with the RAS mix and half with the traditional mix. 

Asphalt Specialties Co., Inc. (ASCI) based in Henderson, Colo., was the successful contractor for the CDOT Hwy 36 project. ASCI has been developing its ability to use both tear-off and manufacturers’ shingles to produce a quality RAS product that meets the new CDOT specification. ASCI elected to use manufacturers’ RAS on the Hwy 36 demonstration even though the CDOT specification allows for both types including tear-offs.

The CDOT specification requires the contractor to provide asbestos test results certifying compliance with the U.S. Environmental Protection Agency’s (EPA) National Emission Standards for Hazardous Air Pollutants (NESHAP). ASCI completed all of its required engineering and environmental tests on the RAS being used in the Hwy 36 project. According to Gary DeWitt, CDOT’s Region 4 materials engineer, no asbestos was detected in any of the samples. 

At the recent RAS Workshop, representatives of the Colorado Department of Public Health and Environment (CDPHE), U.S. Environmental Protection Agency (EPA) and U.S. Occupational Safety and Health Administration (OSHA) were part of an afternoon panel of environmental regulatory officials. The CDOT materials specification is explicit in requiring asbestos content sampling of the finished RAS (after the grind) at a once every 1,000 tons with a minimum of three tests. Other provisions in the draft CDOT specification address:
•    Quality control plan requirements;  
•    Representative sampling so that the samples reasonably represent the final RAS product used in the HMA;  
•    RAS gradation (100% passing the 3/8-inch sieve and a minimum of 90% passing the number 4 sieve);  
•    Allowing pre-blending of RAA with sand or fine aggregate to assure the mixture is workable; and
•    Other specific materials sampling and testing standards and methods are specified.

It is interesting to note there are several independent shingle recyclers in Colorado, including Asphalt Recovery Specialists, Inc. (ARS) in Colorado Springs as featured in the May/June 2011 issue of C&D World. In addition, there are multiple options for shingle recycling in the Denver and Boulder Colorado region, including HMA companies like ASCI that have vertically integrated into to produce their own RAS for their internal use.

One of the other significant influences helping promote shingle recycling in Colorado is the non-profit organization Roofs to Roads Colorado. The Roofs to Roads Project was launched in February 2009, after two years of planning and initial work. Roofs to Roads is working in the public interest with support from the CDPHE, Pollution Prevention Advisory Board, Advanced Technology Grant, from Boulder County Resource Conserva-tion Division’s Community Outreach Program, and from Region 8 of the EPA.3

Another development in Colorado is the research project being conducted by Colorado State University by Scott Shuler, Associate Professor. His project is looking at the “Use of Asphalt Shingles from Tear-Offs in HMA.”

With the help of many partnering agencies, researchers, shingle recycling entrepreneurs, and HMA contractors, the future of shingle recycling in Colorado is looking very positive. The recent CDOT specification, current and planned paving demonstrations, and collaboration among the many players in this growing industry spell out prospects for continued growth and improvement.

About the Author
Dan Krivit is a senior project manager with Foth Infrastructure & Environment, LLC and can be reached at 651-288-8509; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Endnotes
¹ The transportation pooled fund (TPF) study, Performance of Recycled Asphalt Shingles in Hot Mix Asphalt, TPF-5(213), was organized in late 2009.  The goal of the research, co-sponsored by the Federal Highway Administration (FHWA) and lead by Missouri Department of Transporta-tion (MoDOT), is to examine any specific behavior and performance differences of tear-off shingles in HMA.  Current state partners include: CA, CO, FHWA, IA, IL (Illinois Tollway), IN, MN, MO and WI. The principal technical researcher is Chris Williams, Associate Professor at Iowa State University, Depart-ment of Civil, Construction and Environmental Engineering.  A second researcher is Mihai Marasteanu, Assistant Professor at the University of Minnesota, Department of Civil Engineering.  For more details
on the project outline, go to: http://www.pooled-fund.org/projectdetails.asp?id=441&status=4

² AASHTO MP015-09-UL: Standard Specification for Use of Reclaimed Asphalt Shingles as an Additive
in Hot Mix Asphalt (HMA). (For ordering information, link to: https://bookstore.transportation.org/item_details.aspx?ID=1420 .)
AASHTO PP053-09-UL: Standard Practice for Design Considerations When Using Reclaimed Asphalt Shingles (RAS) in New Hot Mix Asphalt (HMA). (For ordering information, link to: https://book-store.transportation.org/item_details.aspx?ID=1421 .)

³ For more information about
Roofs To Roads Colorado, see: http://www.roofs2roadscolorado.org/aboutus.php

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