A Study on the angle of repose of railway ballast mixed with rubber tyre fragments: A comparative analysis between new and used railway ballast

Abstract

Ballast is an important component of railway system with the advantages of low cost, short construction period and vibration reduction efficiency. However, the current increase in train speed has resulted in the accelerated deterioration of ballast, which leads to stability and safety problems. This study focuses on solving this problem by using scrap tires as a composite material in ballast to extend its service life and improve its efficiency. The ballast angle of repose test, which reflects the angle of internal friction, is an important indicator of the ballast's shear resistance. This paper presents a study on the angle of repose of ballast mixed with scrap tires in different proportions and shapes, comparing them with fresh ballast and used ballast, which were subjected to abrasion resistance tests (Los Angeles Abrasion Test) at 500 and 1,000 cycles. The scrap tires were prepared in three shapes: cube, rod, and disk. The pile angle test was carried out using PVC pipes with an inner diameter of 30 cm and a height of 90 cm. The pipes were lifted by a crane and the piles were scanned using a FARO Focus 3D scanner. The results showed that: The angle of repose of fresh ballast is higher than that of used ballast. In addition, the cube shape of scrap tires results in the highest slope angle, followed by the rod shape and the disk shape respectively. When the rubber ratio is more than 15%, the angle of repose of ballast is significantly reduced.