LOCAL UTILIZATION OF SCRAP TIRES
Information & Resource List

INTRODUCTION

Scrap tires are not the largest percentage of the waste stream, but they offer special challenges in handling that can make them extremely problematic when disposed of whole in landfills, stockpiles, or illegal dumps. Whole tires take up a large amount of space and can "float" to the surface after they are buried, breaching landfill caps. Scrap tires also pose an immediate threat to both the public health and safety and the environment. They provide excellent breeding conditions for disease carrying mosquitoes and rodents and offer the ever present potential for the environmental disaster of a tire pile fire. For these reasons, whole tires may no longer be disposed of in landfills in many states. Nationally, in an effort to support tire recycling, the trend is to ban the disposal of any tire material, not just whole tires. While all of the environmental mandates and imperatives are vitally important, the combined economic impact of compliance can be devastating to rural localities.

Scrap tires and scrap tire material have a number of very useful properties which offer numerous opportunities for beneficial utilization. Tire material is resilient, weatherproof, insulating, combustible, and bondable.

The purpose of this report is to identify and briefly describe beneficial utilization concepts for whole, split, cut, shredded, chipped, and crumbed tires. This report provides information on numerous utilization strategies and contact information for more in depth assistance on specific concepts that have the potential to have an impact on the beneficial utilization of tires and tire material.

SOURCE REDUCTION

In the "hierarchy" of integrated waste management, source reduction is the highest preferred strategy. The concept is "simply" to reduce the amount, or toxicity, of waste that is created in the first place. Tire manufacturing companies have been working to maximize scrap tire source reduction for decades. Arguably, their most effective accomplishment to date was the development and production of the steel belted radial tire. While it is true that the steel belted radial tire is probably one of the most ornery creations you will ever try to take apart, it is also true that if we still drove around on only bias ply tires, our scrap tire piles would by three or four times bigger than they are.

Even with the success of the steel belted radial, tire manufacturers continue their work to develop even longer lasting tires. Several major companies now produce a top-of-the-line tire with an 80,000 mile rating. Additionally, at least one tire manufacturer is working to create a tire that is not only long lasting, safe, and dependable, but will also be easier to recycle when it becomes a scrap tire.

While tire manufacturers continue to make major contributions to reducing the number of scrap tires, individuals can effectively contribute as well. Purchasing retreaded tires, modifying driving habits, and conscious attention to proper tire inflation and rotation are all relatively simple, yet very effective methods of prolonging the useful life of tires.

RETREADING

Reusing existing materials is the second highest priority after source reduction. Retreading reuses sound tire casings to produce a valuable product and extend the life of a major portion of the original tire three or four times over. The service provided by tire retreaders is a higher environmental "value" than recycling reusable casings as scrap rubber, prolonging the life of the major portion of the tire for its original purpose.

Unfortunately, the initial emphasis that was placed on recycling, at the local, state and federal level, contributed to source reduction and reuse being "overlooked" or not credited for the significant and effective role they play in a comprehensive waste management strategy. This situation is changing. The current active focus at the federal level and in many states is on source reduction and reuse as higher, more effective priorities than recycling.

WHOLE TIRE UTILIZATION

Because of the high cost of equipment capable of shredding, chipping or crumbing whole tires, whole tire utilization is a very important component of an integrated strategy to deal with scrap tires. For years, whole tires have been beneficially utilized in a number of creative ways including: tire swings, playground and athletic equipment, flower planters, and roof, silage, or tarp weights. Within the context of the current reality of millions of scrap tires stockpiled across the continent, the only down side to these utilization strategies is that they use relatively few tires and they last "forever", so there is very little "repeat business". Any whole tires used outside for these purposes should have a hole driled in them to allow any rain water to drain out of them and eliminate mosquito breeding grounds.

Recently, in order to address the huge numbers of scrap tires that exist and the cost of processing equipment, many new whole tire utilization concepts have been experimented with including: artificial reefs, highway and stream bank retaining walls and super insulated residential homes.

Earthships (houses constructed from scrap tires)combine the need for affordable, energy-efficient housing and scrap tire utilization into an innovative and effective construction method. Whole tires are positioned to form the back and side walls of the structure and are then rammed full of dirt (approximately three wheel barrows per tire). Subsequent rows are laid like overlapping bricks, and packed with dirt until the finished height of the wall is reached. The tire portions of the structures are single or multiple U shaped modules on one or more levels. If oriented and constructed properly, the thermal mass provided by the tire walls stabilizes indoor temperatures year round, reducing energy demands for both heating and cooling. The tire walls are finished with either adobe or stucco. "Conventional" construction methods provide the front and roof of the structure. Some new construction concepts create rounded structures with domed rooves.



