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Environmental and Health Issues and Recommendations  Recycled Content:
The use of recycled aggregate, rather than virgin aggregate, will help to conserve finite natural resources and help keep waste asphalt, concrete, and other inerts out of landfills.   
Air Quality, Energy Conservation, Global Warming:
If recycled aggregate is produced on-site or obtained from sources that are closer to the project site than virgin aggregate quarries, this can reduce the environmental impacts associated with using fossil fuel in transport trucks. Reducing the use of fossil fuel reduces air pollution, conserves energy, and reduces greenhouse gas emissions.
See the Introduction for complete descriptions of these environmental and health issues.
BACKGROUND AND ENVIRONMENTAL AND HEALTH ISSUES
Aggregate consists of hard, graduated fragments of inert mineral materials, including sand, gravel, crushed stone, slag, rock dust, or powder. Recycled aggregate is produced by crushing concrete, and sometimes asphalt, to reclaim the aggregate according to strict manufacturing standards. In 2004, California imported more than two million tons of virgin construction sand and gravel, [1] and disposed of 977,000 tons of aggregate rich asphalt and concrete. [2] Recycled aggregate can be used for many purposes. The primary markets are for road base and subbase.
The use of recycled aggregate can save money for local governments and other purchasers, create additional business opportunities, save energy when recycling is done on-site, conserve diminishing resources of virgin aggregates, and help local governments meet the diversion goals of the California Integrated Waste Management Act of 1989.
A roadway is built in several layers: pavement, base, and sometimes sub-base. The pavement is the surface layer, and is made of portland cement concrete (PCC) or asphalt concrete (AC). The base layer supports the pavement, and is made of aggregate base (AB). The subbase layer supports the base and is made of aggregate subbase (ASB). The subbase layer allows more sand, silt and clay than the AB layer; the subbase layer has less strength, but is used because it is more economical when bringing the road up to grade (finished height).
Along with AB and ASB, recycled aggregate can also be used for engineered fill, fill for utility trenches, or other construction base material. Always make sure the material used meets the specifications for the project.
Environmental and Health Issues
Recycled Content Inert solid waste is concrete, asphalt, dirt, brick, and other rubble.
PCC and AC consist primarily of aggregate and either cement or asphalt as a binder. Some PCC contains steel reinforcement bars, or "rebar," such as a bridge deck or tilt-up slabs. When a road or structure is demolished, the rebar can often be seen protruding from the broken chunks of PCC.
Recycled aggregate comes primarily from PCC and AC from road demolition, rehabilitation, and maintenance; building demolition; and leftover batches of AC and PCC. AC or PCC feedstock waste can either be hauled to a construction and demolition waste processor or can be processed on-site. Strict quality control standards are implemented by processors to ensure that deleterious materials such as wood, plastic, metals and other contaminants are not commingled with the waste AC or PCC. Waste concrete or asphalt is then processed by running the material through a series of crushers and screens to a specified size or gradation. Quality feedstock, material with little deleterious material, will make a higher quality end product. It can either be stockpiled at a facility or processed on-site for use in the project.
Air Quality, Energy Conservation, Global Warming
Depending on certain factors, air pollution may be reduced with the use of recycled aggregate. Many quarries are located in outlying areas, away from project sites; while recycling facilities are often located in or near many communities where road construction occurs. Trucks transporting aggregate to the job-site are sources of both greenhouse gases and particulate matter. Reducing the number of trip miles by using locally produced recycled aggregate will help reduce those types of pollution, and save energy in the form of fossil fuel used to power transport trucks. On-site processing may eliminate those trip miles completely.
Finally, crushing of concrete creates dust; therefore, proper controls should be in place.
LAWS AND GUIDELINES
California
Statute
California Integrated Waste Management Act (IWMA) of 1989 (Assembly Bill 939, Sher, Chapter 1095, Statutes of 1989)
Among other things, the IWMA required each city or county to divert 50 percent of solid waste from landfills and transformation facilities by 2000 through source reduction, recycling, and composting activities. The use of recycled aggregate can save money for local governments and other purchasers, create additional business opportunities, save energy when recycling is done on-site, conserve diminishing resources of urban aggregates, and help local governments meet the diversion goals of the IWMA.
