and into a separate pile (see figure 1). This metal wire has not found much use in
industry in the United States as it contains too much rubber to be processed for scrap
metal as it is. As a result, there are stockpiles of this metal wire in the United States
(see Appendix D).
Figure 3 - Whole tyre shredding teeth on the left, and the rotating magnetic drum for separation of metal wires on the right.
Once most of the metal wire is removed from the rubber the shreds become
much more useful. Shredded rubber from tyres has found uses ranging from plant
mulch to highway bedding. In the United States the most common use for tyres is for
fuel; tyre rubber has a fuel value about equal to that of coal, although some sources
claim a greater fuel value (Farrell, 1999b). Although the process is not an
environmentally friendly recycling method, the waste from the burnt tyres, which
includes steel slag from the belts, can be used in creating concrete (Clark, Meardon, &
The civil engineering applications for tyre shreds are numerous. The chips can
be used as a highway bedding (Hylands & Shulman, 2003), insulation material, sound
barrier, and as a “sorptive” (a process that can filter some heavy metals) drainage
layer (Edil, Park, & Kim, 2004) to name a few such applications. The use of the tyre