Applications of Whole Waste Tires
The unique properties of waste tires have made the elimination of waste
tire stockpiles difficult. Several of these problems are associated with
their toughness (difficult to break down and decompose), durability (difficult
to process), shape (large void space, poor space efficiency for storage
and transportation) and volume (occupies a large volume).
On the other hand, once a suitable usage (second life) is identified
for waste tires, few materials can match their properties to the same level
including, durability and toughness. A main focus of application of whole
waste tires is to utilize these unique properties and characteristics.
Today, many of the applications are in civil engineering related fields.
Whole waste tires have found demand, suitability and economic advantages
in fields such as erosion control, highway crash barriers, breakwaters,
dams, artificial reefs, playground equipment, etc. The main technological
challenge resides in optimization of merits and identifying new areas for
applications.
In 1998, the total number of waste tires used in these applications
was less than 10 % of the total number discarded annually. This number
represents an increase of more than 100 % over the previous 8 years.
Examples of Applications:
Erosion Control:
Several research groups have reported on the design and testing of
erosion control applications of waste tires.
Scrap tires were banded together and partially or completely buried
on unstable slopes. These reports have stated that tires used with other
stabilization materials to reinforce unstable slopes remained stable and
provided economical and effective solutions. Construction costs may be
reduced by 50 to 75 % of the lowest cost alternative such as rock, wire-mesh/stone
matting, or concrete protection1)2).
Dams:
Tire dams may be more suitable for rapid-flowing streams compared to
conventional dams. Conventional dams are made of sand and gravel and are
easily washed out by streams. Concrete dams are costly and require skilled
personnel to build.
Tires possess sufficient strength as a dam construction material. They
catch and hold sediments effectively. Moreover, the construction procedure
does not require highly-skilled personnel.
From a waste tire management point of view, dam construction could
utilize a large number of tires compared to other applications3).
Playground Equipment:
Today, many schools and parks prefer wooden playground equipment. However,
the cost for tire playground equipment is approximately 25 % of the cost
of other alternatives4).
Export
(Not counted as a recycling in this report):
In 1998, 15 million waste tires were exported.
Demand for used tires exists outside of the U.S. (and even within the
U.S.). Used tires are sold as cheaper replacement tires. Export effectively
extends tire life, like retreading. However, many researchers have argued
that this should not be counted as recycling since the tires ultimately
need to be discarded. If tires are exported from a country having relatively
strict environmental regulations to a country not having any particular
regulations, discarded or stockpiled tires would certainly cause similar
environmental problems as mentioned previously.
The transportation of waste tires might introduce non-native small
animals or insects to a new location causing an adverse impact to the local
environment.
References