Page 189 - Materials Chemistry, Second Edition

CAT3525_C06.qxd 1/29/2005 9:56 AM Page 160
160 Waste Management Practices: Municipal, Hazardous, and Industrial

TABLE 6.11
Composition (by wt) of Passenger and Truck Tires

Material Passenger Tire (%) Truck Tire (%)
Natural rubber 14 27
Synthetic rubber 27 14
Carbon black 28 28
Steel 14–15 14–15
Fabric, fillers, accelerators, antiozonants, etc. 16–17 16–17
Average weight (lb)
New 25 120
Scrap 20 100
Source: Rubber Manufacturers Association, no date. Reproduced with kind permission of the Rubber Manufacturers
Association.

10 33.5
Reuse Vehicles Retread
10 33.5
242 (100 %)

42.2 (17.4%) Waste tire inventory 12.5 (5.0%) Used
export
187.8 (77.6%)

Illegal dumping Landfill Stockpile
1. Whole
2. Shredded

25.9 (10.7%) 0.3 (0.1%) 16.0 (6.6%)
Combustion Whole tire applications Processed tire products
1. Power plants 1. Reefs and 1. Processed rubber
2. Tire plants breakwaters products
3. Cement plants 2. Playground 2. Crumb rubber for
4. Pulp and paper mills equipment pavements
5. Small package 3. Erosion control 3. Playground gravel
boilers 4. High crash barriers substitute
4. Sludge composting
5. Split tire products
FIGURE 6.18 Destinations for scrap tires (U.S. EPA, 1991).

6.14.3 RECYCLING
Over the past decades many innovative uses have been found for recycled tires. For example,
ground rubber from scrap tires is recycled into rubber products such as rubber-modified asphalt,
playground cover, and flooring material. Tire material has also been employed as an alternative to
pea stone in septic systems. Some facilities use scrap tires as a combustion fuel.