Asphalt-Rubber Concrete implies the use of an
asphalt-rubber binder with gap or open graded aggregate
gradations in a hot mix application.
Automobile
Tires tires with an outside diameter less than 66 cm (26 inches) used on
automobiles, pickups, and light trucks.
Buffing
Waste high quality scrap tire rubber which is a byproduct from the
conditioning of tire carcasses (casings) in preparation for re-treading.
Crackermill
machinery that tears apart scrap tire shreds by passing the material
between rotating corrugated steel drums, reducing the size of the rubber to
a crumb particle generally 4.75 mm to 425 microns (No. 4 to No. 40) mesh
sieve.
Crumb
Rubber Modifier (CRM) a general term for scrap tire rubber that is reduced
in size and used as a modifier in asphalt paving materials.
Cryogenically Ground Rubber a process that freezes the scrap tire rubber
and crushes the rubber to the particle size desired.
Devulcanized Rubber rubber that is a complex macro structure material ant
through vulcanization the sulfur molecules form complex cross linkages
between and within the rubber macromolecular structure.
Devulcanization is
the process by which the sulfur molecules are de-linked from the rubber
molecules and stabilized, thereby facilitating the formation of new
cross-linking structures with reapplication of heat and pressure.
Dry Process
any method that mixes the crumb rubber modifier (CRM) with the aggregate
material before this mixture is charged with the asphalt cement. This method
only applies to hot-mix asphalt production.
Extender
Oil an aromatic oil used to supplement the reaction of the asphalt cement
and the crumb rubber modifier (CRM).
Granulated
Crumb Rubber Modifier (CRM) cubical, uniformly shaped, cut crumb rubber
particles with a low surface area, which is generally produced by a
granulator.
Granulator
a process that shears apart the scrap tire rubber, cutting the rubber with
revolving steel plates that pass at a close tolerance, reducing the rubber
to particles generally 9.5 to 2.0 mm (3/8 inch to No. 10) sieve size.
Ground
Crumb Rubber Modifier (CRM) irregularly shaped, torn crumb rubber
particles with a large surface area, generally produced by a crackermill.
Reaction
the interaction between asphalt cement and crumb rubber modifier (CRM) when
blended together at a certain temperature for a certain period of time. The
reaction, more appropriately defined as polymer swell, is not a chemical
reaction. It is the absorption of aromatic oils from the asphalt cement into
the polymer chains of the crumb rubber.
Recycled
Tire Rubber rubber obtained by processing used automobile, truck or bus
tires.
Rubber Aggregate crumb rubber modifier (CRM) added to the hot asphalt
mixture using the dry process.
Rubber-Modified Asphalt Concrete a hot mix asphalt concrete mixture with
dense graded aggregates a rubberized asphalt type of binder. (Note: The CRM
percentage is generally low (5 to 10%) and is generally finer mesh (30 mesh
or lower).
Rubber-Modified Hot-Mix Asphalt a hot-mix asphalt mixture that
incorporates the crumb rubber modifier (CRM) primarily as rubber aggregate.
Also known as the "dry process".
Rubberized
Asphalt asphalt cement modified with crumb rubber modifier (CRM) at less
that 15 percent by total weight of the asphalt cement.
SAM the
abbreviation for a Stress Absorbing Membrane. A SAM is used primarily to
mitigate reflective cracking of an existing distressed asphalt or rigid
pavement. It is usually associated with an asphalt-rubber binder sprayed on
an existing pavement surface at .60 gallons per square yard (±05 gallons per
square yard) and immediately followed by an application of a uniform
pre-coated aggregate, which is then rolled and the aggregate is embedded
into the binder layer. The nominal thickness normally ranges between 6 and 9
mm (1/4 and 3/8 inch).
SAMI the
abbreviation for a Stress Absorbing Membrane Interlayer. A SAMI is the same
as aSAM but is applied prior to an asphalt concrete overlay. This overlay
may or may not contain crumb rubber modifier (CRM).
Shredding
process that reduces scrap tires to small pieces 0.15 meter squared (6
inches squared) and smaller.
Stress
Absorbing Membrane a surface treatment (membrane) using an asphalt-rubber
spray application and cover aggregate. Same as a SAM.
Stress
Absorbing Membrane Interlayer a surface treatment (membrane) generally
associated with an asphalt-rubber spray application and cover aggregate,
designed to resist the stress and strain of reflective cracking and delay
the propagation of the cracks through a new overlay. Same as a SAMI.
Tread
Rubber rubber that consists primarily of tread rubber with less than 5
percent sidewall material (approximately).
Truck Tires
tires with an outside diameter greater that 66 cm (26 inches) and less
that 152 cm (60 inches); used on commercial trucks and buses.
Vulcanized
Rubber rubber that has gone through the vulcanization process. This is a
process by which an agent, such as sulfur, is added to rubber in the
manufacturing process to give the product certain required characteristics,
such as strength, hardness and elasticity. Rubber is a complex macro
molecular structured material and through vulcanization the sulfur molecules
form complex cross linkages between and within the rubber macromolecular
structure.
Wet Process
a method that blends crumb rubber modifier (CRM) with the asphalt cement
before incorporating the resulting binder for use in an asphalt paving or
surfacing project. This terminology is generally associated with
asphalt-rubber binder materials.
Whole Tire
Rubber rubber that includes tread and sidewalls in portions that
approximate the respective weights in an average tire.