Chapter 392, Statutes of 2006 (Simitian, Senate Bill 420)
This bill amended Section 42701 of the Public Resources Code to read:
42701. (a) In purchasing any materials to be used in paving or paving subbase for use by the Department of Transportation and any other state agencies that provide construction and repair services, the State Procurement Officer shall contract for those items that utilize recycled materials in paving materials and base, subbase, and pervious backfill materials, unless the Director of Transportation determines that the use of the materials is not cost effective. In determining the cost-effectiveness of the materials subject to this section, the factors that the director shall consider include both of the following: (1) The lifespan and durability of the pavement containing the materials. (2) The maintenance cost of the pavement containing the materials. (b) This section also applies to any person who contracts with the Department of General Services or with any other state agency to provide these construction and repair services. (c) The recycled materials shall include, but are not limited to, recycled asphalt, crushed concrete subbase, foundry slag, and paving materials utilizing crumb rubber from automobile tires, ash, and glass and glassy aggregates. The specifications shall be based on the standards of the Department of Transportation for recycled paving materials and for recycled base, subbase, and pervious backfill materials.
State and Local Permitting Issues
On-site processing may require certain State and local permits, such as air, water, and zoning.
- Air Permits: The local air districts may be concerned about nuisance odors and may require processors to spray materials with water to control dust.
- Water Permits: The Regional Water Quality Control Board may require a permit for the facility depending on feedstock and location.
- Solid Waste Permits: Regulations affecting construction and demolition (C&D) and inert debris transfer/processing generally exempt on-site processing from Solid Waste permit requirements. Contact your Local Enforcement Agency (LEA) for more information.
Federal
The Federal Highway Administration's (FHWA) Recycled Materials Policy is:
- Recycling and reuse can offer engineering, economic and environmental benefits.
- Recycled materials should get first consideration in materials selection.
- Determination of the use of recycled materials should include an initial review of engineering and environmental suitability.
- An assessment of economic benefits should follow in the selection process.
- Restrictions that prohibit the use of recycled materials without technical basis should be removed from specifications.
PERFORMANCE
As long as the recycled aggregate meets the project specification, it will perform the same as virgin material.
AVAILABILITY
According to the California Integrated Waste Management Board's (CIWMB) 2004 Statewide Waste Characterization Study:
- Construction and Demolition (C&D): C&D materials made up about 22 percent of California's disposed waste stream, or approximately 8.7 million tons.
- Asphalt and Concrete: Asphalt and concrete represent more than 977,000 tons of disposal or about 2.4 percent.
According to the CIWMB's current information, there are approximately 100 producers of recycled aggregate in California. [3] Some receive PCC and/or AC at the plant; others have mobile equipment for in-place recycling. Aggregate recyclers are included in two databases: Construction and Demolition Debris Recyclers--Processors & Receivers and Recycled-Content Construction Products.
COST
Because of the weight of aggregate, transportation plays a large role in its cost. As transportation costs continue to rise, locally produced recycled aggregate will often be considerably less expensive than virgin material that needs to be brought in from an outlying quarry. Depending upon the location of the project and its proximity to a recycler, recycled aggregate can be cost neutral, or cost less per ton than virgin aggregate. The amount of money saved for a project can range from $3 to $10 a ton. [4]
On-site processing
When performing a road rehab or rebuild or a building demolition, processing on site may offer the greatest cost savings. On-site processing of project waste materials should:
- Reduce costs associated with disposal and hauling since the re-used material will not leave the site, and
- Reduce or eliminate the costs to purchase and haul aggregate to the job-site.
SPECIFICATIONS
California
California Department of Transportation (Caltrans) Specifications
Many local jurisdictions use Caltrans specifications. In Southern California, the Greenbook is commonly used (see Greenbook discussion below). Where recycled aggregate is allowed, it must also, of course, meet the same grading and quality specifications as virgin aggregate.
Caltrans Specifications-Procedures: Caltrans takes a new specification through three stages:
- Special Provision (SP). First it is an SP where it is used initially on a number of projects.
