C & D Recycling Program
Asphalt Roofing Shingles in
Introduction increased stability, decrease in temperature
susceptibility, improved compaction, and improved
This fact sheet is an overview of the use of ground "rideability" index.
asphalt roofing shingles in asphalt pavement,
including potential markets and discussion on Processing
Hot-mix asphalt (HMA) is the most common
For general information on asphalt shingles process to which shingles can be added. Waste
recycling, including composition, processing, siting, shingles are ground and screened to produce 1/2"-
equipment, and other possible products, order the minus-size pieces for batch plants, or 1/4"-minus-
CIWMB fact sheet Asphalt Roofing Shingles size pieces for continuous feed plants. The ground
Recycling: Introduction shingles are usually fed into and mixed with the
(Pub. #431-97-031). Ordering information for aggregate before adding the virgin asphalt binder.
CIWMB publications is on page 3.
A number of laboratory and field projects in North
A roadway is built in several layers: pavement, America have tested shingles in AC. Some of
base, and sometimes subbase. The pavement is these projects have led to specifications from state
the surface layer. Asphalt pavement is usually departments of transportation (DOT).
referred to as asphalt concrete, or AC. The base
is made of a layer of aggregate base over a layer DOT Specifications
of aggregate subbase. State DOTs that allow asphalt roofing shingles in
asphalt pavement include:
Benefits • Georgia (5 percent, manufacturing scrap only).
In addition to saving landfill space, the benefits to • Maryland (5 percent, manufacturing scrap only).
recycling asphalt shingles in AC include possible
economic savings and improved pavement • Michigan (50 percent recycled asphalt spec
performance. routinely allows old and new shingles, though
shingles are not specifically mentioned).
There may be an immediate economic benefit due • Minnesota (5 percent, manufacturing scrap
to asphalt reclamation. California plants produce only).
fiberglass-based shingles, which are approximately • New Jersey (5 percent in "supplemental" spec,
20 percent asphalt. AC is approximately 6 percent manufacturing scrap only).
asphalt. So a small percentage of shingles (e.g., 5
percent by weight of aggregate) can displace a • North Carolina (5 percent, manufacturing scrap
large percentage of asphalt binder (approximately only).
20 percent). Other economic factors include • Ohio (allows "certain percentage of recycled
recyclers' tipping fees, costs to grind the shingles, material").
price of virgin asphalt, and transportation costs.
• Indiana DOT (5 percent, manufacturing scrap
Pavement Performance only).
Another benefit may be improved pavement
performance. Because the asphalt used in shingles • Florida DOT began a test project to develop
is harder than pavement asphalt, the pavement specifications. It was not finished, for reasons
benefits may include improved resistance to rutting,
C & D Recycling Program
unrelated to technology. According to Mr. Gayle Paige of the State Materials Office,
research indicates that shingles can comprise Greenbook Procedures
5 percent of pavement, and even 15 percent if If the Greenbook were to include specifications for
engineered properly. shingles in AC, the process may include the
The City of Brampton, Ontario allows 3 percent new 1. A local government tests the method in the
and old asphalt roofing shingles in AC. field.
2. The local government submits test results to
the Greenbook Committee.
The key to opening large California markets for
3. The Greenbook Committee assigns it to a
asphalt shingles in asphalt pavement is to allow the
specialized Greenbook committee, perhaps the
shingles in California’s construction specifications.
Surface Committee, which looks at test results,
The specifications most widely used in California
and recommends approval or rejection of the
are Caltrans specifications and the Greenbook.
4. The Greenbook Committee votes to approve or
Caltrans specifications are used by Caltrans
reject the specification.
projects, most local government public works
departments in Northern California, and many
CIWMB Proposal to Caltrans
private projects. Caltrans testing of new road
products adds a high level of confidence to a Proposal
product or method. Caltrans specifications for In January 1997, CIWMB submitted a proposal to
shingle-content AC would significantly improve Caltrans’ Pavement Design and Rehabilitation
marketing prospects for recycled shingles. Committee (PDRC). The proposal suggested that
Caltrans specifications currently do not allow Caltrans (1) write an SSP allowing 5 percent ground
asphalt shingles in AC. factory scrap asphalt shingles in hot mix asphalt
pavement, and (2) conduct any tests needed to
accomplish this. The proposal included a draft
If Caltrans were to write specifications for shingles
specification modeled after existing DOT
in AC, the process might include the following
specifications from other states.
