Urbanization and the Geoenvironment - Sustainable Practices in Geoenvironmental Engineering - page 239

TABLE 7.7
Applications o f Recycled Scrap Tires

Tire Form Application

Tire chips Embankments, aggregate materials retaining walls, bridge abutment backills

Reduction in frost penetration due to low thermal conductivity
Adsorption of organic chemicals in leachate collection systems, for gas migration control
trenches, gas collection and venting layer in caps, leachate recirculation trenches, drainage
layer in covers in landills
Low-height retaining structures

Whole tires Highway applications for stabilization of road shoulders or noise barriers

Rubber Rubberized asphalt concrete with long life and decreased thermal cracking

Crum rubber Rubber is molded to form panels for railway crossings that it between tracks instead of

timber crossings

Tire shreds VOC movement reduction in groundwater by addition to bentonite slurry walls

Ground tires Sorption of VOCs from wastewater in wastewater treatment plants

Source: Sharma, H.D. and Reddy, K.R.: Geoenvironmental Engineering . 2004. Copyright Wiley-VCH Verlag GmbH

& Co. KGaA. Reproduced with permission.

and the remaining was discarded (USEPA, 2009). The promotion of environmentally sound
waste disposal and treatment methods for construction debris constitutes one of the pro-
grams of the United Nations Agenda 21 (1993). Concrete can be recycled into aggregates
of concrete, base foundation, new pavement, road shoulders, or backill. Scrap wood can
be used for landscaping (wood chips, mulch, groundcover), wood-based geotextiles for
landills as fuel or in building products (iberboard products, rigid boards, plastic lum-
ber). Asbestos, lead-based paints, PCBs, and CCA and pentachlorophenol (PCP) leaching
from treated wood may be a concern. Cardboard, dry wall, rubble can be used as aggre-
gate. The publication WasteSpec (Triangle J Council of Governments, Research Triangle
Park, NC, 1995) provides speciications for waste reduction, material recovery, and reuse
and recycling of construction waste. WasteSpec includes waste reduction techniques dur-
ing construction, reusing waste material on site, salvaging waste material at the site for
reuse or resale, returning unused material for credit, and delivering waste material for
recycling.
Composting is one of the simplest of processes that can be used for treatment of organic
wastes. It can also be very sophisticated. At the present time, it is used mainly for food
wastes. However, composting materials can include garden and vegetable cuttings, paper
and cardboard, garbage, and any decomposable organic matter. It is applicable for home
owners, individual institutions, and even communities. It has increased in popular-
ity signiicantly due to consumer awareness in decreasing the amount of wastes going
to landills. Moisture and oxygen levels, pile temperature and odor must be monitored
throughout the process. Carbon to nitrogen ratios are the other important factors that must
be optimal to ensure the success of the process. Composted products can be used as soil
conditioners. The use of in vessel systems or bioilters with aerated piles will reduce odor
levels considerably.
Anaerobic digestion is the microbial stabilization of organic materials without oxygen
to produce methane, carbon dioxide, and other inorganic products. It is the most common
biological treatment method used for high-strength organics in the world. At present, the
technique is used for industrial, commercial, and municipal sludges (Mulligan, 2002). It