old report by us env tires

7/31/2019 Old Report by US Env Tires

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MARKETS FOR SCRAP TIRES

October 1991

United States Environm ental Protection Agency

Office of Solid Waste


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Disclaimer

Any m ention of comp any or p rod uct names in the report d oes not constituteendorsement by the Environmental Protection Agency.

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TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY

The Scrap Tire ProblemSource Reduction Alternatives

Recycling Alterna tivesTire to Energy AlternativesPyrolysis AlternativesBarriers to Increased Scrap Tire UtilizationOptions for Mitigating the Scrap Tire ProblemStud y Conclusions

CHAPTER 1- ASSESSMENT OF PRESENT SITUATION

INTRODUCTIONGENERATION OF WASTE TIRESENVIRONMENTAL PROBLEMS ASSOCIATED WITH WASTE TIRE

STOCKPILES

MosquitoesFire Hazards

SOURCE REDUCTION OF WASTE TIRESDesign ModificationsReuseRetreading

DISPOSAL OF WASTE TIRESWhole Tire DisposalShred ded Tire DisposalState Legislation Affecting Tire Disposa l

UTILIZATION ALTERNATIVESApplications of Whole Waste Tires

a) Artificial Reefs and Breakwatersb) Playground Equipmentc) Erosion Controld) Highway Crash Barriers

Applications of Processed Waste Tiresa) Splitting/ Punching of Tiresb) Manufacture of Crumb Rubber

from Scrap Tires1) Crumb Rubber in Rubber and Plastic

Products2) Crumb Rubber in Railroad Crossings3) Rubber Reclaim4) Crumb Rubber Additives for Pavements

(a) Rubber Modified AsphaltConcrete

(b) Asphalt-Rubber(c) Research and Demonst ration

of RUMAC and Asphalt-Rubber

iii

1

1

6788911

12

15

1516

18

182223232324252525262929293333333434

34

35353637

3738

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(d) Markets and Life Cycle Costof RUMAC and Asphalt-Rubber

c) Lightweight Road Construction Materiald) Playground Gravel Substitutese) Slud ge Comp osting

Combustiona) Power Plants

1) Modesto Power Plant2) Sterling Power Plant3) Erie Power Plant

4) Nevada Power Plantb) Tire Manufacturing Plantsc) Cement Kilns

1) Genstar Cement2) Arizona Portland3) Southw estern Portland

d) Pulp and Paper Production1) Tire-Derived Fuel SuppIy2) Use of Tire-Derived Fuel

e) Small Package Steam GeneratorsPyrolysis

a) Baltimore Therm al

b) J. H. Beers, Inc.c) TecSon Corporationd) Conrad Industriese) Firestone Tire& Rubber Com pan yf) The Oil Shale Corporation (TOSCO)

CHAPTER 2- MARKET BARRIERS TO WASTE TIRE UTILIZATIO N

INTRODUCTIONRUBBER ASPHALT PAVING SYSTEMS

Economic BarriersNoneconomic Barriers

COMBUSTIONEconomic Barriera) Power Plantsb) Tire-Derived Fuel

Non economic Barriersa) Power Plantsb) Tire-Derived Fuel

PYROLYSIS

CHAPTER 3- OPTIONS FOR MITIGATIN G TH E WASTE TIREPROBLEM

INTRODUCTIONREGULATORY OPTIONS--BASED ON EXISTING STATE PROGRAMSFunding Sources

a) Taxes or Fees on Vehicle Titles orRegistration

b) Taxes or Fees on the Sales of New Tiresor the Disposal of Old Tires

414243444546465151

525253555757585858596061

6161616262

63

63696970

7171717375757677

79

798081

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c) Fees on t he Perm itting of TireProcessing or Disposal Facilities,and the Use of State Bud getAppropriations

Identify and Clean Up Tire Dump sMethods for Managing Current Tire Disposal

a) Stockp ile Regulationsb) Processor Regulationsc) Hauler Regulations

Market Development Incentivesa) Rebates for Tire Recycling an d

Energy Usesb) Grants and Loans by State Governmentsc) Funds for Testing Innovative

Uses of Scrap TiresRegulations Regarding the Landfilling of Tires

OTHER REGULATORY AND NON-REGULATORY OPTIONSProcurement StrategiesResearchAdditional Coordination Among States and Localities

Education and PromotionWaste ExchangesTradeable CreditsTax Incentives

CHAPTER 4- CONCLUSIONS

REFERENCES

App end ix A-EPA REGIONAL OFFICES

App end ix B- STATE CON TACTS FOR WASTE TIRE PROG RAMS

Appen dix C - ADDITION AL SOURCES OF INFORMATION ONSCRAP TIRES

81

8181828282

8283

8384

858585868687

87888989

91

93

99

101

113

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Table

1

2

34567

89

1011

12

13

LIST OF TABLES

Scrap Tire Legislation StatusConten ts of Scrap Tire Legislation

Auto, Truck, and Farm Tire Shipm entsScrap Tire Generation in the United StatesMaterial and Energy Recovery from Scrap TiresEstimated Tire Shredding CostsCosts of Landfilling Automotive Waste Tires

in the United StatesScrap Tire Legislation StatusContents of Scrap Tire LegislationAsphalt-Rubber Applicator CompaniesComparison of Rumac and Asphalt-Rubber Costs

with Standard Asphalt Costs

Summary of Measured Emissions at the ControlDevice Outlet

Summary of Barriers to Solving Scrap TireProblem

vi

Page

45

17192127

28303140

43

50

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Figure

1

2

34567

LIST OF FIGURES

Flow diagram showing estimated destination ofscrap tires in 1990

Flow diagram showing estimated destination ofscrap tires in 1990

Destination of waste tires, 1990An integrated tire utilization systemSchematic of a tire incineration projectSchematic of cement manufacturing processTire feed system flow sheet

Page

3

202247485456

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MARKETS FOR SCRAP TIRES

EXECUTIVE SUMMARY

The management of scrap tires has become a growing problem in recent years.Scrap tires represent one of several special wastes that are difficult for municipalitiesto handle. Whole tires are difficult to landfill because they tend to float to thesurface. Stockpiles of scrap tires are located in many communities, resulting inpu blic health, environmental, and aesthetic pr oblems.

This repor t d iscusses the p roblems associated w ith scrap tires and identifiesexisting and potential source reduction and utilization m ethods that may beeffective in solving the tire problem. Barriers to increased utilization and optionsfor removing the barriers are identified and evaluated.

The Scrap Tire Problem

Over 242 million scrap tires are generated each year in the United States. Inaddition, about 2 billion waste tires have accumulated in stockpiles or uncontrolledtire dumps across the country. Millions more are scattered in ravines, deserts,woods, and empty lots. Scrap tires provide breeding sites for mosquitoes which canspread d iseases and large tire piles often constitute fire hazards. Most tire and solidwaste p rofessionals agree that a tire p roblem exists.

Six facets of the tire problem are listed below:

Tires are breeding grounds for mosquitoes. Besides the major nuisanceof mosquito bites, mosquitoes can spread several serious d iseases.

Uncontrolled tire dumps are unsightly and are fire hazards. Fires intire dumps have burned for months, creating acrid smoke and leavingbehind a hazardous oily residue. A few tire fire locations have becomeSuperfund sites.

Tires should be utilized to minimize environmental impact andmaximize conservation of natu ral resources. This means reu se orretread ing first, followed by reuse of the rubber to make rubberproducts or paving, and then combustion and disposal. At present, thepreferred uses do not accommodate all the tires, and disposal must beutilized to a large degree.

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Waste tires have to go somewhere. They tend to migrate to the leastexpensive use or d isposal op tion. As costs or d ifficulties of legaldisposal increase, illegal dumping may increase.

Disposing of waste tires is becoming more expensive. Over the past 20years the average tipping fees for disposing of tires have continually

increased. This trend is likely to continue as landfill space becomesmore scarce.

Tires take up land fill space. Whole tires are banned from manylandfills or charged a higher tipping fee than other waste; even if theyare carefully buried to prevent rising they are very bulky. Shreddedtires take up less space, but it is space that could be saved if the tireswere u tilized as raw material for produ cts or as fuel.

As described above, the continuing accumulation of waste tires has led to sixconcerns of varying severity. Clearly, the mosquito and fire hazard problems are the

most serious of the concerns listed. Controlling them in the near term willnecessitate providing adequate safeguards on existing stockpiles. Ultimately,decreasing the waste tire accumulations will involve appropriate uses of recycling,combustion, and land filling. The curren t trend s of reuse an d sou rce redu ctionindicate that the quantity of tires utilized in products is likely to remain smallerthan the quantity combusted or landfilled in the future.

It is estimated that less than 7 percent of the 242 million tires d iscard ed in1990 were recycled into new p roducts and about 11 percent w ere converted intoenergy. Over 77 percent, or abou t 188 million tires p er year, were land filled,stockpiled, or illegally dumped, and the remaining 5 percent were exported. The

flow of scrap tires is shown in Figure 1.

Scrap tire legislation is increasing rapidly at the state level. In 1990, twelvestates passed or finalized scrap tire laws, regulations, or amendments. As of January1991, thirty-six now have scrap tire law s or regu lations in effect, and all but 9 statesregulate or have bills being proposed to regulate tires. A summary of the stateslaws in effect in January 1991 are listed in Table 1. The contents of the legislationsand the sources of fund ing are sum marized in Table 2.

