SAND REINFORCED WITH SHREDDED WASTE TIRES

The objective of this study was to investigate the feasibility of usin g shredded waste tires to reinforce sand. Direct shear tests were cond ucted on mixtures of dry sand and shredded waste tires. The following factors were studied to evaluate their influence on shear strength: no rmal stress, sand matrix unit weight, shred content, shred length, and shred orientation. From results of the tests, three significant facto rs affecting shear strength were identified: normal stress, shred cont ent, and sand matrix unit weight. A model for estimating the strength of reinforced soils was also evaluated to determine its applicability to mixtures of sand and tire shreds. When the model is calibrated usin g results from one shred content, it may be useful for estimating the friction angle for other shred contents. In all cases, adding shredded tires increased the shear strength of sand, with an apparent friction angle (phi') as large as 67 degrees being obtained. Shred content and sand matrix unit weight were the most significant characteristics of the mixes influencing shear strength. Increasing either of these varia bles resulted in an increase in phi'. Tests were also conducted on spe cimens consisting of only shredded tires (no sand), and the friction a ngle obtained was 30 degrees.