- Standard Special Provision (SSP). After the SP has been used successfully for a period of time, it usually becomes an SSP which means that it is a method approved by Caltrans.
- Standard Specification. After the SSP has been used successfully for a period of time, then it usually becomes a Standard Specification, and is included in Caltrans Standard Specifications which are published every four years.
Caltrans Specifications-Existing: Caltrans' May 2006 Standard Specifications cover aggregate base and aggregate subbase in Sections 25 and 26. These sections allow up to 50 percent recycled aggregate. Caltrans' SSPs allow up to 100 percent "reclaimed asphalt concrete, portland cement concrete, lean concrete base, cement treated base," or "glass" in Class 2 and 3 aggregate base, and also in Class 1, 2, and 3 aggregate subbases.
Greenbook Specifications
The Greenbook, or Standard Specifications for Public Works Construction, is used by the City and County of Los Angeles and 200 other local governments and agencies in the Los Angeles area. It is updated and published every three years by the Joint Cooperative Committee of the Southern California Chapter of the American Public Works Association, and the Southern California Districts of the Associated General Contractors of California. Supplements are published yearly. The Greenbook includes both English and metric units, and is available through BNi Building News.
Aggregate Base Specifications
In Section 200-2, "Untreated Base Materials," the Greenbook includes four categories of aggregate base that are of interest here:
- Crushed Aggregate Base (CAB) does NOT include recycled aggregate. CAB may sometimes be specified where recycled base (crushed miscellaneous base or processed miscellaneous base) would also meet requirements.
- Crushed Miscellaneous Base (CMB) allows recycled aggregate. The Greenbook states that CMB "shall consist of broken and crushed AC or PCC and may contain crushed aggregate base or other rock."
- Processed Miscellaneous Base (PMB) also allows recycled aggregate. The Greenbook states that PMB "shall consist of broken or crushed AC, PCC, railroad ballast, glass, crushed rock, rock dust, or natural material."
- Select Subbase is the Greenbook's only aggregate subbase category. It allows recycled aggregate.
Section 200-2.4 spells out the performance standards for CMB.
American Association of State Highway and Transportation Officials (AASHTO)
Standard Specification for Reclaimed Concrete Aggregate for Unbound Soil-Aggregate Base Course, AASHTO Designation: M 319-02 (PDF, 156 KB).
VENDORS
According to the CIWMB's current information, there are approximately 100 producers of recycled aggregate in California. [5] Some receive PCC and/or AC at the plant; others have mobile equipment for in-place recycling. Aggregate recyclers are included in two CIWMB databases: Construction and Demolition Debris Recyclers--Processors & Receivers and Recycled-Content Construction Products.
SUCCESS STORIES
California
California Department of Transportation (Caltrans)
Recycled aggregate has been successfully used by Caltrans as road base and subbase since the 1970s.
San Mateo County
"In 2005, San Mateo County adopted a policy specifying that recycled aggregate be the preferred material for all non-structural concrete applications, including but not limited to sidewalks, base material, and sub base material. Suppliers have been able to provide the material needed at the same or lower cost, and results have been favorable. Not only has the county been able to implement this policy without added cost to the taxpayers, it supports the County's long term goal to reduce the amount of material that needs to be landfilled." [6]
Minnesota
See the Road Aggregate section of the Environmentally Preferable Purchasing Guide, published by the Solid Waste Management Coordinating Board of Minnesota.
RESOURCES AND WEBSITES
Alberta, Canada, Government of
Construction, Renovation & Demolition Waste Reduction
See the following report: Market Development Study for Recycled Aggregate Products. Report to Waste Reduction Advisory Committee, Alberta, Canada (PDF, 34 pages, size unknown).
American Public Works Association
Kansas City, MO
(816) 472-6100
The American Public Works Association is an international educational and professional association of public agencies, private sector companies, and individuals dedicated to providing high quality public works goods and services.