1. Test in the laboratory.
In February 1997, CIWMB submitted to Caltrans a
2. Write draft specifications, which are called cost/benefit analysis investigating the use of ground
Special Provisions (SP). shingles in AB and in AC. The analysis was
favorable for AC.
3. Test in the field, perhaps on a heavily trafficked
road such as a truck weigh station. Response
Caltrans responded to the proposal in a letter dated
4. Monitor for several years.
May 5, 1997, which indicated that Caltrans is not
5. Write specifications called Standard Special interested in evaluating shingles in AC at this time.
Provisions (SSP). These SSPs would then be
available for routine use in Caltrans and local Local Government Testing
The most promising market at this time may be
Greenbook Specifications local government public works. Although local
The Greenbook is officially titled Standard governments usually use Caltrans or Greenbook
Specifications for Public Works Construction. specifications, they are free to use any specifica-
It is used by the City and County of Los Angeles tions of their choosing, or develop their own, for
and 200 other local governments and agencies in projects using local funds. Local governments
the Los Angeles area. Greenbook specifications could start with existing specifications from other
currently do not allow asphalt shingles in AC. state departments of transportation, and adapt them
to local needs; test projects could begin with
parking lots and low impact roads. Areas near
shingle manufacturing plants may be particularly Alameda County Project
interested, such as the counties of Los Angeles, Alameda County Waste Management Authority
Orange, Contra Costa, San Bernardino, and Kern. gave Raisch Products a grant to research and
develop (1) processing equipment to grind
shingles, and (2) markets, including but not limited Reports
to AC. Findings will be made public through Evaluation of the Benefits of Adding Waste
Alameda County and are expected in 1998. Fiberglass Roofing Shingles to Hot-Mix Asphalt,
July 1997, Ohio DOT, Office of Materials
Private Markets and Testing Management, by CTL Engineering, Columbus,
Private markets include private roads, parking lots,
driveways, and farm roads. Although many private Minnesota’s Experience Using Shingle Scrap in
owners also depend on Caltrans, Greenbook , or Bituminous Pavements, October 1996, Minn. DOT,
local public works specifications, some may be David Janisch of Office of Minnesota Road
willing to accept shingles in asphalt, especially if Research and Curt Turgeon, Metropolitan Division.
the asphalt is tested for certain quality standards.
Influence of Roofing Shingles on Asphalt Concrete
There are approximately eight private laboratories in
Mixture Properties, June 1993, University of
California that test asphalt products.
Minnesota, Dept. of Civil and Mineral Engineering.
Publications Mechanistic Evaluation of Asphalt Concrete
Mixtures Containing Reclaimed Roofing Materials,
Free CIWMB Publications
N. Ali, Dept. of Civil Engineering, Technical
CIWMB has published a series of fact sheets, case
University of Nova Scotia, Canada, Transportation
studies, and resource lists on construction and
Research Record 1515.
demolition recycling. CIWMB publications can be
obtained in two ways: Evaluation of the Benefits of Adding Waste Asphalt
Roofing Shingles to Hot Mix Asphalt, Ohio State
Internet. Visit the Board’s C&D Web site at
University, Transportation Technology Transfer
www.ciwmb.ca.gov/ConDemo/. You can view, print,
Center, Department of Civil Engineering, sponsored
or download most publications, and search the
by Ohio Department of Transportation and Federal
Mail. To order through the mail, call the CIWMB
Recovery and Reuse of Asphalt Roofing Waste -
Publications Clearinghouse at (800) CA-WASTE, or
Incorporation of Roofing Waste in Asphalt Paving,
(916) 341-6308 from outside California. To find out
Vol. I (Lab Investigation) & Vol. II (Analysis), Sept.
what is available, request the four-page summary of
1986, University of Nevada, Reno, Nevada and
the C&D program and publications, Construction &
Manville Sales Corp., Denver, Colorado for U.S.
Demolition Recycling Program (Pub. #431-97-030).
Department of Energy.
Recommended CIWMB Publications
The following publications are recommended: CIWMB Contact
Asphalt Roofing Shingles Recycling: Introduction. For more information about recycled shingles in
A three-page overview of shingles recycling, asphalt pavement, or to obtain documents
intended to accompany this fact sheet. mentioned in this fact sheet, contact Sabra
(Pub. #431-97-031) Ambrose at (916) 341-6499 or by e-mail at
Asphalt Pavement Recycling. A four-page overview
of recycling asphalt pavement back into asphalt
pavement, including recycling methods, Greenbook
and Caltrans specifications, organizations, and
siting considerations in California. (Pub. #431-95-