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4 2 .2 Waste Tire Inventory q

1 7 . 4 %

1 8 7 . 8 I 7 7 .6 % I

2 5 .9 1 0 .7 %

Combustion1. Power plants2. Tire plants3. Cement plants4. Pulp and paper mills5. Small package boilers

0 .31

0 .1 %

Whole Tire Applications

1. Reefs and breakwaters2. Playground equipment

3. Erosion control

4. Highway crash barriers

16 . 0 6 .6 %

w

Processed Tire Products1. Processed rubber products2. Crumb rubber for pavements3. Playground gravel

substitute4. Sludge composting5. Split tire products

Figure 1. Flow diagram showing estimated destination of scrap tires In 1990.

(In millions of tires and percent)

Retreads (33.5 million) and reused tires (10 million) are not counted as scrap tires.

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Alabama

Alaska

Arizona

Arkansas

California

ColoradoConnecticutDelaware

Florida

GeorgiaHawaii

Idaho

Illinois

Indiana

Iowa

Kansas

KentuckyLouisiana

Maine

Maryland

Massachusetts

MichiganMinnesotaMississippi

Missouri

Table 1SCRAP TIRE LEGISLATION STATUS

January, 1991

Draft Proposed Regs Lawx

xx

x

x x

x

xx

x

x

x

xxxxxx

Draft - draft being written/bill in discussionProp - proposed/introduced in 1990 legislature

Rags - regulated under specific provision of solid

Law - scrap tire law passed

Source: Scrap Tire News, Vol.

xx

MontanaNebraska

Nevada

New HampshireNew Jersey

New MexicoNew York

North Carolina

North DakotaOhio

OklahomaOregon

PennsylvaniaRhode Island

South Carolina

South DakotaTennesseeTexas

UtahVermont

Virginia

WashingtonWisconsinWest Virginia

x Wyoming

Draft Proposed Regs Law

5, No. 1, January 1991

waste or other laws (e.g., automotive wastes)

x

x

xx x

x

x

x

x

x

x

xxxx

xx

x

xx

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Table 2CONTENTS OF SCRAP TIRE LEGISLATION

Funding Storage Processor Hauler Landfill MarketSource Rags Regs Regs Restrictions* Incentives

2% sales tax on retail sale x x$0.25/tire disposal fee

ArizonaCaliforniaColoradoConnecticutFloridaIllinoisIndianaIowaKansas

KentuckyLouisianaMaineMarylandMichiganMinnesotaMissouriNebraska

x xx x

x

x x x x

x x xx x

x

R&D grantsgrants/loans

grants

$1.00/tire retail sales$0.50/vehicle title feepermit feed/tire storage sites

x

xx x x$0.50/tire retail sales

$1 .00/tire retail sales

grants

xx

x x

x x draft grants/loans$1.00/tire disposal fee

state budget appropriations

$0.50 vehicle title fee

$4.00/vehicle title transfer

$0.50/tire retail sales$1 .00/tire retail sales

x

x

x

x

x

x

x

x

x

x

x

grants

grants

funds/testing

grants

x

x

x

x

New Hampshire graduated vehicle regist. feeNorth Carolina 1% sales tax on new tires

Ohio

Oklahoma $1 .00/new tire (surcharge)

Oregon $1.00/new tire (dspl tax)

Pennsylvania

Rhode Island $0.50/new tire sales tax

South Dakota

Tennessee

Texas

Utah graduated tax per tire size

Vermont

V irg in ia $0.50/new tire (dspl tax)

Washington

Wisconsin $2.00/tire vehicle title fee

funds/collectionx x x

x

x

x

x

x

x

x

x

x

x

grants

$0.01/lb

R&D grants

x

x

x x

xx

xx

x

$20/ton

funds/testing

x

x

x

x

x

x

grants

$20/tonx

The maiority of states have imposed regulations that require tires to be processed (cut, sliced, shredded) prior to Landfilling..Some of the states allow for storage (above ground) of shreds at landfills. OH, NC, CO are among the states considering or allowing

monofils for tire shreds. Whole tires are discoraged from landfills (in almost all cases) either by law (e.g., MN) or more

frequently by high disposal fees.

Source: Scrap Tire News, Vol. 5, No. 1, January 1991.


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Source Reduction Alternatives

Source reduction measures for tires include the following:

Design of extend ed life tires

Reuse of used tires Retreading

Great strides have been mad e in the last 40 years in tire manu facturing that havemore than doubled the usefu l life of tires. Forty thousan d m ile tires are comm on-place, and 60,000 to 80,000 mile lifetimes are often achieved. Constraints of cost, fuelconsumption, and comfortable rides, make it unlikely that any major designchanges will occur in the near future that will significantly increase tire life.

Frequently, when one or two tires of a set are worn, the entire set is replacedwith new tires. Useful tread may rem ain on several of the rem aining tires. Thesetires are often sold for second cars or farm equipment. About 10 million tires peryear are currently being reused. Although the reuse of partially-worn tires cannot beexpected to solve the tire problem, reuse could potentially d ouble based on thenumber of good tires currently thrown away,

Retreading is the application of a new tread to a worn tire that still has a goodcasing. There are currently over 1,900 retreaders in the United States and Canada;however, that num ber is shrinking because of the d ecreased markets for passengerretreads. This decline is primarily du e to the low price of new tires and thecomm on m isperception that retread s are unsafe. The price of inexpensive new

passenger tires ($50 to $60) is often a t or near the p rice of quality retread s. On theother hand, truck tire retreading is increasing. Truck tires are often retreaded threetimes before being discarded and the truck tire retreading business is increasing,

The National Tire Dealers and Retreaders Association asserts that properly-inspected retreaded tires have lifetimes and failure rates comparable to new tires,Mileage guarantees and / or war ranties for retreads are often similar to or identical tonew tire warranties, In 1987, about 23 million passenger and light truck tires and 14million truck tires were retreaded, By 1990 these retread rates changed to 18.6million and 14,9 million, respectively, It is estimated that most good truck tire

casings are being retreaded d ue to th e high cost of new truck tires, but that at leasttwo times as many p assenger and light truck tires wou ld be suitable for retreading.

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Recycling Alternatives

Som e recycling alternatives use wh ole tires, thus requ iring n o extensiveprocessing; other alternatives require that tires be split or punched to makeproducts; and still other alternatives involve tires that are finely ground enabling

the manufacture of crumb rubber products. Some applications for each alternativeare listed below

Whole tire applications Artificial reefs and breakwaters Playground equipment Erosion control Highway crash barr iers

Split or punched tire applications

Floor mats, belts, gaskets, shoe soles, dock bum pers, seals, mufflerhangers, shims, washers, and insulators

Shredded tire applications Lightweight road construction material Playground gravel substitutes Sludge comp osting

Ground rubber applications Rubber and plastic prod ucts; for example, molded floor mats,

mud guards, carpet padding, and plastic adhesives

Rubber railroad crossings Additives for asphalt pavements

All of the tire recycling alternatives listed above are being used to varyingdegrees. However , the total usage of tires for recycling cur rently is estimated to beless than 7 percent of the annual generation. The markets for most of the p rodu ctsmay be increased, but, even if increased to their fuIlest potential, appear to be smallcomp ared to the nu mber of tires generated each year. Ground rubber ap plicationshold the greatest promise. The tire recycling alternative with the greatest potentialto significantly reduce the scrap tire problem of the United States is in asphalt

highway construction.

There are two types of processes for using crumb rubber in pavements. Oneapplication, referred to as rubber modified asphalt concrete (RUMAC), involvesreplacing some of the aggregate in the asphalt mixture with ground tires. Thesecond , called asphalt-rubber, blends/ reactivates a certain percentage of the asphaltcement with ground rubber. Both systems are being evaluated by state agencies aswell as the federal government.

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Tire to Energy Alternatives

Tires have a fuel value of 12,000 to 16,000 Btu per pound, slightly higher thanthat of coal. With existing technology, tire combustion can meet Federal and Stateenvironmental requirements. Tires may be bu rned wh ole or shredd ed into tirederived fuel (tdf). Whole tire combustion requires less processing expense;

how ever, most of the plants currently burn ing tires for fuel do not have thecapability to burn whole tires. In 1990, about 25.9 million tires (10.7 percent of to talgeneration) were burned for energy produ ction. Combustion facilities currentlyusing tires as fuel include:

Power plants Tire manu facturing plants Cement kilns Pulp and p aper plants Small package steam generators

The largest scrap tires combustion system is the Oxford Energy plant inModesto, California. It consumes about 4.9 million tires per year and generates 14MW of pow er. A second Oxford Energy p ower p lant, designed to burn about 9-10million tires per year , is un der construction in Connecticut. Comm ercial operationis planned for 1991.

Seven cemen t kilns in the United States u tilize about 6 million scrap tires p eryear to replace conventional fuels. Cement kilns appear to be ideal for scrap tiresbecause of their high operating tem peratures (2,600 F) and good conditions forcomplete combustion, which minimize air pollution p roblems. Also, there is noresidue, since the ash is incorporated into the cement product. Of the 240 cementkilns in the United States, about 50 are equipped with precalciner/ preheaters,making them most suitable for tire combustion.

Many furnaces designed to burn wood chips at pu lp and p aper plants aresuitable for bu rning tire-derived -fuel w ithout m ajor m odifications. Frequently,only w ire-free tdf can be used in these boilers, thus increasing th e tire processingcosts. An estimated 12 million tires per year are currently being consumed by thepulp and paper industry.

