Lakin Corp

The Leader in Tire Recycling Since 1919

Glossary of common recycling industry terms

Lakin and the Tire and Rubber Recycling Advisory Council (TRRAC) are pleased to present this handy reference guide to key terms in the tire and recycling industry.

This glossary was compiled from sources within the industry and is considered accurate, dependable and reliable.

BTU comparison of fuels Cross section of a standard tire Basic tire construction Tire performance by axis Tire lacing is a method of storing and transporting tires

Glossary

Terms commonly used in the recycling industry

 

Abatement: Removal of scrap tires from stockpiles or other sites which have accumulations of whole or size-reduced scrap tires.

Ambient Ground Rubber: Scrap rubber processed at or above ordinary room temperature.

ARCO-ARM-R-SHIELD (Arizona Refining Process): An asphalt-rubber blend process developed in 1975. The blend is composed of approximately 20% rubber (of which 40% is devulcanized and 60% ground ambient vulcanized) and 80% AR-4000/8000 with 2-4% Witco extender oil. The granulated rubber has gradings in which 98% pass the No. 16 mesh and 8% pass the No. 100 mesh. Diluents are not used routinely.

Asphalt Rubber: Asphalt cement modified with crumb rubber modifier (CRM).

ASTM: American Society of Testing Materials

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Bagel Cut: Cutting a tire in half along its circumference.

Baling: A method of volume reduction whereby tires are compressed into a bundle and banded together.

Barrel Stack: A means of storage in which tires are stacked flat on top of each other in a vertical position.

Bead: That part of the tire that is shaped to fit the rim. Made of high tensile steel wires that are wrapped in woven fabric and held by the plies.

Bead-to-Bead Retreading: The process of buffing a casing to remove the original sidewall, shoulder and tread, and applying new materials over these surfaces.

Bias Belted Tire: A tire with a bias ply carcass and stiff reinforcing belts extending from shoulder-to-shoulder (usually about a 36-degree angle). See Diagram

BR: Butadiene Rubber

BTU: British Thermal Unit. Tires contain an energy value when used as fuel. This value is measured in BTU.

Buffing Rubber: High quality tire rubber which is a by-product from the conditioning of tire casings in preparation for retreading.

Butyl Rubber: A general purpose synthetic elastomer (rubber) produced by copolymerizing isobutylene with small amounts of isoprene. Butyl rubber has a high resistance to chemicals and low permeability to gases. Its permeability to air is 70% better than that of natural rubber and for this reason is superior for tire tubes and tubeless tire inner liners.

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Carbon Black: An amorphous form of carbon produced commercially by thermal or oxidative decomposition of hydrocarbons. It is used principally in rubber goods, pigments, and printer's ink. It is not an inert filler but enhances and reinforces various properties of rubber. It is a primary ingredient in the compounding of tires.

Casing: The whole tire generally in a worn state suitable for retreading.

Char: Residue remaining after pyrolysis of a tire and after removal of the inherent steel and fibers and other inert materials such as glass, dirt and rocks.

Chopped Tire: A tire cut into randomly sized pieces which have no uniformity.

Civil Engineering Applications: A form of reusing scrap tires, either whole or shredded, in place of naturally occuring materials in construction. Some examples are: as an aggregate replacement in leachate collection systems, lightweight fill material, crash barriers and reef construction.

Classifier: Any apparatus for separating mixtures of materials into their constituents according to size and density.

Collection: The act of picking up and moving take-off tires from th location of their generation to sorting stations or recycling facilities.

Collection Fee: Fee charged to collect and/or haul and/or transport and/or sort take-off tires or shredded tire material.

Commodity: A commercial material such as ground rubber.

Cracker Mill: A machine that tears apart scrap tire rubber by passing the material between rotating corrugated steel drums, reducing the rubber to various sizes.

Crumb Rubber: Material derived by reducing scrap tire or other rubber into uniform granules with the inherent reinforcing materials such as steel and fiber removed along with any other type of inert contaminants such as dust, glass or rocks.

Crumb Rubber Modifier (CRM): A general term for scrap tire rubber that is reduced in size and used as a modifier for asphalt paving materials.

Cryogenically Ground Rubber: Rubber that results from the process of freezing scrap tire or other rubber and crushing the rubber to the particle size desired.

Cryogenics: A technology for processing materials at very low temperatures. In processing rubber, liquid nitrogen or commercial refrigeration methods are commonly used to embritle rubber. The embrittled rubber is then processed in a hammermill or granulator to a desired product size.

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Depolymerization: A process that reduces a polymer to individual elements. For rubber, this reduction permits the blending of these individual elements with other polymers.