For more information on Earthships check out their website at: www.

Earthworks: Whole tires packed with dirt can also serve effectively for retaining walls, hillside stabilization, wilderness steps, highway maintenance, and erosion control.

WHOLE TIRE UTILIZATION RESOURCES

Earthships

Solar Survival Architecture

Provides full information and support services, including architectural, design consulting, engineering evaluations, and videos for building Earthships.

Earthworks

Retiring
P.O. Box 505
Roy, Utah 84067

This booklet provides information and diagrams for over fifty projects utilizing scrap tires, from tire swings to erosion control berms.

Caltrans - Office of Transportation
Laboratory Research & Enviro-Chemical Services Branch
(916)739-2417 or (ATSS) 497-2417

or write to:
Transportation Laboratory
5900 Folsom Boulevard
Sacramento, California 95819

Translab Design Information Brochure #TL/REC/1/88 contains excellent design and implementation information on using whole tires for highway shoulder reinforcement and Channel Slope Protection

CUT TIRE UTILIZATION

Hand operated or automatic equipment capable of cutting tires is less expensive than shredding and grinding equipment. Utilization and market development concepts for cut tires include: door mats, gaskets, loading dock bumper guards, wheel chocks, railroad crossing mats, blasting mats, manhole collars, nursery collars, and heavy equipment mats.

In addition to their recreational use, inner tubes also offer an excellent "raw" material for the production of many creative and marketable products ranging from neck ties to saddle bags.

CUT TIRE UTILIZATION RESOURCES

University of Wyoming
Wyoming T² Center
Department of Civil Engineering
Box 3295
Laramie, Wyoming 82071-3295

Manhole collar repair - request T.I.P. Maintenance # 17 (July 93)

Retiring
P.O. Box 505
Roy, Utah 84067

This booklet provides information and diagrams for over fifty projects utilizing scrap tires, from tire swings to erosion control.

TIRE SHRED UTILIZATION
(4", 3", & 2" rough primary shred)

Rough shred has a number of beneficial utilization opportunities ranging from erosion control to septic line bedding. Each of these strategies focuses on one or more of the civil engineering properties of the tire shred.

The ARRC is researching the effectiveness of utilizing rough tire shred for erosion control, stabilization, alternative daily cover material in landfills, and subgrade fill.

Erosion Repair: This concept is for the repair of an area eroded by a one time situation or condition. The rough shred would be mixed with dirt and then used to fill the eroded area to within 6" of the surrounding surface level. The remaining 6" is filled with soil and seeded to repair the erosion damage. An example of a situation appropriate for an erosion repair project is a shallow slope eroded by heavy rains during construction work.

Soil Stabilization: This concept is to address an area that is likely to sustain erosion or slide conditions on a regular basis. The necessary function in this situation is to stabilize the soil and keep it from washing away . For this type of condition the rough shred would be mixed with soil and laid directly into the erosion or slide area. In severe situations the "light" fill would come to a level below grade and then be covered with a rip rap appropriate to the velocity and volume of the anticipated water flow.

Berms: Rough shred would be mixed with dirt (50%-50%) and then laid out where the berm is desired. A shallow trench should be dug to anchor the berm. The length and height of the berm would be determined by the specific project and basic engineering principles. The tire berm substructure would then be covered with a layer of 100% soil and seeded to stabilize the berm. The purpose of mixing the tire shred with the dirt is to afford channels throughout the berm substructure which can support root growth.

Subgrade Fill: For subgrade fill projects rough shred would be mixed with dirt and laid in the area that you wish to bring up to just below the finish grade. This can be used to fill a depression where a level area is desired or to build a light duty road bed. Mixing the shred with dirt will provide a more stable subgrade than using the rough shred alone. Where 2" X 2" tire chips are available they can be used directly in this application, without mixing with dirt. Again the subgrade tire fill should be covered with an appropriate top surface of gravel or dirt, depending on the project and the areas intended use.

Alternative Daily Cover: By mixing the rough shred 50-50 with dirt the product can be used as an alternative to the 6" dirt daily cover requirement on the working face of the landfill. This can significantly reduce the amount of dirt that needs to be brought in from other sites and can reduce the need to acquire new borrow sites.

TIRE SHRED UTILIZATION RESOURCES

Septic Drain Field Application

George Dalton
9416 Mini-Ranch Road
Waxhaw, North Carolina 28173

Has information available on and is active in the utilization of tire shred as a septic drain line bedding material.