Pyrolysis Alternatives

Pyrolysis of tires involves the application of heat to produce chemical changesand derive various products such as carbon black. Although several experimentalpyrolysis units have been tried, none has yet demonstrated su stained comm ercialoperation.

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Barriers to Increased Scrap Tire Utilization

Barriers to increased scrap tire utilization can be classified into two maintypes - economic and noneconomic.

Economic barriers refer to the high costs or limitedrevenues associated with various waste tire utilizationmethod s w hich m ake the u ses unp rofitable. Tireprocessors w ill not invest time or capital unless there is a sufficientrate of return to justify the efforts.

Non economic barriers refer to a nu mber of constraints on u tilization.These include technical concerns such as lack of technical informationor concerns regarding the quality of products or processes. Thesebarriers also include the reluctance of consum ers, processors, andregulators to employ new approaches or technologies for aesthetic orother reasons. They also include constraints on u tilization because ofhealth and safety, environmental issues, laws, and regulations.

The strength and persistence of these barriers are evident from thecontinuing buildu p of tire stockpiles and dum ps over th e last several years.

Most of the technologies available for mitigating the nations scrap tireproblem are limited by both economic and noneconomic barriers, and it is oftendifficult to separate the two. For example, the use of retreaded or used au tomobiletires is limited by competitive new tire prices, an economic barrier, as well as

consumer concerns about safety and reliability, a noneconomic barrier. Designingtires to last 100,000 miles or more would cost considerably more and also wouldlikely result in rou gher rid es and more tire noise.

Making p rodu cts such as reefs, playground equipm ent, floor mats, gaskets,etc., out of scrap w hole or processed scrap tires is primarily limited by the high costof tires compared with other raw materials. However, there are also somenoneconomic barriers. Reefs made of tires, for example, are not appropriate for therough shores of the northw est, Playground equipm ent mad e of wood or otherproducts is often preferred for aesthetic reasons.

The two technologies w ith the most potential for using a major portion ofscrap tires generated each year, and actually redu cing the tire stockpiles, arepavements with rubber additives and combustion for energy generation.

Barriers to the increased usage of rubber in asphalt pavements are botheconom ic and noneconom ic in natu re. The cost of installing road s of rubberizedasph alt is greater than conventional asph alt, which is an econom ic barrier. On theother hand, several studies show that the total life cycle cost of rubberized asphalt is

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lower than conventional asphalt. This would be an economic benefit. However,decisions on paving are often mad e on the basis of road miles paved per year, ratherthan life cycle cost of the pavement.

The two forms of rubberized asp halt that have been tested the longest,asphalt-rubber and PlusRide

TM, are patented. The required royalty fees increase the

cost of these produ cts. Although, initially, patents may have stimu lated the growthof these produ cts, they now app ear to rep resent an economic barrier to increasedscrap tire u sage by these technologies. The p atent for aspha lt-rubber expires in 1991.After that m ore comp anies are expected to become involved, resulting in lowercosts. Non-patented rubberized asphalt roadw ays are also being tested.

One of the m ajor non econom ic barr iers to the use of ru bber in asph altpavements has been the lack of consensus on the results of long-term testing. Manylong-term tests have been performed, but they were performed in over a dozenstates, and as yet these tests have not been brought together and evaluated in a

cohesive study.

Power plants to burn scrap tires involve large capital investments and annualoperating expenses. However, plants located near large supplies of tires can befeasible. A key variable in determining economic feasibility for these plants is thebuy-back rate gran ted by the u tility. In areas of the country w here the rate is high,such as California and the northeast, power plants are feasible. The buy-back rate isthe rate the utilities pay for electricity generated from alternative fuel, and reflectsthe fuel and other costs avoided by the u tility.

Burn ing tires in existing pu lp and pap er mills and certain types of cement

kilns requires much less capital investment than the dedicated power plantsmentioned above. Pulp and paper mills often burn hog-fuel (chipped wood), thusrequiring very little modification for tire chips. The main economic variable is theprice of the comp eting fuel. Tire-derived fuel mu st often comp ete with low costcoal or petroleum coke, a waste p rodu ct from the p etroleum refining process. If tdfis only slightly cheaper than the alternate fuel, then plant modification cannot be

justified .

The main non economic barriers to scrap tire combustion are the timerequired for permitting a p lant and the concerns of neighbors regarding

environmental, health, and safety issues. Because of the test burns required andtime delays in permitting, many cement plant and pulp and paper mill operatorshesitate to change their operation for the small savings realized by burning scraptires.

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Other means of exchanging information such as conferences on scrap tires,hotlines, newletters, waste exchanges, and computerized data bases, are beingdeveloped or utilized by both government and industry. Because the economicsand technology of scrap tires is changing so rap idly, these sources are part icularlyhelpful in spreading information regarding scrap tires, to government officials,

entrepreneu rs, environm ental group s, and private citizens.

Study Conclusions

Each year about 242 million tires are scrapped. Current trends indicate thatless than 7 percent of these tires are being recycled as prod ucts and 11 percent arebeing burned for energy, and 5 percent are being exported. The rest are beinglandfilled, stockpiled, or dumped illegally.

EPA wishes to encourage waste tire reduction and recycling, with a specialemp hasis on reducing the nu mber of tires in uncontrolled stockpiles or illegaldum ps. These tires are often sites of mosqu ito infestation, with the p otential forspreading dan gerous mosquito-borne d iseases. Large tire dum ps can also lead tofires with major releases of hazardous organic chemicals into the air, surface water,and ground water.

Recycling rubber from tires for use in asphalt pavements is a promisingtechnology. Asphalt pavements incorporating tire rubber are claimed to have twicethe lifetime of ordinary asphalt, but they can cost twice as much. Pavements withcrumb rubber additives consume over one million tires per year now, and bothasphalt-rubber and rubber m odified asphalt concrete have considerable potential for

expansion. If Federal, state, and local governments prom ote much broad er use anddemonstration of this technology, perhaps the technical issues will be resolved andusage will expand.

Using whole tires as fuel for reciprocating grate power plants appears to beeconomically feasible in some regions of the coun try, and can meet environm entalpermitting requ irements, One su ch plant in Mod esto, California, is curren tlyconsuming 4.9 million tires per year. Another power plant is under construction inConnecticut and is expected to consume an additional 10 million tires per year. Asecond 10 million tire per year plant is being planned for an area near Las Vegas,

Nevada. The main barriers to such plants appear to be local resistance toincineration projects and lengthy permitting procedures.

The rep lacemen t of coal by tire-derived-fuel appear s economically feasible forcement kilns. Seven su ch kilns are cur rently op erating in the U. S., consum ing theequ ivalent of abou t 6 million tires per year between them . There is poten tial forthis use to expand further, particularly for those cement kilns whose feed systemsare compatible with the use of TDF.

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Tire-derived fuel is economically feasible for use in hog fuel boilers in thepulp and paper industry. It is estimated that the equivalent of 12 million tires isconsum ed an nu ally in this way in th e U.S. There is poten tial for this use to expan dfurther.

Other technologies and options are p romising on a smaller scale, but also are

imp ortant to the overall solution. Uses of crumb rubber for such diverse productsas athletic sur faces, tracks, and rubber molded produ cts, show potential for grow th.Also, increased retreading could utilize a significant number of tires. If the market

justified retreading all th e usable carcasses, abou t 20 million ad d ition al passengerand light tru ck tires could be retreaded each year. Curren t trend s, how ever, indicatethat fewer of these tires are retreaded each year.

Other uses of tires are sometimes feasible for specialized geographicconditions. Cape May Cou nty, N ew Jersey uses 100,000 tires per year, which is 100percent of its scrap tires, for ar tificial reefs. The State of Minnesota has used abou t a

million of its tires since 1986 for roads in swampy areas.

The markets for most other products made from tires have potential, butappear to be relatively small, These include rubber railroad crossings, artificial reefs,playground equipment, erosion control, highway crash barriers, playground gravelsubstitute, sludge composting, rubber farm and agricultural equipment, and rubbermats. Each of these products has the potential for using some portion of our wastetire stockpile. Collectively, they are all important parts of the solution to the tireproblem.

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Chapter 1

ASSESSMENT OF PRESENT SITUATION

INTRODUCTION

About 242 million automotive, truck, and off-road tires are discarded in theUnited States each year. This is approximately equal to one waste tire per person peryear. Additionally, there are 33.5 million tires that are retreaded and an estimated 10million that are reused each year as second-hand tires. It is estimated that 7 percentof the d iscarded tires are currently being recycled into new produ cts and 11 percentare converted to energy. Nearly 78 percent are being landfilled , stockpiled, orillegally dum ped, w ith the remainder being exported.

Tires are difficult to landfill. Whole tires do not compact well, and they tend

to work their way up through the soil to the top. As a result, tire stockpiles, whichcost less than landfills, have sprung up all over the country. It is estimated thatbetween 2 and 3 billion tires are stockpiled in the U.S. at present, with at least onepile containing over 30 million tires. Tire stockpiles are unsightly and are a threatto public health and safety. Not only are tire piles excellent breeding grounds formosquitoes, but they are also fire hazards.

It is the goal of the EPA to eliminate illegal dumping altogether and to reducethe stockpiling and landfilling of discarded tires as much as possible. The report,The Solid Waste D ilemma: An Agend a for Action, lays out EPAs nat ional strategyfor m anaging mu nicipal solid w aste (MSW) (1). It sets out a three-tier hierarchy for

management of municipal solid waste, with source reduction ranking first, followedby recycling, then incineration and land disposal. Interestingly enough, over the last40 years, tires have been somewhat of a success story for source reduction. Theadvent of the 40,000-mile tire means that tires last longer before they wear out.