Devulcanization: A process in which crumb rubber is subjected to treatment by heat, pressure or the addition of softening agents to regenerate the rubber compound to its original plastic state.

Dry Process: Any method that mixes crumb rubber modifier with aggregate before the mixture is charged with asphalt binder. This method applies only to hot-mix asphalt production.

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End Market: An entity that receives processed or unprocessed tire recyclable material and uses it as a finished product or as raw material for a manufacturing process.

Energy Recovery: The extraction of the fuel or heat value from whole or processed tires through incineration.

EPDM: Ethylene Propylene Rubber

Extruder: A machine for forcing material through a confined opening or die to produce a desired shape in any length.

Extrusion: A process of mechanically forcing material (such as blended crumb rubber) through a confined opening to produce film, strip, tubing or other shapes.

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Fines: Rubber material that passes through a standard size screen on which coarser fragments are retained.

Flow Control: A legal or economic means that directs the movement of materials to a specific destination.

Fluff: The textile or reinforcing materials liberated from scrap tires or other rubber reinforced products during processing for crumb rubber.

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Gasification: Any chemical or heat process used to convert rubber to a gas.

Generator: Any person or business entity who acquires worn or scrap tires through personal use or in the ordinary course of business.

Granulator: A machine that shears apart scrap tire rubber, cutting the rubber with revolving steel plates that pass at close tolerance, reducing the rubber to smaller sizes.

Ground Rubber: Material that results from processing scrap rubber through various mechanisms (e.g., crackermill, shredder, granulator).

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Hammermill: A machine that impacts materials against heavy metal hammers loosely pinned to a shaft which rotates at a high velocity to reduce scrap tire rubber particle size.

Hauler: Those persons, firms, corporations or governmental agencies responsible (under oral or written contract or otherwise) for the collection of take-off tires, whole scrap tires, or rubber materials within the geographic boundaries of the contract community(ies), and the transportation of such materials to sorting stations, recycling centers or end markets.

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Lacing Tires: A method of arranging tires to maximize the use of space. This method can be used to store tires indoors or outdoors or to transport tires. See Diagram

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Managed Tire Site: A tire pile or storage facility where the owner/operator stores or processes scrap tires in compliance with the appropriate regulations.

McDonald or Arizona Technology: The preparation of asphalt rubber blends using coarse ground rubber.

Mesh: A term commonly used to describe or measure the size of crumb rubber. Crumb rubber is sized by the screen through which it passes in the production process. The finer the screen, the more openings it will have per linear inch, i.e., 30 mesh means there are 30 holes or openings per linear inch. The greater number of openings, the smaller the material must be to pass through the screen.

Micro Mill: A machine that further reduces crumb rubber to a very fine particle, at ambient temperatures, using rotating abrasive discs or other abrasives.

Monofill: A single use landfill or landfill cell used for homogeneous material storage.

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Nominal Size: A term used to describe size for purposes of general identification; the actual size of a part will be approximately the same as the nominal size, but need not be exactly the same.

NR: Natural Rubber

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Particulate Rubber: Raw, uncured, compounded or vulcanized rubber that has been transformed by means of a mechanical size reduction process into a collection of particles, with or without a coating of a partitioning agent to prevent agglomeration during production, transportation or storage.

PLUSRIDE: A patented form of rubber modified asphaltic mix. The product was developed in 1960 in Sweden and patented under the name PlusRide in the United States and Rubit in Sweden. It uses coarse rubber particles (6mm to 0.6mm -or- 1/4" to 1/16") as rubber-filled aggregates, generally about 3% weight of mix. The rubber is added directly to a gap-graded aggregate so that a relatively dense grading between the aggregate and rubber is obtained.

Post Consumer Scrap: Scrap materials, normally source-separated, that no longer have value for which they were originally intended, but can have potential reuse value as a raw material in new product applications.

Powdered Rubber: Rubber comprised of finely dispersed particles, less than 40 mesh (425 microns) in size, that are generally characterized as light, dry and having very high surface areas. ASTM D11 defines powdered rubber as being composed mainly of non-spherical particles that have a maximum particle dimension equal of below 40 mesh (425 microns).

PTE (Passenger Tire Equivalent): A conversion measurement where five passenger tires at 20 pounds each is equivalent to one truck tire at 100 pounds.

Pulverized Rubber: Material that has been crushed, pounded or ground to smaller particles.

Pyrolysis: The thermal decomposition of rubber in the absence of oxygen to chemically break the tire into its original components of oil, gas and char.