Envirologic, Inc. 139 Main Street
Brattleboro, Vermont 05301

Prepared a report for the Vermont Department of Environmental Conservation on the "Use of Shredded Scrap Tires in On-site Sewage Disposal Systems

General Tire Shred Utilization Information

Pat Therrien
Appalachian Regional Recycling Consortium
6580 Valley Center Drive, Box 21
Radford, Virginia 24141
(540)639-9314
FAX (540)831-6093
E-mail: [email protected]

Jan Winsborough
The Tire Recycler's
Wyoming Tire, Inc.
P.O. Box 1400
Casper, Wyoming 82602
(307)235-0133

TIRE CHIP UTILIZATION
(3", 2", 1", 1/2", & 3/8" nominal chips)

Tire chips have an enormous range of local beneficial utilization opportunities. They work exceptionally well in all of the tire shred applications previously described. They can also be used as a substitute for aggregate in almost any subgrade application from an insulating backfill for concrete and block walls to road bed development. In addition to providing the same properties as conventional aggregates in subgrade applications, i.e. good drainage and stability, tire chips also have additional civil engineering properties in that they are resilient and provide insulation.

Biosolids Composting (Municipal Waste Water Sludge). Tire chips can be used to replace wood chips which "traditionally" have been used as a bulking agent for biosolids composting. Unlike wood chips, the tire chips will never need to be replaced because they do not break down in the composting process.

Insulating Backfill. Tire chips can be used in a backfill application for a block or concrete wall. They serve the same purpose as gravel, in providing the drainage that is needed. Additionally tire chips offer some insulation value that gravel does not provide.

Lightweight Fill. Tire chips mixed with various percentages of soil have been used in numerous projects such as subgrade fill for roadways and embankments, and under the footprint of a structure, paved parking lot, sidewalk, or similar application.

Compaction Resistant Systems. Using a patented process, 3/8" tire chips are mixed with compost and incorporated into athletic fields (REBOUND tm). This system provides an excellent growing medium for natural grass fields. The resiliency of the tire material in the mix, improves drainage, promoting excellent root growth and significantly reduces the degree to which the fields will compact.

TIRE CHIP UTILIZATION RESOURCES

Robert Eaton
U.S. Army Corps of Engineers
Cold Regions Research & Engineering Laboratory
72 Lyme Road
Hanover, New Hampshire 03755-1290

Offers numerous reports and documents on rubber modified asphalt and the use of tire chips as an insulating subgrade fill for gravel roads.

Dana Humphrey & Thomas Sandford
Department of Civil Engineering
5711 Boardman Hall
University of Maine
Orono, Maine 04469-5711
(207)581-2176
FAX (207)581-2202

Engineering report on the utilization of tire chips for lightweight fill and backfill.

TIRES, IN, ON, & UNDER THE ROAD

Whole tires and tire shred, chips and crumb have been demonstrated to contribute a number of beneficial properties to roads and highways.

Subgrade Fill.Tire shred and chips used as a subgrade fill material beneath gravel roads not only provides a stable base that drains well but also produces an insulating effect which reduces frost heave damage during the winter and "mud season" in the spring.

Projects using lightweight fill material for embankments and ramps have been successfully implemented in a number of states.

Tire Material in Asphalt. Several patented methods of mixing 1/2" and smaller tire chips with the "normal" aggregate in asphalt cement pavements have performed well in various tests and applications. These techniques for mixing tire chips with aggregate are generally referred to as "dry" methods. When utilized properly, the resilience of the tire material helps reduce cracking and allows the "flexible" surface to shed ice. Again, when utilized properly, roadways made from asphalt with tire chips incorporated in the mix can last from two to seven times as long as conventional pavement surfaces. Depending on the cost of the tire materials used in this process, the dry methods of incorporating tire material into asphalt pavement are not excessively more expensive than traditional asphalt mixes. Existing asphalt paving equipment capable of incorporating RAP (recycled asphalt pavement) can be used to blend in tire chips. As long as the total mix stays below 10% tire material, the resulting pavement can still be recycled.

Another method of utilizing tire material in asphalt pavement is to react very finely ground crumb rubber with the asphalt cement. This "wet" process is more expensive than traditional asphalt pavement. It also uses the least amount of tires per mile of highway of any of these methods. It should be noted, however, that while it is more expensive ton for ton, testing indicates that the thickness of the rubber-asphalt cement pavement can be reduced by as much as one half. The flexibility and bondability of the resulting pavement is also reported to last from two to seven times longer than traditional asphalt pavements. Additional benefits include noise reduction and a darker surface color, which is visually pleasing and warms faster to melt ice.