As with m any other components of the waste stream, the highest priorityoptions, source reduction and recycling, are the least utilized and landfilling is themost common practice. Potential source reduction measures for tires include thedesign of longer lived tires, reuse of tires removed from vehicles, and retreading.These practices all extend the u seful life of tires before they are d iscard ed.Considerable increases in t ire lifetimes h ave been achieved in the past 20 years w ith

the advent of the radial tire. On the other hand, partially because of the radial tires,retread ing of autom obile tires is decreasing each year. Radial tire side walls tend tobe weaker than bias ply walls, thus th e rejection rate by retreaders is h igher. Radialsalso are more expensive to retread than bias plies. Truck tire retreading, however, isstill increasing. A tota l of about 37 million tires w ere retr ead ed in 1987. Thisdropped to 33.5 million in 1990. Retread ing extends the useful life of a retreadable

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tire from 60 to 80 percent (an au tomobile tire w ith one retread ) to 300 percent (atruck tire with three retreads).

Tire recycling activities includ e the use of whole tires or processed tires foruseful pu rposes. Whole tire app lications include reefs and breakwaters, playgroundequipment, erosion control, and highway crash barriers. Processed tire productsinclude mats and other ru bber products, rubberized asphalt, playground gravel

substitute, and bulking agent for slud ge comp osting.

Scrap tire combustion is practiced in power plants, tire manufacturing plants,cement kilns, pu lp and pap er plants, and small package steam p lants.

GENERATION OF WASTE TIRES

It is comm only accepted in the tire ind ustry that abou t one tire per person p eryear is discarded . Since there is no industry grou p or governm ental agency thatmonitors tire disposal in the United States, the best estimates that can be made are

based on tire production. The Rubber Manufacturers Association (RMA) records thenu mber of original equipm ent, replacement, and export tires that are shipp ed eachyear in the United States. (See Table 3.) In 1990, a total of 264,262,000 tires wereshipped . The RMA data includ e new tire imp orts, but not imp orted u sed tires. Toestimate the number of tires that were discarded in the United States in 1990, thefollowing assumptions were made:

One tire is discarded for each replacement tireshipped , includ ing new an d used imports. (Discard isassumed to be in the same year as replacement tireproduction.)

Original equipm ent tires are not d iscarded inthe year they are prod uced, but rather in theyear a rep lacement is sold.

Exported tires are not discarded in the USA.

Four tires are discarded for each automobile ortruck when it is taken out of service.

Retreads and reused tires are put back into

service in the same calendar year that they weretaken out. (Therefore, retreading and reuse simplyhave the effect of extending the tires useful life.)

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Table 3U.S. AUTO, TRUCK, AND FARM TIRE SHIPMENTS*

1990

Original equipmentReplacementExport

Totals

1989

Original equipmentReplacement

ExportTotals

1988


Totals

1987


Totals

1986


Totals

(In thousands of tires)

Passenger

47,199152,251

14,110213,560

51,170151,156

12,437214,763

54,131155,294

9,365218,790

52,913151,892

5,987210,792

54,392144,267

4,032202,691

Bus/Truck

6,99336,588

3,28346,864

8,17735,172

3,54846,897

8,80133,918

3,30146,020

7,84534,514

2,06944,428

6,85932,392

1,30240,553

Farm

Equipment

9952,549

2943,838

8902,664

2703,824

7532,662

2673,682

6082,658

2263,492

5122,319

1703,001

qIncludes imported new original equipment and replacement tires.

Total

55,187191,388

17,687264,262

60,237188,992

16,255265,484

63,685191,874

12,933268,492

61,366189,064

8,282258,712

61,763178,978

5,504246,245

.Source: Rubber Manufacturers Association (RMA) Monthly Tire Report,

December 1990 and earlier years.

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Replacement Tire Shipments

Passenger 1/

Truck 1/

Farm Equipment 1/

Imported Used Tires 2/

Total Replacement Tires

Tires from Scrapped Vehicles 3/

Cars

Trucks

Total Tires from Scrapped Vehicles

Total Scrap Tires in U.S.

U.S. Population (thousands) 3/

Scrap Tires/Person/Year

Table 4

SCRAP TIRE GENERATION IN THE UNITED STATES(In Thousands)

Year1964 1985 1986

144,580 141,455 144,267

31,707 32,098 32,392

2,592 2,395 2,319

1,793 3,233 2,552

180,672 179,181 181,530

26,700 30,916 33,768

6,406 8,400 9,236

33,108 39,316 43,004

213,780 218,497 224,534

235,961 238,207 240,523

0.91 0.92 0.93

1987

151,892

34,514

2,658

2,925

191,989

32,412

9,456

41,866

233,857

242,825

0.96

155,294

33,918

2,662

1,352

193,226

35,016

9,004

44,020

237,246

245,807

0.97

1989 1990

151,156 152,251

35,172 36,588

2,664 2,549

1,466 1,108

190,458 192,496

37,200 4/ 39,000 4/

10,400 4/ 11,000 4/

47,600 50,000

238,058 242,496

247,732 249,981

0.96 0.97

1/ (Includes imported new tires) National Petroleum News, Fact Book, 1986-1986. Data from the Rubber Manufacturers

Association. 1986 through 1990 data from RMA Industry Monthly Tire Report, December 1989 and December 1990.

2/ U.S. Department of Commerce. U.S. Imports for Consumption. (FT246). 1984-1990.

3/ U.S. Department of Commerce, Statistical Abstracts, 1990 and prior years. Estimate based on 4 tires per vehicle.

4/ Estimated by Franklin Associates, by linear extrapolation.


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Figure 2. Flow diagram showing estimated destination of scrap tires In 1990.

(In millions of tires and percent)

* Retreads (33.5 million) and reused tires (10 million) are not counted as scrap tires.

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Table 5

MATERIAL AND ENERGY RECOVERY FROM SCRAP TIRES

Method of Recovery

Energy/Burning

Reclaim

Splitting

Crumb Rubber for Pavements

Other Crumb

Whole Tires

Total Recovered

Used Export

Landfill, Stockpile andDumping

Total Scrap Tires*

No. of Tires(in millions)

25.9

2.9

2.5

2.0

8.6

0.3

42.2

12

188

Percentage of 242Million Scrap Tires

10.7

1.2

1.0

0.8

3.6

0.1

17.4

5.0

77.6

242 100.0

qRetreads (33.5 miilion) and reused tires (10 million) are notcounted as scrap tires.

Source: Franklin Associates, Ltd. and Dr. Robert Hershey. Estimatesbased on published data and technical discussions.

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Figure 3: Destination of Waste Tires, 1990

Sources: Table 5

are to d rill holes in the tires so that the water d rains or to remove the tire bead andturn the carcass inside out. This has been practiced on a small scale by individuals(3).

Fire Hazard s

For as long as it has been know n that w aste tires harbor m osquitoes, it hasbeen known they pose a fire hazard. Tire fires are particularly bad because of thedifficulty in extinguishing them. This is because of the 75 percent void space presentin a w hole waste tire, which makes it d ifficult to either qu ench the fire with w ater orcut off the oxygen supply. Water on tire fires often increases the production ofpyrolytic oil and provides a mode of transportation to carry the oils off-site andspeed up contamination of soils and water,

The potential fire hazard presented by waste tire stockpiles has been realized anu mber of times in the past decade. Several stockp iles have burned un til their tiresupplies were exhausted w hich, depend ing on weather conditions, may be a fewdays to more th an a year. Air p ollutan ts from tire fires includ e dense black smokewhich impairs visibility and soils painted surfaces. Toxic gas emissions includepolyaromatic hydrocarbons (PAHs), CO, S02, N 02, and HC1. Following tire pile fires,oils, soot, and other materials are left on site. These tire fire by-products, besidesbeing u nsightly, may cause contamination to surface and subsurface water as

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well as the soils on w hich the tires were located.dollar cleanu ps are sometimes requ ired to avoid(2).

For these reasons, multimillionfurther environmental problems

If stockpiles for waste tires are carefully monitored , the fire hazard can bereduced. Shredded tires pose less of a threat for fires. Tire shreds behave differentlythan whole tires when burning and because they have less air space, they can beextinguished more easily by allowing water to smother the fire (4). Other

precautions that m ay redu ce the fire hazards of tire stockpiles are m andatory firelanes and fire plans so that a fire can be attend ed to as qu ickly as possible (3).

Ultimately, the best solution to the problems of waste tires as fire hazards andmosqu ito breeding ground s is to eliminate stockpiles. At the least, the nu mber oftires in a stockpile should be m inimized, thu s redu cing the num ber of breeding sitesfor mosquitos and fuel for fires.

SOURCE REDUCTIO N O F WASTE TIRES

There are two options for reducing the number of tires landfilled, stockpiled,

and dumped. One is to increase recovery, which is discussed later in this report, andthe other is to reduce the number of tires generated in the first place (sourcered uction). Source reduction measu res that have limited poten tial for reducing thenumber of tires to be disposed includ e:

Design of extended life tiresReuse of used tiresRetreading.

