Abstract: In this work, an experimental investigation on the effectiveness of using soil-tire chip mixture as backfill for geosynthetic reinforced walls has been carried out. Earlier studies have established that sand-tire chip mixture has more shear strength than sand only backfill .In this study sand –tire chip mixtures containing 10%,20%and 30% tire chips were used as samples for Direct Shear test. Results revealed that adding tire chip increases the shear strength and maximum shear strength was obtained for 30% tire chip content. Higher shear strength and lower unit weight of sand-tire chip mixture make it effective for use as backfill material for various earth works. To study the effect of using this mixture in geosynthetic reinforced walls pull-out tests were carried out with a woven and non –woven PET geotextile. Test results shows that pull out force and Interaction coefficient increases with increasing tire chip content up to 30%.Further calculations were done to determine the number of geosynthetics and its embedded length required for retaining walls of different height. Both shows that walls using sand– 30%tire chip mixture backfill require less number and length of geosynthetic reinforcement than sand backfill. Lesser Rankine’s lateral earth pressure force considerably increases the wall stability. These advantages make sand –tire chip mixture an efficient backfill material by considerably reducing the overall cost of retaining wall construction. This also opens an effective solution for disposal and reuse of scrap rubber tires which is accumulating in a huge quantity day by day.
Keywords: Shear strength, Geosynthtic reinforced walls, Direct Shear test , Geotextile, Pull-out force.