Engineering properties of tire/soil mixtures as a lightweight fill material
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The United States Environmental Protection Agency (USEPA) estimates that over 279 million discarded tires are being added annually to the already existing stockpile of two billion tires. Current disposal and stacking methods of waste tires are not acceptable due to the possibility of fire and health hazards. Several states and the federal government have issued legislation that encourages or mandates the recycling of discarded tires. One application where shredded tires can be used is as a lightweight fill material behind retaining walls or in highway embankments over weak or compressible soils. This paper presents the engineering properties of shredded tires, Ottawa sand, and a mixture of 50% Ottawa sand and 50% shredded tires by volume (70% Ottawa sand and 30% shredded tires by weight). The maximum size of the tire chips used was 4.75 mm. Gradation, specific gravity, void ratio, density, permeability, and consolidated-drained (CD) triaxial tests were performed as part of the testing program. Although the data obtained were limited to the above three mixes, the results indicate that the use of shredded tires/Ottawa sand mixes as a lightweight fill material is very promising. However, long-term impact of leachates from tires on groundwater quality should be investigated.