Assessment of Performance of Recycled Ballast Aggregate Subjected to Drop-Weight Impact Loading Considering Effect of Crumb Rubber Incorporation

Abstract

Degradation of ballast aggregate subjected to applied train loads can adversely influence the performance of ballasted railway tracks. Meanwhile, replacement of degraded aggregate with fresh material can engender some environmental concerns due to the necessity of implementing a scheduled maintenance program on ballasted railway tracks. Therefore, using recycled ballast material combined with fresh aggregate derived from rock quarries is characterized as an appropriate maintenance strategy. In the present study, various percentages of recycled ballast are combined with fresh aggregate, then the performance of prepared specimens against degradation is investigated by conducting a large-scale drop-weight impact loading test. Furthermore, the effect of addition of discarded crumb rubber particles on the degradation resistance of the prepared specimens is evaluated. Generally, the recycled aggregate exhibits higher level of degradation due to spitting individual particle, although the generation of fine particles considerably decreases. Likewise, the combination of various portions of recycled and fresh aggregate shows that further reduction of proportion of recycled material leads to the exacerbation of the fouling level and reduction of the breakage of single aggregate. Furthermore, the incorporation of discarded crumb rubber particles among prepared mixtures of recycled and fresh ballast aggregate evidently enhances the performance of recycled/fresh mixtures of aggregate especially for lower percentages of recycled aggregate.