Waste tire-derived aggregates-ballast mixture degradation analysis by Los Angeles Abrasion test and 3D image analysis method

Abstract

At present, the railway transportation system has become an important role in the development of transportation systems in Thailand. Ballast is an important component of the railway structure. After a period of use, ballast track will deteriorate, affecting its distribution, subsidence, and contamination of small particle materials. Previous research has studied various materials to extend the service life of ballast, but there are still limitations due to higher costs. This research presents a study of the deterioration of ballast mixed with scrap tires by analyzing the wear resistance in different proportions and sizes of tires under dry conditions and analyzing the surface morphology from 3D scan images. The experiment used 3 types of scrap tires: cubes, rods, and disks. The rock samples were scanned with a 3D scanner and tested for wear resistance at 100, 500, and 1,000 rotations, mixed with scrap tires in proportions of 5%, 15%, and 25% by volume. In each rotation, the same sample was used for testing, alternating with scanning after the LAA test. The study found that increasing the proportion of scrap tires reduced ballast wear, with the cube-shaped scrap tires having the best effect on reducing wear. The rod and disk shapes were followed by the slab shapes. When the proportion of scrap tires increased to more than 15%, the decrease in wear depth was not significantly different. The morphology study with SHF showed that the shape of the scrap tires had a significant effect on the change in the physical characteristics of the stone particles, especially the angularity index (AI3D) and the surface texture index (MT3D), where the cube rubber scraps had the least change compared to the other shapes. In addition, the roughness radius of the cubic rubber scraps had the lowest value in all mixing ratios, indicating that the rubber scraps could effectively reduce the wear of the stones, especially when the rubber scraps ratio was 15%, which resulted in the least reduction in wear rate.