This paper presents a comparative study on the shear behavior of coal fouled polyurethane-stabilized and polyurethane-stabilized coal fouled ballast. Fresh granite ballast and coal fines of mean particle sizes (D50) of 42 mm and 545 microns, triangular aperture geogrid and Elastan polyurethane polymer with a density of 1100 kg/m3 were used in the current study. Tests were performed at different normal stress (σn) ranging from 60 to 120 kPa and at a constant shearing rate (Sr) of 3 mm/min. To simulate the effects of coal fouling, a predetermined quantity of coil was added that represents a fouling level, void contamination index (VCI), of 30% in the current study. The test results highlighted that polyurethane stabilization technique significantly enhanced shear strength of ballast. However, the coal fouling reduced the shear strength of both stabilized and unstabilized ballast. The friction (φ) and dilation (ψ) angles of stabilized and unstabilized ballast were found to decrease non-linearly with an increase of σn. Furthermore, the friction (φ) and dilation angles (ψ) of unstabilized ballast is found to decrease from 65° to 60° and 21° to 16°, respectively due to coal fouling. The stabilization efficiency factor (Sef), defined as the fraction of the shear strength of stabilized ballast to that of unstabilized ballast, varies from 1.61 to 1.75 for polyurethane-stabilized ballast as σn varies from 60 to 120 kPa. Moreover, it is observed in coal fouling conditions that the coal fouled polyurethane-stabilized ballast shown better performance when compared to polyurethane-stabilized coal fouled ballast.

Stabilization of Railroad Ballast Using Polyurethane Under Various Coal Fouling Conditions

Paper Proceedings: https://asmedigitalcollection.asme.org/JRC/JRC2021/volume/84775

2021 Joint Rail Conference (JRC2021)

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