Design M odifications

Great strides have been made in the last 40 years in tire manufacturing thathave more than dou bled the u seful life of tires. Fur ther increases in life wou ldrequire higher pressure, thicker treads, or less flexible materials. Each of thesemethod s would result in more gas consum ption, higher cost, and / or rougher rides.Cur rently steel-belted rad ial passenger tires last abou t 40,000 miles. If these tires areproperly inflated, rotated, and otherwise cared for, 60,000 to 80,000 mile lifetimesmay be achieved. It is not expected that any major design changes will occur in thenear futu re that w ill significantly increase tire life (5).

Reuse

Frequently, when one or two tires of a set are worn, the entire set is replacedw ith n ew tires. Useful tread may remain on one, two, or three of the tires removed.Many tire stores and tire haulers sort out the usable tires for resale. Virtually everymajor city in the USA has stores that sell used tires. These tires are often sold forsecond cars or farm equ ipment.

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Although the reu se of partially-worn tires cannot be expected to solve thescrap tire problem in th e USA, it has been estimated that a m inimu m of oneadditional year of tire life can be achieved out of 25 percent of the tires removedfrom vehicles (6). Assuming this to be the case, then the reduction of the scrap tireproblem by the reuse of used tires can be estimated. Suppose a set of four tires isremoved after 40,000 miles. If 25 percent (one tire), on average still has a usefultread of 10,000 miles left, this is equivalent to the set of four tires lasting 42,500 milesinstead of 40,000, an increase in life of 6 percent. It is not known how many goodused tires are curren tly being reu sed, but based on contacts with several tire stores, itis evident that a significant portion (estimated 50 percent) of the good used tires arecurrently being reused. If the other 50 percent were also used, a 3 percent reductionin tire d isposal could be realized.

Retreading

The third source reduction measure which can extend the u seful tire life, andtherefore redu ce the number of tires scrapp ed, is retreading. Retreading is the

app lication of a new tread to a w orn tire that still has a good casing. Retreadingbegan in the 1910's and has always played a role in the replacement tire market.There are currently over 1,900 retreaders in the United States and Canada; however,that n um ber is shrinking because of the d ecreased m arkets for passenger retreads.Truck tires are often retreaded three times before being d iscarded and the tru ck tireretreading bu siness is increasing. On the other hand , passenger tire retreading isdeclining. This decline is primarily due to the low price of new tires and thecomm on perception that retread s are unsafe. The price of inexpensive newpassenger tires ($50 to $60) is often at or near the price ofquality retreads.

The National Tire Dealers and Retreaders Association claims that properly-inspected retreaded tires have lifetimes and failure rates comp arable to new tires.Mileage guarantees and / or warranties for retreads are often similar to or identical tonew tire warranties.

In 1987, about 23 million passenger and light truck tires and 14 million trucktires were retreaded. By 1990, the passenger and light truck retreads dropped to 18.6million w hile truck retreads increased to 14.9 million (7). It is estimated that mostgood tru ck tire casings are being retreaded d ue to the high cost of new tru ck tires, butthat at least tw ice as many p assenger car and light tru ck tires wou ld be su itable forretread ing. While retread ing w ill not by itself solve the n ations tire problem,growth in retreading would reduce the number of new replacement tires neededeach year and, therefore, reduce the number requiring disposal. For example, if themarkets could be developed so that all the passenger and light tru ck tires suitable forretreading w ere actually retreaded , then about 20 million fewer n ew replacementtires would be needed annually. This would reduce the number of waste tiresgenerated per year by almost 10 percent.

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DISPOSAL OF WASTE TIRES

The removal of waste tires from the generators property is generallyperformed by a tire jockey or solid waste hau ler. Some hauling is done by tire users,tire dealers, or retreaders, but the majority of the over 193 million tires that go todum ps or stockpiles go by way of a hau ler who is paid to remove waste tires fromthe d ealers property. The hau ler m ay be held accountable for the n um ber of tires

and how they were disposed of, dep ending on the state. Hau lers may be p aid $0.35to $5.00 per tire to d ispose of the tires. If they th en d ispose of the tires legally, theymust pay a fee at a land fill or processing facility. If they stockpile the tires or illegallydump them, the tires create serious health hazards.

Whole Tire Disposal

There are no known whole tire disposal methods without adverse effects.Disposing of the tires above ground creates the hazards of mosquitoes and fires. Thealternate d isposal method is land filling or bur ial, which is also not w ithout

problems. In landfills, tires require a large volume because about 75 percent of thespace a tire occupies is void. This void space provides p otential sites for gascollection or the harboring of rodents. Some land fill operators report that tires tendto float or rise in a landfill and come to the surface, piercing the landfill cover.

The primary advantage to whole tire disposal is that processing costs areavoided. However, landfills bad experience with whole scrap tires has led toextremely high tipping fees or total bans on whole tires. Landfill fees for smallquantities range from $2.00 per passenger tirequantities, tipp ing fees range from $35.00 pertires, dep end ing on the region of the country.the fee for mixed municipal solid waste.

Shredded Tire D isposal

to $5.00 per tru ck tire. For m asston to over $100 per ton for wholeThese fees are generally at least twice

Shredding or splitting of tires is becoming increasingly common as part of thedisposal process. Shredded tires stored above groun d pose less of a hazard than dowhole tires. Shredding eliminates the buoyancy problem and makes tires into amaterial that can be easily landfilled. Shredding can reduce a tires volume up to 75percent. This volume reduction can also reduce transportation costs 30 to 60 percentsimply because fewer trips are required and maximum hauling weights may be

achieved more easily.

Hau l costs depend on m any factors, includ ing truck size, d istance hauled,local labor rates, etc. For semi-tru ck loads of 1,000 whole au to tires hauled over 100miles, typical costs are in the 15 to 20 cents per ton-mile range. This is equivalent to15 to 20 cents per 100 tires per mile. Shredding can reduce this cost by 30 to 60percent.

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The main disadvantage of shredding before landfilling is that an extraprocessing step is required, which adds costs. Shredder companies charge from $19to $75 per ton to shred scrap tires (8). T. Y. R. E. S., Inc. of the Los Angeles area iscurrently shredding for $18.50 a ton . But they say these costs will soon increasesignificantly because of labor and liability insurance that is requ ired by the city. Theysaid that about 20 tons per hou r need to be processed to make the shreddingprofitable. They have a m obile operation and mu st transport th e machine fromland fill to land fill (9). Satu rn Shred ders, maker of mobile shred d ing equ ipm ent, hasbroken down typical costs of a 500 to 800 tires per hour shredding operation. Theseare the cost per tire to the shredder comp any and do n ot include an y profit or fees.The cost breakdown is outlined in Table 6. For the two processing rates, the cost pertire for coarse shredding (4- to 8-inch) ranges from 18 to 25 cents per tire, or 18 to 25dollars per ton, assum ing passenger tires at 20 pounds per tire.

Shred ding costs are fairly constant nationally except for labor an d fuel, whichmay change the total cost up or dow n 10 percent. When shredd ing costs are add edto solid waste d isposal fees, it reflects the cost of landfilling shredd ed waste tires. For

comparison, several examples of tipping fees for whole waste tires in massquantities were obtained representing the northeast, midwest, south , and w estregion. These values were not regional averages, but are though t to be values thatare representative of the areas.

Table 7 compares the cost of landfilling whole tires and shredded tires in theUnited States. Shown are estimates of the money saved or lost by shredding prior toIand filling. In th e nor theast reg ion of the Un ited States, w here land fill costs arehighest, $38.00 per ton can sometim es be saved by shred ding tires before landfillingthem. In other areas of the country, disposal costs may increase by as m uch as $3.00

per ton by shredding before landfilling. These cost estimates are generalizations,and each community w ould n eed to d etermine if shredd ing before landfilling iseconomical. It becomes apparent through these comparisons that as landfill space isused up, shredding will become more beneficial, not only in terms of reducinghazard s, but also in terms of saving money.

State Legislation Affecting Tire Disp osal

Scrap tire legislation is increasing rapidly at the state level. In 1990, twelvestates passed or finalized scrap tire laws, regulations, or amendments (12). Thirty-sixstates now have scrap tire laws or regu lations in effect, and all but 9 states regulate or

have bills proposed or in draft form to regulate tires. A summary of the states lawsin effect in January 1991 is provided in Table 8. The legislations contents aresummarized in Table 9.

Several states have considered or are considering legislation that would banall whole tires from landfills. Minnesota has already banned all tires from landfills.In some other states, landfills have such high tipping fees that whole tires are

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Table 6

ESTIMATED TIRE SHREDDING COSTSMobile Shredders

(In dollars and cents per tire)

800 500

Tires/hr(1) Tires/hr(1)CAPITAL COSTS

Shredder 155,000 155,000

Shredder Stand 48,000 48,000Diesel Generator 30,000 30,000Infeed Conveyor 15,200 15,200Discharge Conveyor 16,800 16,800

Total Capital Cost (2) 2 6 5 , 0 0 0 265,000

ANNUAL COSTS

Debt Financing (3) 43,128 43,128

Operating & MaintenanceLabor (3 at $1 0/hr) 62,400 62,400Maintenance& Supplies 8,100 5,063Cutter replacement and sharpening 54,800 33,800Electricity @ 8 cents/kw-hr 25,000 16,000Overhead, Administrative, insurance 30,000 30,000

Total O & M 180,300 147,263

Total Annual Cost 223,428 190,390

Tires Processed Per Year (25% downtime) 1,248,000 780,000

Shredding Cost (cents/tire) 17.9 24.4

(1) Capacity for passenger tires.(2) Tractor for moving from(3) Financing Assumptions:

10 percent Interest10year amortization

Source: Franklin Associates,

location to location not included.