California Department of Conservation
Division of Mines and Geology (aka California Geological Survey)
Sacramento, CA
(916) 445-5716
Although the official name for the Division remains the "Division of Mines and Geology," in January 2002, the Department of Conservation's Director established its pseudonym as the "California Geological Survey" (CGS). The mission of CGS is to provide scientific products and services about the state's geology, seismology and mineral resources including their related hazards that affect the health, safety, and business interests of the people of California.
California Department of Transportation (Caltrans)
Office of Rigid Pavement Materials and Structural Concrete (ORPSC)
Sacramento, CA
(916) 227-7281
The ORPSC provides technical expertise, recommendations, and quality assurance testing for the cement, aggregate and concrete used in highway projects.
California Integrated Waste Management Board (CIWMB)
Sacramento, CA
(916) 341-6000
The CIWMB's mission is to reduce waste, promote the management of all materials to their highest and best use, and protect public health and safety and the environment, in partnership with all Californians. See the following on-line resources:
California Mining Association (CMA)
Sacramento, CA
(916) 447-1977
The CMA represents mining companies, including some aggregate companies.
Construction & Demolition Recycling Magazine
Cleveland, OH
(216) 961-4130
Construction & Demolition Recycling magazine is the official publication of the Construction Materials Recycling Association.
Construction Materials Association of California (CMAC)
Sacramento, CA
916-554-1000
The CMAC is the Northern California trade association for aggregate and ready mixed concrete producers, suppliers, and service providers from the Oregon border to Bakersfield. It is a non-profit member organization.
Contractors Register, Inc. -- Free Directory of the Construction Industry
The Blue Book of Building and Construction
Jefferson Valley, NY
(800) 431-2584
(916) 485-3832 (Sacramento representative)
Since 1913, The Blue Book of Building and Construction has been the construction industry's premier information source.
King County Environmental Purchasing Program
Seattle, WA
(206) 296-0100
(800) 325-6165
A pioneer and contemporary model in environmental procurement, King County maintains a Recycled Concrete Aggregate Web page.
United States Department of Transportation
Federal Highway Administration (FHWA)
Washington, DC
The FHWA is charged with the broad responsibility of ensuring that America's roads and highways continue to be the safest and most technologically up-to-date. See the following online resources:
United States Environmental Protection Agency (USEPA)
Washington, DC
(202) 272-0167
The mission of the USEPA is to protect human health and the environment. The following report is accessible from the USEPA's Web site:
- A Study of the Use of Recycled Paving Material, Report to Congress as specified in the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA), Report No. FHWA-RD-93-147, EPA/600/R-93/095. To locate this report online, go to the USEPA's National Environmental Publications Information System Publication Title Index Web page, and then choose the 600 Series.
[1] Kohler, Susan, 2004, California Non-Fuel Minerals-2004: California Geological Survey. Available at http://www.consrv.ca.gov/CGS/minerals/min_prod/non_fuel_2004.pdf.
[2] California Integrated Waste Management Board, 2004, Statewide Waste Characterization Study. Available at http://www.ciwmb.ca.gov/Publications/LocalAsst/34004005.doc.
[3] California Integrated Waste Management Board. Construction and Demolition Recycling, Recycled Aggregate Web page. Available at http://www.ciwmb.ca.gov/condemo/aggregate/default.htm. Accessed on 12-5-06.
[4] California Integrated Waste Management Board. Recycled-Content Materials Marketing Program. Recycled Aggregate fact sheet. Available at http://www.zerowaste.ca.gov/RCM/pdf/BroAggregate.pdf. Accessed on 12-1-06.
[5] California Integrated Waste Management Board. Construction and Demolition Recycling, Recycled Aggregate Web page. Available at http://www.ciwmb.ca.gov/condemo/aggregate/default.htm. Accessed on 12-5-06
[6] California Integrated Waste Management Board. Recycled-Content Materials Marketing Program. Recycled Aggregate fact sheet. Available at http://www.zerowaste.ca.gov/RCM/pdf/BroAggregate.pdf. Accessed on 12-1-06.
Special Note: Portions of the Environmentally Preferable Purchasing Best Practices Manual were borrowed or adapted from the Environmentally Preferable Purchasing Guide published by the Solid Waste Management Coordinating Board of Minnesota.
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