Physical and chemical properties of recycled tire shreds for use in construction

The purpose of this study was to determine the physical and chemical properties of tire shreds for use in engineering construction as a replacement for aggregates in embankments or as backfill. In general, test results revealed that tire shreds can be utilized in construction applications. As the size of tire shreds increases, physical properties such as specific gravity remained constant at 1.06- 1.1. Gradation of tire shreds was also tested, and the results were comparable to other researchers (i.e., ranging from 50 to 300 mm). As the tire shred size increased, the hydraulic conductivity increased from 0.2 to 0.85 cm/s. Increasing the compaction energy had little 2 effect on the final compaction density. The angle of friction and cohesion ranged from 15 to 32degrees and 349 to 394 N/m(2), respectively. As the particle size (from 50 to 300 mm) of the tire shreds increased, the shear strength of the scrap tire increased. Moreover, as the tire shred size increased, compressibility increased. Chemical analysis of tire shreds was conducted to illustrate how properties such as total organic carbon (TOC), pH, and turbidity change with tire size. As tire shred size increases, the results illustrated a decrease in TOC (from 22.7 to 3.1 ppm) and turbidity (from 254 to 99 NTU). Continuous flow column tests were conducted on tire shreds and showed improved water quality (TOC, turbidity, and iron) with time. However, pause flow column tests showed reduced water quality, which implies that placement of a tire embankment below the water table where ponding can occur may reduced water quality. TGA tests were also conducted to determine the thermal stability of tire shreds. In general, tire shreds are stable up to temperatures of 200degreesC. This indicates that other mechanisms may be attributed to the exothermic reactions, which occurred in tire fills.