Ltd; based on estimates supplied by Saturn Shredders.

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Table 7

COSTS OF LANDFILLING AUTOMOTIVE WASTE TIRES IN THE UNITED STATES

(In dollars per ton or cents per tire) 1/

Costs by RegionNortheast Midwest South West

ShreddedLandf i l l Fee 2/ 4 5 1 8 1 6 1 3Processing Cost 2 5 2 5 2 5 2 5

Total 70 43 41 38

WholeLandfill Fee 3/ 108 7 5 50 35Processing Cost 0 0 0 0

Total 108 7 5

Savings Realized 38 32by Shredding 4/

50 35

9 - 3

1/ Since automotive scrap tires weigh 20 pounds each onequivalent to cents per tire.

2/ Reference 10.3/ Reference 11.4/ Total costs of Landfilling whole tires - total costs of

average, dollars per ton is

Landfilling shredded tires.


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effectively banned. Florida and Oregon have required that the tires be reduced involume by methods such as slicing or shredding.

Anoth er land fill restriction method, in add ition to bann ing tires or requ iringshredding, is to require that tires be disposed of in tire monofills, either whole orshredded. This allows precautions to be taken that will keep the tires buried. It alsokeeps open the potential for mining the material for some useful purpose at a laterdate. Specific rules for tire d isposal in m onofills will be d rafted by Oh io in 1991,following the completion of a feasibility study that is examining the engineeringprop erties and leaching p otential of shredded tires.

UTILIZATION ALTERNATIVES

In this section, tire u tilization m ethod s are d escribed . These includ e therecycling of tires into w hole tire and processed tire p rod ucts. The recyclingdiscussion is followed by a discussion of tire utilization methods that capture theirenergy va lue. These are incineration an d p yrolysis.

App lications of Wh ole Waste Tires

Whole waste tires can be used for artificial reefs, breakwaters, erosion control,playground equipment, and highway crash barriers.

a) Artificial Reefs and Breakw aters. In the late 1970s, the Goodyear Tire andRubber Company researched a nu mber of u ses for w hole tires. Among these useswere artificial reefs and breakwaters. Goodyear billed these applications as beingmajor ou tlets for scrap tires. They claimed that by 1978 they h ad built some 2,000reefs. In Ft. Lauderdale, Florida alone they were said to have used 3 million tiresand were adding one million tires per year to that reef alone. Besides stimulating

the fishing indu stry it was believed that tires would later be mined for their rawmaterials. Since that time, enthusiasm for this use has waned and scrap tire reefs arenow only built in minimal num bers.

Breakwaters are barriers off shore that protect a harbor or shore from the fullimpact of the waves. Breakwaters using scrap tires have been tested by the U.S.Army Corps of Engineers and were found to be effective on small-scale waves. Itwas recognized at the ou tset that this application w ould n ever use a great num ber ofscrap tires, but tires perform well in applications where floats are needed. Scrap tiresfor breakwaters and floats are filled with material, usually foam, which displaces 200pound s of water and can be used to float a number of devices such as m arinas and

docks and serve as small breakwaters.

Topper Industries of Vancouver, Washington, has patented the concept of amaterial-filled floating tire. The concept employs scrap tires as a durable containerfor holding th e flotation m aterial together (13). Topp er Ind ustries is the on lyknown prod ucer of scrap tire flotation devices and that company estimates that they

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Draft Proposed Regs La wAlabamaA l a s k aArizonaArkansas

CaliforniaColoradoConnecticutDelawareFloridaGeorgiaHawaiiIdahoI l l ino isIndianaIowaKansasKentuckyLouisianaMaineMaryland

MassachusettsMichiganMinnesotaMississippiMissouri

Table 8SCRAP TIRE LEGISLATION STATUS

January, 1991

Draft Proposed Regs LawX Montana

NebraskaX Nevada

X New HampshireX

New JerseyX New MexicoX New York

North CarolinaX North Dakota

OhioOklahomaOregon

X PennsylvaniaX Rhode IslandX South CarolinaX South DakotaX TennesseeX TexasX UtahX Vermont

X X VirginiaX WashingtonX Wisconsin

X West VirginiaX Wyoming

Draft - draft being written/bill in discussionProp - proposed/introduced in 1990 legislatureRegs - regulated under specific provision of solid waste or other laws (e.g., automotive wastes)Law - scrap tire law passed

Source: Scrap Tire News, Vol. 5, No. 1, January 1991

XX

X

X

XX

XXX

XX

X

XXX

XX

XXX

XX


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use 30,000 to 50,000 tires per year. These tires are included in breakwaters, marinaand dock floats, buoys, and other flotation applications. Topper Industries, Inc.obtains its tires from junk d ealers within a 100-mile rad ius of Vancouver,Wash ington. They then sell the floats to a market covering p rimarily the westernhalf of the United States.

Costs for constructing flotation devices are determined on a dollar per poundbasis. Topper Industries claims a one-half to three-fourth cost savings by using scraptire floats over wood, wood-fill, or other alternatives. The tire floats cost approxi-mately $0.06 to $0.08 per pound, whereas the economically closest alternative, foam-filled plastic, costs $0.10 to $0.14 per p ound of flotation (14).

Breakwaters and flotation devices presently consume approximately 30,000 to50,000 tires per year. If tire floats were to acquire the major portion of the flotationmarket, it m ay be possible to increase the current tire consumption by a factor ofthree to four, which would still be less than 1 percent of the annual generation ofscrap tires in the United States.

Artificial reefs are constructed by sp litting tires like bagels leaving abou t sixinches attached an d then stacking th em in triangular fashion. Holes are d rilledthrough this stack and about 45 pou nd s per tire of concrete are poured in the holesto anchor the reef. The 1,800 pound 3-foot high reefs are then hauled by barge 4 to 12miles off the coast and du mp ed in 60 to 100 foot deep water. They then providehabitat for marine organisms and fish (14).

The largest operations of building artificial reefs from scrap tires are occurringin Cape May and Ocean Counties, New Jersey. These two counties consume about

120,000 tires per year in making reefs. Cape May County has a goal of using 100,000tires per year for reefs, by combining tires with concrete and placing them in theocean (15). This is the only disposal option for scrap tires within Ocean County. It islikely that reefs are being built in other states, particularly Florida, but quantities oftires used are small and on an irregular basis (15).

In Ocean an d Cap e May Coun ties, tires are brought in by ind ividu als orhau lers wishing to d ispose of the tires. The counties may have an influx of tireswh en area fire dep artments require that storage sites be abated. Ocean Coun tycharges one d ollar per tire to accept the tires, while Cape May County charges $25.25per ton (equivalent to 25 cents per tire).

While artificial reefs do not hold the p otential to solve the scrap tire problem,they do hav e the potential to consum e more than th ey consum e now. Curren tlythere are an estimated 120,000 to 150,000 tires used ann ually in constru cting reefs.The goal of Cape May and Ocean Counties is to constru ct reefs with abou t 200,000tires annu ally. Currently they are d oing about 60 percent of this. One estimate ofnational potential is between one and 1.5 million tires used yearly (16). This ismuch higher than current levels because only two counties are actively constructing

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reefs. But, it is low compared to scrap tires generated annually because artificial reefsare restricted to fairly calm sandy coastline, where reef development is needed.Much of the northwest coast has rough water and Oregon has even banned artificialreefs from their sea waters (17). Cape May and Ocean Coun ties do not foresee an endto their activities as long as the state fish and wildlife agency continues to providesites to place the reefs.

Costs for constructing reefs are about $3.50 per tire. This cost is somewhatoffset by charging $1 per tire in Ocean County to accept tires or $25.25 per ton toaccept tires in Cape May Cou nty. This comp ares to the average of $45.25 per ton toland fill the tires in the n ortheastern United States. Since hau lers in Cape MayCounty save money by taking tires to the reef builders, tire supply is not a problem.In Ocean County, costs are minimized by using prison labor for building reefs; and acounty ow ned barge takes the reefs to the du mp site (15).

b) Playgroun d Equipm ent. The only large producer of tire playgroundequipment is Tire Playground, Inc. in New Jersey. President William Weisz saysthat his comp any currently uses up to 4,500 truck tires per year, but has used up to7,500 per year in the past. In addition to this are th e small-scale local and backyardrecreational uses of tires. The tire consumption cannot be easily determined, but itis thought to be small comp ared to the scrap tire sup ply. The d emand for TirePlaygrounds products is declining as the east coast economy improves and schoolsand parks select wooden playground equipment. The material cost for the tireplaygrounds is one-fourth of the cost of alternative equipment (18).

Even if the market for tire playgrounds were developed completely, it wouldrequire less than a million tires per year, which is less than one-half percent of theannu al generation.

c) Erosion Con trol. The California Office of Transportation Research hasdesigned and tested several erosion control applications of scrap tires. Scrap tireswere banded together and partially or completely buried on unstable slopes in testsconducted between 1982 and 1986. They found that tires used with otherstabilization materials to reinforce an unstable highway shoulder or protect achannel slope remained stable and can provide economical and immediatesolutions. Construction costs were reduced from 50 to 75 percent of the lowest costalternatives such as rock, gabion (wire-mesh/ stone matting), or concrete protection.Information on the ap plications has been d istributed since 1988, but it is difficult todetermine the number of times these designs have been used. John Williams of the

California Transp ortation Laboratory believes it would be fair to say that fewer than10,000 tires are used annually for erosion control. He says it is difficult to estimatethe potential annu al consum ption by this method as tire designs are not alwaysappropriate and tires for this use may not be acceptable in h ighly visible areas (19).

d) High way Crash Barriers. The use of scrap tires as crash barriers was studiedin the late 1970s by the Texas Transportation Institute. They determined that stacked

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tires bound by a steel cable and enclosed with fiber glass would reduce or absorbimpact of automobiles traveling up to 71 miles per hou r.

