Millions of scrap tires are discarded annually in the United States, the bulk of which are currently landfilled or stockpiled. This consumes valuable landfill space, or, if improperly disposed, creates a fire hazard and provides a prolific breeding ground for rats and mosquitoes. The use of tire shreds as lightweight fill material can sharply reduce the tire disposal problem. The present study, based on laboratory testing and numerical modeling examines the feasibility of incorporating tire shreds and rubber-sand mixtures as lightweight geomaterial in embankments and backfills. The growing interest in utilizing waste materials in civil engineering applications has opened the possibility of using reinforced soil structures wit non-conventional backfills. The laboratory testing program of the present study includes the determination of volumetric behavior of rubber-sand mixtures with geogrids and geotextiles through pull-out and direct shear tests. The test results have been used to perform numerical modeling of tire shred and rubber-sand backfills in walls. It has been found that the use of tire shreds and rubber-sand (with a tire shred to mix ratio about 40%) in highway construction offers technical, economic, and environmental benefits. The salient benefits of using tire shreds and rubber-sand include reduced weight of fill, adequate stability, low settlements, good drainage (avoiding the development of pore water pressure during loading), separation of underlying weak or problem soils from subbase or base materials conservation of energy and natural resources, and usage of large quantities of local waste tires, which would have a positive impact on the environment.
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