Effect of Rubber Crumbs on the Cyclic Behavior of Steel Furnace Slag and Coal Wash Mixtures

Abstract

The practical application of waste materials such as steel furnace slag (SFS) and coal wash (CW) is becoming more prevalent in many geotechnical projects. While adding rubber crumbs (RCs) from recycled tires into mixtures of SFS and CW not only solves the problem of large stockpiles of waste tires, it also can provide an energy-absorbing medium that will reduce vibration and prevent track degradation. Thus, the engineering insight into the effect that rubber crumbs have on the dynamic behavior of SFS þ CW þ RC mixtures is in urgent demand. In this study the influence that RC contents and confining pressures have on the deformation, resilient modulus, damping ratio, and shear modulus was investigated by cyclic triaxial tests. Test results reveal that with the inclusion of RC, the axial strain, volumetric strain, damping ratio, and energy-absorbing capacity of the SFS þ CW þ RC mixture increase, while its resilient modulus and shear modulus decrease. Based on these properties, an amount of 10% RC is recommended as an optimal blended mix to be used as railway subballast. A three-dimensional (3D) empirical model of the relationship between the maximum axial strain, volumetric strain, and resilient modulus with RC contents and the effective confining pressure was developed, and the energy-absorbing capacity of these waste mixtures has also been analyzed for practical purposes based on their comprehensive parameters.

Application of geoinclusions for sustainable rail infrastructure under increased axle loads and higher speeds

“…Qi et al [55] established an energy-consumption flowchart based on the comprehensive properties of SFS + CW + RC mixtures ( Fig. 5).…”

“…The inclusion of rubber shock mats decreases the hard interface between the ballast aggregates and other track components, such as the sleepers or underlying formations, and allows the particles bedding into softer pads, thus enhancing the area of contact of the aggregates and minimising the inter-particle contact forces [42,47,51]. Moreover, indirect methods to reduce the degradation of ballast by using rubber products in the sub-ballast layer have also been proposed in recent times, such as replacing the traditional sub-ballast with an energy-absorbing layer composed of waste materials, including coal wash, steel furnace slag and rubber crumbs [28,55], and using a capping layer confined with recycled rubber tyre cells [17]. In this paper, some of these methods involving the use of recycled rubber products in rail tracks will be presented and discussed.…”

“…Optimising the blending ratio of SFS/CW, b-d optimising the RC content Data source:[28] and[55]; with permission from ASCE Page 5 of 21 69…”

Predicted Behavior of Saturated Granular Waste Blended with Rubber Crumbs

“…Membrane correction was applied for the test results obtained under ′ 3 = 10 , while for higher effective confining pressures the membrane effect was ignored as the error was less than 3% (Indraratna et al 2018;Lackenby et al 2007). In Australia, there are many low-lying coastal tracks in which the subballast is usually saturated by the high groundwater table (Qi et al 2018c). To predict the stress-strain behaviour more accurately, the influence of (%) on the critical state of SFS+CW+RC specimens compacted at 95% of their maximum dry density and sheared under three different effective confining pressures ( ′ 3 = 10, 40, and 70 ) have been studied.…”

The Influence of Rubber Crumbs on the Energy Absorbing Property of Waste Mixtures

“…Tsang et al (2012) found using rubber-soil mixture as an alternative seismic isolation material could significantly reduce the horizontal and vertical acceleration and displacements. The cyclic loading tests on rubber-waste mixtures conducted by Qi et al (2017b) reveal that the inclusion of RC could increase the damping ratio of the waste mixtures.…”