High Tech Adhesives & Compounds. A number of adhesives and patching compounds have been formulated which utilize some of the beneficial engineering properties of tire material.

Environmental and Technological Concerns. Leachate studies indicate that there is no significant environmental issue involved in the use of whole tire and tire shred, chip and crumb in subgrade applications.

It should be noted that a number of issues have been identified which need to be addressed before rubber modified asphalt, wet or dry, can be universally implemented. These issues include: rutting (from heavy truck traffic), scrunching (on downhill grades, from heavy trucks using their brakes), additional VOCs (volatile organic compounds) which raise regulatory concerns in non attainment areas, recyclability, and general failure which is frequently a result of incorrect application.

Cross Section of Tire Chip Test Road Bed in Richmond, Maine

study conducted by CRREL

ROADWAY UTILIZATION RESOURCES

Robert Eaton
U.S. Army Corps of Engineers
Cold Regions Research & Engineering Laboratory
72 Lyme Road
Hanover, New Hampshire 03755-1290

Offers numerous reports and documents on rubber modified asphalt and the use of tire chips as an insulating subgrade fill for gravel roads.

Clean Washington Center
Department of Trade & Economic Developmen
2001 Sixth Avenue, Suite 2700
Seattle, Washington 98121
(206)464-7040

Offers a wide range of reports documenting the use of recycled and recovered materials, including an evaluation of crumb rubber modified asphalt using the SHRP (Strategic Highway Research Program) protocols.

CRM Project
Technology Transfer Center
College of Engineering/257
University of Nevada
Reno, Nevada 89557
(702)784-1433
FAX (702)784-1429

The Crumb Rubber Modifier Technology News Brief is published and distributed as a service of this project. The News Brief offers excellent information on the latest development in CRM technology.

Asphalt Rubber Producers Group
3336 North 32nd Street, Suite 106
Phoenix, Arizona 85018-6241

Offers a wide range of technical information on asphalt rubber pavement.

Manhole Adjusting Contractors, Inc.
2300 Greenwood Avenu
P.O. Box 250
Monterey Park, California 91754
(213)725-1387 or (213)724-3577
FAX(213)725-7620

Offers information on results of specific comparative tests between asphalt rubber and other pavements.

National Asphalt Pavement Association
NAPA Building
5100 Forbes Boulevard
Lanham, Maryland 20706-4413
(301)731-4748
FAX (301)731-4621

TIRE DERIVED FUEL

Whole tires and tire material possess a significant capacity to burn. The heat value of tire material ranges from 14,000 to 18,000 Btu's per pound. By comparison, a good quality coal contains approximately 12,000 Btu's per pound. In the proper situation, whole tires and tire material can be effectively and efficiently used to produce heat which can be used for a number of applications, most frequently for the production of steam and/or electricity. Whole tires and tire material can also be used in certain types of cement kilns where both the thermal value of the tire and all of its component parts are incorporated into the finished product.

TIRE DERIVED FUEL RESOURCES

Tennessee Valley Authority
1101 Market Street
Chattanooga, Tennessee 37402-2801

TVA has performed a number of test burns at one of their fossil fuel power plants. Documentation of the results are available.

Malcolm Pirnie
6161 Busch Boulevard
Columbus, Ohio 43229

Produced a document titled Air Emissions Associated with the Combustion of Scrap Tires for Energy Recovery for the Ohio Air Quality Development Authority.

General Information & Industry Support Resources

The following individuals and organizations provide information and technical assistance on all of the scrap tire utilization techniques described in this report. Each of these people and organizations have provided time, energy, funding, research, and/or vision to bring us to where we are today regarding the way we view the issue of scrap tires and their beneficial utilization.

Michael Blumenthal
Scrap Tire Management Council
1400 K Street, N.W., Suite 900
Washington, D.C. 20005
(202)408-7781

The Scrap Tire Management Council offers excellent information on almost everything pertaining to scrap tires and their beneficial utilization.

Dana Arnold
U.S. Environmental Protection Agency
401 M Street
Washington D.C. 20460

EPA has a number of publications on beneficial tire utilization and evaluation data for leachate and air emissions.

Mary Sekora
Recycling Research Institute
P.O. Box 714
Suffield, CT 06078

Excellent resource! Publishes the Scrap Tire News, a monthly newsletter covering development in the scrap tire industry. RRI also produces the Scrap Tire Users Directory an annually updated reference book containing information on tire processors, equipment, haulers and brokers.