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Radial Tire: A tire construction in which the body ply cords are placed straight across the tire from bead to bead; the belt plies run nearly circumferentially around the tire, under the tread, and constrict the radial ply cords. See Diagram

Reclaim or Reclaimed Rubber: The product resulting from treatment of ground vulcanized scrap rubber tires, tubes and miscellaneous scrap rubber by the application of heat and chemical agents, followed by intense mechanical working. A substantial "devulcanization" or regeneration of the rubber to its original state is achieved, thus permitting the material to be compounded, processed and revulcanized.

Recycled Rubber: Any rubber material derived from processing scrap tires or other rubber products.

Remanufactured Tire: A tire produced from a worn tire. The process involves inspecting, repairing (if necessary) and buffing the sidewall, shoulder and tread areas to permit the application of new rubber to these areas.

Repaired Tire: Any tire with punctures, cuts or other types of injuries that have been reconditioned to restore strength and flexibility for additional vehicle service.

Resource Recovery: A general term used to describe the extraction of usable materials or energy from discarded products. Methods include:

  • Conversion: Mainly energy recovery by using scrap material for heat and fuel values (e.g., TDF)
  • Transformation: Chemical processes which create new by-products (e.g., surface treated ground rubber)
  • Reuse: The recovery or reapplication of a tire in a manner that retains its original form or identity (e.g., used tire, retread)
  • Recycling: The series of activities by which take-off tires are collected, sorted, processed and converted into raw materials and used in the production of new products (e.g., rubberized asphalt)

Retreadability: Ability of the tire casing to be retreaded and provide acceptable performance.

Retreaded Tire: A casing to which a new tread has been affixed to extend the usable life of the tire.

Rubber Modified Asphalt: A general term used to identify the incorporation of scrap tire rubber into asphalt paving materials.

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SBR: Styrene-butadiene Rubber

Scrap Tire: A tire which can no longer be used for its original purpose, due to wear or damage, but can be recovered whole or in part through reuse, recycling, conversion or transformation.

Screen: A large sieve of suitably mounted wire cloth, grate bars or perforated sheet iron used to separate materials by size.

Shear Shredder: A type of shredder which has two counter-rotating shafts fitted with cutting discs or knives with hooks and spacers that intermesh and overlap.

SHRP (Strategic Highway Research Program): In 1987, the SHRP began developing a new system for specifying asphalt materials. The final product of the SHRP asphalt research program is a new system referred to as Superpave, which stands for Superior Performing Asphalt Pavements.

Sieving: A process for classifying rubber particles. Gradations are usually expressed in terms of total percent passing or retained. The percent passing indicates the total percent of rubber that will pass each given sieve size. The total percent retained is the opposite of percent passing or the total percent passing each given sieve.

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Take-Off Tire: A tire which has been removed from a vehicle and retained for reuse or recycling by qualified tire processors.

Tipping Fee: A fee charged by the operator of a tire processing, recycling, energy recovery or disposal facility to accept scrap tires - either whole or shredded - delivered to these locations.

Tire Composition: This may be defined as follows: a new, original equipment (OE) passenger tire weighs an average of 19 pounds and a new OE truck/bus tire weighs 130 pounds. The weight percent of the respective tire components can be broken down for average passenger and truck/bus OE tires as follows:

  • Material Passenger Truck/Bus
  • Polymer: 44%   43%
  • Additives: 42%   37%
  • Bead Wire: 3%   1%
  • Steel Cord: 8%   13%
  • Bead Wire 3%   6%
  • Av. Tread Wt. 32%   25%

Tire Derived Fuel (TDF): A fuel derived from scrap tires of all kinds. This may include whole tires or tires processed into uniform, flowable pieces which satisfy the specifications of the end-user for fuel. See Diagram

Tire Derived Material (TDM): Any rubber, steel or fabric material derived from processing tires or rubber products. These materials are found in a variety of sizes, shapes and forms.

Tire Recycling: Any process by which scrap tires or scrap tire derived materials are converted into products or raw materials.

Tire Shredder: A mechanical device used to reduce tire materials into smaller pieces. The pieces are usually irregularly shaped.

Tire Shred: A term used to define randomly ripped, torn or cut tire pieces which have no uniformity.

Tread Peels: Strips of tire tread rubber or "peelings" which are removed during processing.

Trommel: A revolving cylindrical screen used for separating mixtures or materials into their constituents according to size and density. Also referred to as a trommel screen.

Transporter: A person or entity responsible for the transport of take-off tires, scrap tires or tire material.

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Used Passenger Tire: A take-off tire that retains a minimum 3/32 inch tread depth in its most worn groove and can be safely returned to its original purpose after inspection or proper repair.

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Waste Tire: A tire that is permanently disposed rather than recycled, reused or burned for its energy value.

Wet Process: Any method that blends crumb rubber modifier with an asphalt cement before incorporating the binder.

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