چكيده به لاتين
It has become very important to replace stone ballast with steel slag as a result of environmental concerns and to protect rock resources. A large volume of steel slag is produced and stored in recent years, resulting in the need to recycle this product. Several studies have been conducted to study steel slag's physical and mechanical characteristics. The results show that steel slag follows all the standard requirements and is not prohibited for use in ballast tracks. One issue that should be considered in steel slag ballasted tracks is that due to limited steel slag resources, stone materials will be forced to combine with slag materials in ballast track maintenance. It is essential to identify the physical and mechanical properties of this composition. In this thesis, to investigate the dynamic behavior of rock ballast-slag ballast (RB-SB) composition, first, the properties of materials were evaluated and compared using X-ray diffraction equipment (XRD and XRF), Then, by defining five RB-SB combinations as 0%SB, 25%SB, 50%SB, 75%SB, and 100%SB by weight of ballast using, dry and wet wear of the samples was investigated by performing Los Angeles and micro-Deval tests. Finally, the SB-SS has been evaluated under cyclic load by performing the ballast box test and calculating the ballast deterioration, the stiffness, and the damping ratio for each sample after applying 100,000 loading cycles. XRF test showed that the main constituents of steel slag are Fe2O3, CaO and SiO2, and for stone ballast is SiO2 and Al2O3. According to the results of Los Angeles and micro-Deval experiments, steel slag wear in the dry state was 23% higher than the wear of stone ballast, but in the wet state, the wear rate of steel slag was 31% less than that of stone ballast. The results of the ballast box test show that the amount of settlement for steel slag is 33% less than for stone ballast. The crushing rate of steel slag is more than stone ballast, and BBI for steel slag is 0.1381, and for stone ballast is 0.0558. By the hysteresis loop, the amount of stiffness and damping ratio was calculated for SB-SS. The results show that the use of steel slag increases the stiffness of the ballast layer. Compared with 0%SB, stiffness increased by 3, 15, 31 and 35% respectively for 25%SB, 50%SB, 75%SB, and 100%SB. The damping ratio also increased with greater percentage of steel slag in the sample, so that 25 %SB, 50 %SB, 75 %SB, and 100%SB damping ratios increased by 6, 18, 51, and 76%, respectively, compared to no steel slag. In conclusion, based on the obtained results, the sample containing 75% steel slag and 25% stone ballast is recommended as the optimal composition.
