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:
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).
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).
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).
(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.
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