Laboratory investigating of mixed soil-shred tire behavior for application in railway track subgrade

One of the suggested applications for use of waste tire is mixing of this material with soils in shredded form for use in retaining walls backfill and embankments. In this regard, comprehensive studies have been accomplished in the field of road engineering but no research works could be found in the railway engineering. As one of the important parameters is railway embankment design is Ev2 (modulus of elasticity in the second loading cycle in PLT) so this research is devoted to investigating of physical and mechanical behavior of soil mixed with shred tire. For his purpose by using the GW-GC as a base material which can be used in railway embankment and subgrade, it is mixed with three different percent 5, 10 and 15 of shred tire with range of aggregation 0.475 to 2.5 centimeters. In continue a series of physical and mechanical tests are performed on base soil and soil mixed with shred tire including compaction, sand equivalent, CBR, direct shear test. In the last stage of the laboratory investigations four cyclic plate loading tests are performed in loading chamber box with dimensions of 2.5×2.5×1.2 m respect to base soil and it mix with 5, 10 and 15 percent shred tire. It should be notified that the soil in all four tests the soil are compacted based on guidelines of ASTM D6270-2006. The plate dimensions in PLT test are considered as 30×30 cm. The obtained results indicate that due to increase in shred tire percentage in the range of 5 to 15 percent, the maximum dry density decreases form 11.86 to 19.36 percent respect to the base soil. On the other hand the CBR value show 34.35 to 67.47 percent and Shear strength parameters such as cohesion the First, increased to 2.1 percent, but then decreased back to levels 27.1 percent and Angle of internal friction value has been reduced by 10.8 to 21.67 percent decrease in the mentioned range.Focusing on the obtained Ev2 values in PLT tests reveals a decrease of 27.54 to 54.29 percent in this matter. Comparing the achieved Ev2 results with those proposed by UIC R719-1996 code confirms the limitation of shred tire application to 10 percent for use in subgrade layer while its use in embankment is forbidden.