Since that time, no widespread use of tires in this application has occurred.State transportation departments generally prefer sand-filled crash barriers becausethey have excellent absorption characteristics and are easier to erect and dismantle.

App lications of Processed Waste Tires

Tire processing includes punching, splitting, or cutting tires into products;processing tires into crum b ru bber for use in rubber or p lastic produ cts, railroadcrossings, rubber reclaim, or asphalt paving; and chopping tires into small pieces orchips for use as gravel or wood chip su bstitutes.

Various ru bber prod ucts can be man ufactured using ru bber from scrap tires toreplace some or all of the virgin ru bber or other m aterial in the p rod uct. Tires maybe either split, punched, or stamped to yield shapes suitable for fabrication, or thetires may be processed to crum b size to make new prod ucts, usually by m ixing withother m aterials.

In this section the primary focus is on reuse of the rubber from tires.However, the fabric and steel may also be recycled.

a) Splitting/Punchin g of Tires. Splitting involves the removal of the steelbead and then using a stamp or punch to achieve the desired shape. Splitterspurchase tires on the market either graded or ungraded. They are responsible fordisposal of the part of the tires that are left as w ell as the u nrecyclable tires, so they

generally buy only appropriate tires. For example, steel-belted radials createproblems for the splitters and are u sually not wanted.

Products from the splitting of tires include floor mats, belts, gaskets, shoesoles, dock bumpers, seals, muffler hangers, shims, washers, insulators, and fishingand farming equipment. The market for this type of product is very limited;however, one Massachusetts company reports they use 2,000 tires per day tomanufacture fishing equipment, such as net parts, rubber discs, rollers, chain covers,strips for traps, etc. Because this industry is so diversified and there are nopublished data, it is difficult to make good estimates of the nationwide usage of split

rubber products. Estimates made in 1987 indicate the U.S. market for these productsis about 2.5 to 3.0 million tires per year (20). In the absence of additional data, it isassumed that the markets in 1990 remained at the same level.

b) Manu facture of Crumb Rub ber from Scrap Tires. Crumb rubber is made byeither mechanical or cryogenic size reduction of tires. Because of the high cost ofcryogenic size reduction (at liquid nitrogen temperatures), mechanical sizeredu ction by chopping and grinding is used most often. Typically tires are shreddedto redu ce them to 3/ 4-inch chips. Then a magnetic separator and fiber separator

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remove all steel and p olyester fragmen ts. The rubber chips are then red uced to

pebbles by a cracker grinder or granu lator. A series of screening and regrind ing

operations achieves the desired crumb size, which may be 600 to 800 microns. Thisrubber m ay be used in ru bber or plastic prod ucts, or processed further into reclaimrubber or asphalt products. A significant portion of the crumb rubber marketdem and is met by buffings and p eels from retread shops.

Crumb rubber can be mixed with other materials to make new products,includ ing p lastic floor m ats and adh esives. It can also be mixed with asphalt as an

additive to make cement products.

1) Crumb Ru bb er in Rub ber and Plastic Products. Crumb rubber may beincorporated into rubber sheet and molded prod ucts such as floor m ats, vehiclemu d guard s, and carpet pad ding or into plastic prod ucts, includ ing plastic floor matsand adh esives. Additional uses that have contributed to the expansion of thismarket over the last three years are rubber play surfaces, tracks and athletic surfaces,and garbage cans. In 1987 about 2.3 million tires (1 percent) were u tilized in th is

mann er. 1990 estimates have risen to 8.6 million tires per year , or 3 percent of thescrap tires generated th at year.

2) Crumb Rubber in Railroad Crossings. OMNI Products, Inc., asubsidiary of Reidel Environmental Technologies, Inc., has a patented process forusing crumb rubber to make solid rubber railroad crossings (21). The molded panelsfit between the tracks and fasten to the ties. OMNI is operating in three locations:Portland, Oregon; Lancaster, Pennsylvania; and Annis, Texas. Currently onlybuffings from tire retreading operations are being used , but the comp any is testingthe use of crumb rubber that still contains the fiber.

Rubberized crossings compete with crossings m ade of asphalt and timbers.The installed cost of the OMNI product is about 35 percent higher than timber andabout 100 percent higher than asphalt. The manufacturer claims that the life cyclecost of rubberized crossings can be lower than competing materials because theyexpect their prod uct to last abou t 10 to 20 years comp ared to 3 to 4 years for asphalt,dep ending on the traffic.

In 1990 OMNI used at least 14 million pounds of crumb rubber for railroadcrossings. Another company, Park Rubber Company of Illinois, used less than 1

million p ound s of cru mb rubber for the sam e pu rpose. If 20 million p ound s wereused for rubber railroad crossings, this wou ld be equ ivalent in w eight to abou t amillion scrap autom otive tires. However, if only buffings are used, only about 10percent of each tire is used , and the tire disposal problem is not solved.

There is a potential for growth of the rubber railroad crossing market. Thereare 185,800 public railroad crossings an d at least as m any pr ivate ones in the U.S.Less than 2 percent have rubber crossings. A typical railroad crossing consumesabout 350 pounds of rubber per tr ack foot.

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3) Rub ber Reclaim. For the trad itional rubber reclaim, crum b ru bberis mixed with water, oil, and chemicals and heated under pressure, thus rupturingthe carbon-sulfur bonds that cross-link the molecular matrix. The resulting partiallydevu lcanized rubber maybe formed into slabs or bales and shipped to manu fac-turers w ho p rocess and vu lcanize it for use as an alternative to virgin rubber to usein tires or to make mats and other ru bber produ cts.

Reclaim rubber tends to lose its elastic properties during processing and,

therefore, is no longer extensively used in tires because of the flex needed. That is, itdoes not become like new rubber. How ever, some n ew tires routinely contain oneto 2 percent crumb rubber (5).

Because of the increased use of synthetic materials in making new tires afterWorld War II, the reclaim industry has dramatically decreased in size. DuringWorld War II, about 60 percent of the rubber in tires was reclaimed rubber. Each ofthe major tire manufacturers has discontinued operating reclaim plants in the last 8to 10 years, until now only about one to 2 percent of the raw material for tires isreclaim. There are currently only two companies that produce reclaim rubber, i.e.,

partially-devulcanized ru bber, from whole tires for use in tires and other ru bberproducts. These companies are Midwest Rubber Reclaiming Co. in East St. Louis,Illinois and Rouse Rubber, Inc., in Vicksburg, Mississippi (22),

In 1987, the equ ivalent of 3,4 million tires w ere consum ed for reclaim rubber,By 1989 this figure had declined to 2,9 million tires (23), The reclaim industrysproduction capacity is estimated to be between 100 and 144 million pounds per year,(5 to 7 million tires per year), indicating a capacity of utilization of about 40 to 60percent, du e to limited m arket dem and , The Departm ent of Comm erce is no longerup dating its reclaim rubber p rodu ction figures yearly, It is estimated that p rodu ctionremained 2,9 million tires or less in 1990,

A new reclaim producer, Rubber Research Elastomers (RRE) of Minneapolisdeclared bankrup tcy in Au gust, 1989 (24), RRE, under Chapter 11, is currentlyexploring options for restructuring its operations, Since RREs Tirecycle productshave generated considerable interest, the process is worth discussing,

In the Tirecycle p rocess, first d eveloped in 1982, finely grou nd scrap rubber istreated w ith a liquid polymer to form a reclaimed rubber p rodu ct, RRE literatureclaims su perior bonding p roperties and suggests use in tread rubber and otherproducts including washers, mats, car parts, and tiedowns. The Tirecycle product isclaimed to be useful with thermoplastics such as polypropylene, polyethylene, and

polystyrene, as well as polyvinyl chloride, polyesters, and urethanes.

The RRE facility in Babbitt, Minnesota, financed by St. Louis Cou nty and thestate, was envisioned to have a capacity to process three million tires per year, all ofMinnesotas scrap tires. Actual production never reached over 10 percent of thatvalue.

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A stu dy by the Un iversity of Minnesota completed May 19,1989 (25),conclud ed that there are ad equate rubber markets for Tirecycle produ cts, but that theTirecycle product performance and delivery often failed to live up to customersexpectations. The study also conclud ed that the operation needs a large infusion ofcash (over two million dollars) before reaching 60 percent of capacity and reachingbreakeven conditions under an optimistic scenario. As a resu lt of the Un iversity ofMinnesota study, St. Louis County an d the state decided not to continue fund ing the

RRE Tirecycle project.

4) Crum b Ru bb er Additives for Pavements.Crum b rubber can also becombined with asphalt for use as a paving material. There are two main types ofprocesses for doing this. Advantages claimed for both include increased durability,flexibility, and longevity, when compared with conventional asphalt pavements.One application, referred to as Rubber Modified Asphalt Concrete (RUMAC), or thedry process, involves the displacement of some of the aggregate in the asphaltmixture with the ground whole tires. For this app lication the tire crum bs or chipsmay still contain some of the reinforcing materials such as polyester, fiber glass, andsteel. PlusRide

TMis the comm ercial nam e by wh ich one kind of RUMAC is

marketed. The TAK system, a non-patented generic system being tested by the Stateof New York and oth ers, is another form. PlusRide

TMand the TAK system each

have a different size distribution of the rubber aggregate in th e asphalt m ixture.

