<p><p><div><h2>Project Summary/Scope:</h2>The project involved incorporating shredded tires in highway embankments. Locally available Waste Tire (WT) chips and soils were used in different combinations in the test embankment. Embankment material varied from pure WT chips, chips mixed with soil, and WT chips layered with soils. Geotextiles were placed on all sides of the WT chips to serve as a separator between embankment fill and surrounding materials.</p><p>The thickness of cover soil over the fill layer varied to evaluate the effects of different cover soil depth on the performances. In addition, the possibilities of layered WT chip fill construction were also evaluated to determine the best embankment configuration. Sand or clay can be used in WT chip mixes although mixing of clay and WT chips in the field may prove difficult. Sand mixtures exhibit higher moduli than clay mixtures at the same soil-chip ratio.</p><p>The governing parameter in designing WT chip fill is the compressibility. A minimum soil cover layer of 3 feet overlying WT chips should be considered. Geotextiles are used to separate the cover soil from the porous chip fill to prevent migration of the soil into the chip matrix that could cause localized depressions. The handling and placement of tire chips were not a problem. A backhoe was found appropriate for spreading the chips evenly. Neither vibratory nor static compaction significantly induced compaction in the tire chips. Non-vibratory compaction was found to be more appropriate.<br><h2>Performance Monitoring:</h2>A two-year monitoring and evaluations of the embankment performance revealed that after an initial adjustment period (approximately 60 days) for settlement, the overall road performance was similar to most gravel roads. The WT chip-soil mixture performed similarly to the pure chips with a thicker soil cap. The presence of a thick soil cap reportedly helps reduce plastic deformation; comparatively, the layered section was not easily compacted and performed the worst.</p><p>Compaction control should not be based on final unit weight. Instead, an optimum number of coverage passes should be obtained based on a test section in the field. Vibratory compaction is not recommended because of the pressure-dampen behavior of WT chips.<br><h2>Project Technical Paper:</h2>Costentino, P.J., Kalajian, E.H., Shieh, C-S., and Heck, H.H., (1995), Developing specifications for waste glass, Municipal waste combustor ash and waste tires as highway fill materials, Florida Department of Transportation, FL/DOT/RMC/06650- 7754.<br><h2>Date Case History Prepared:</h2>November 2012</p><p></div></p></p>