The second application of crumb rubber in asphalt (also a patented process)involves the blending/ reactivating of a certain percentage of the asphalt cementwith a groun d rubber th at is free of other tire constituents such as p olyester,fiber glass, or steel. This ap plication is r eferred to as asph alt-rubber (A-R), theArizona process, or the wet process, While A-R typically uses only one-third of therubber per mile of pavement that RUMAC uses (assuming equal thicknesses ofmaterial), it has been tested at more locations of the United States over a longerperiod of time. In the following pages, the technologies and uses of RUMAC andA-R are described. This is followed by a brief summary of research on pavementscontaining rubber.

(a) Rub ber M odified Asph alt Concrete.The PlusRideTM

technology typ ically uses 3 percent by w eight (60 poun ds per ton of total mix) ofgranulated coarse and fine rubber particles to replace some of the aggregate in theasphalt m ixture (26). Wire and fabric must be removed from the tire crumb andthe maximum moisture content is 2 percent. The granulated rubber is graded tospecifications, and in the Plu sRide

TMsystem, the aggregate is gap grad ed to m ake

room for the rubbergranu lated ru bber is to be un iformly d ispersedgraded to specifications as through out the pav ing mixture. Thefollows:

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PercentSieve Size Passing by Weight

1/ 4 inch 100US. No. 4 76-100U.S. No. 10 28-42U.S. No. 20 16-42

TAK, the non-patented RUMAC system being tested by the New York StateDepartment of Transportation, uses a un iformly graded ru bber crum b, and thereforedoes not r equire gap grad ing of the aggregate. The New York DOT is testing thissystem in highway strips using 1, 2, and 3 percent rubber in total asphalt mix. Theresults will be compared with results from PlusRide

TMtest strip s. It is too early for

any test results, since the strips were laid in the fall of 1989 (27).

The asphalt binder used in both types of RUMAC is the same as that used inconventional asphalt. Therefore, conventional equ ipment is used for mixing th efinal product. A belt conveyor is used to feed the rubber into the mixer.

The formula for PlusRideTM

w as invented in Swed en in the late 1960s and w aspatented in the United States by the PaveTech Corporation located in Seattle,Washington u nd er the trade nam e PlusRide

TM. Marketing is done by several

companies across the country,

PlusRideTM

modified asphalt is currently being tested in highways, streets,bridges, and airports, PlusRide

TMand TAK use all the rubber in waste tires,

including the sidewall interliner and tread portions, recycling all but the steel andfabric, Chief advantages over conventional asphalt are claimed to be increased

flexibility and durability, wh ich m ake it attractive for rehabilitating road surfaceswith severe cracking.

(b) Asphalt-Rubber. Asphalt-rubber w as developed in the late1960s and has been used pr imarily in the City of Phoenix, Arizona (28). The asp halt-rubber p rocess involves the blending of presized granu lated rubber into standardasphalt heated to over 400 degrees Fahrenheit. Blending occurs for about 45minu tes. A-R is produced by on e of two procedu res. In the Ar izona Refineryprocedure, an oil extender is added to the asphalt before heating and add ing rubber,and in the McDonald p rocedure, kerosene is added to the hot blended m ixture.Either p rocedure is performed just before app lication at the job site, as A-R cannot be

stored for more than 3 days w ithout adjustment of the mix,

The composition of A-R is highly dependent on the needs of the project.Rubber content is generally 15 to 25 percent of the binder by w eight and the crum bsize used ranges from fine to coarse in six different sizes. The crumb used isprod uced by a crumb rubber comp any w hich separates the ferrous and fabric

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Table 10

ASPHALT-RUBBER APPLICATOR COM PANIES

International Surfacing Phoenix, Arizona

Cox Paving Company Blanco, TexasEagle Crest Construction Company Arlington, WashingtonManh ole Adjusting Contractors Monterey Park, CaliforniaAsphalt Rubber Systems Riverside, Rhode Island

Source: Asphalt Rubber Producers Group

The Asphalt Rubber Producers Group (ARPG), which promotes asphalt-rubber, suggests that the doubled life of A-R pavem ents p rovides two options fordepartments of transportation. In one case, an inexpensive application of A-R

applied to severely deteriorated pavements can extend that pavements life. Fornew pavements, they suggest a long-term cost benefit by performing m ore thantwice as long as a standard pavement even though its original cost was less thantwice as mu ch.

(c) Research an d D emon stration of RUMAC and Asph alt-Rubber. Procurem ent guidelines for the use of rubber in asphalt were proposed bythe U.S. EPA in 1986, bu t have been tabled since that time because m any statehighway departments felt that not enough research had been completed at that timeto justify p rom otion of this technology nationally through procurement guid elines.Questions still remain about the life expectancy, suitability in different climates, andrecyclability.

Research on RUMAC in the United States, beginning in 1981, has beenconducted by a number of institutions and states, including the University ofOregon, the University of Idaho, the California, Alaska, New York, and New JerseyDepartments of Transportation, and the Colorado Department of Highways. Testsare still un der w ay, although m ost test results to date indicate improved d urabilityand skid resistance and less cracking.

Because the initial cost of PlusRideTM

is higher th an conventional asphalt and

because of the long times requ ired for satisfactory testing, it is not being u sedrou tinely at this time. Since 1979, however, this material has been used in over 60test applications in the United States.

Asphalt-rubber has been tested in a t least 25 states over the last 2 decades. Ithas been used primarily as a maintenance tool to save existing distressed surfaces,and most recently as a preven tive maintenance tool. It is not being u sed rou tinelyin new construction.

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One of the concerns regarding both RUMAC and A-R highways is theirrecyclability. Old asphalt is typically heated and mixed with fresh material to createnew asphalt. There is concern that when the rubber modified asphalt is reheated, itmay catch fire or p roduce noxious sm oke. The ind ustry claims that this will notoccur, and that recycling of rubberized asphalt has been successfully done in Sweden.However, many state highway departments are not yet convinced.

In 1985 the New York State Department of Transportation indicated apossibility of health and environm ental problems in using ru bber in aspha lt. Theyfelt the presence of carbon black, carcinogens, and unhealthy fumes may causeproblems in u tilizing ru bber in asphalt (33). Since 1985, New York has had noevidence that rubber significantly increases the health problems of asphalt (27). TheCalifornia Department of Transportation, which has experience with both RUMACand A-R, ind icated they are not aware of any ad ditional health problems due to theaddition of rubber (34).

d) Markets and Life Cycle Cost of RUMAC and Asphalt-Rubb er.Asphalt-rubber is diversifying into new markets w ith the construction of

geomembranes for lining of evaporation tanks, hazardous waste storage sites, andponds. A-R provides impermeable linings which restrict the movement of thesubstances to be contained (33). Though the A-R applicators promote theseapplications, they realize they are only a small supplement to the pavementsmarket. The greatest potential for utilizing large quantities of asphalt-rubberremains in road , runw ay, and parking lot construction app lications.

Pavement applications for asphalt-rubber include:

Crack and joint sealantsSeal coatsInterlayersHot m ix binder in overlays.

Crack and joint sealants are applied only on cracks and joints. Seal coatsinclud e hot asphalt-rubber sprayed on the surface followed by p recoated aggregate.Interlayers are the application of seal coats followed by either a standard overlay oran asphaltic-rubber overlay. Asphalt-rubber, when blended with an aggregate hotmix at about 9 to 10 percent by weight, serves as a binder in the thin overlay appliedto the road surface. The hot mix binder holds the greatest potential for using largequantities of scrap rubber because of the thickness and quantity of the overlay.

Fifteen to 25 percent of the binder is crumb rubber. Current investment andresearch projects are concentrated in th is use of asphalt-rubber (29).

A general rule in comparing costs of standard asphalt and A-R or RUMAC isthat the rubberized material will be between 40 and 100 percent higher than the costof standard asphalt. The lack of an exact cost ratio between the alterna tives is causedby the variability in the cost determining factors that are involved. In a California

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stud y in 1988, stand ard dense graded asphalt concrete controls cost app roximately$3.04 per square yard , while equal th icknesses of asphalt-rubber and RUMACapplications averaged about $6.13 per square yard (36). Table 11 compares costestimates from five areas, including New York, California, Washington, Phoenix,and Wisconsin.

Only Wisconsin has had negative results with regard to service life of asphalt-rubber. Wisconsin tried rubber mixed with recycled asphalt and got 10 times morecracking than with recycled asphalt alone. They now have 3 new A-R projectsplanned for 1990, using new asphalt. ARPG defends pavement life increases of twoand one-half to three times greater than conventional. Stand ard pavementsconsistently last 10 to 12 years, whereas asphalt-rubber pavements last 20 or moreyears. The ARPG claims that if an asphalt-rubber pavement were designed to lastthe same length of time as a standard pavement by making the layer thinner, thecosts will be the sam e.

The increased pavement life can be attributed to higher viscosity and

impermeability of rubberized asphalt. These properties have decreased thermalcracking, potholing, deformation, and reflective cracking in most states in whichtests were performed . Stud ies by the Alaska Department of Transportation show eddecreased stop ping d istances as a result of rubberized asphalt being more flexible andpreventing ice formation (37).

c) Lightw eight Road Construction Material. Since 1986, the State ofMinnesota has been using chipped tires as a lightweight fill material where roa

old report by us env tires

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