The railway industry has shown a strong interest in utilizing sustainable materials, including recycled materials and composites, in construction. Bamboo, as a highly renewable natural resource, has been proposed as a construction material for the railway industry. This material offers several advantages, such as high strength and durability, sustainability, low embodied energy, and ease of handling. It has been used in various construction materials like plywood, scrimber, laminates, and fibers. This paper aims to review the application of bamboo as a material in the railway industry and provide suggestions for its future use as railway sleepers. The mechanical properties of bamboo and its desirable features for sleeper construction, such as versatility, durability, low embodied energy and carbon footprint, lightweight, and ease of handling, are discussed. Bamboo-based products like plywood and scrimber can offer higher mechanical properties compared to traditional timber sleepers. Moreover, due to its rapid growth rate, bamboo is considered an environmentally friendly material. However, there are certain factors that limit the widespread deployment of bamboo in the railway industry. For instance, the lightweight nature of bamboo can reduce the lateral resistance of sleepers. Additionally, long-term performance studies and its performance in regions with varying weather conditions need to be further investigated. This review paper aims to promote the increased utilization of bamboo in the railway industry, contributing to the development of sustainable railway tracks. By considering the mechanical properties and advantageous characteristics of bamboo, it is possible to explore its potential as a viable and eco-friendly material for railway sleepers.@en

Transition zones between railway tracks and bridge decks can cause higher dynamic impacts. A solution is smoothly changing the track stiffness by gradually mixing steel furnace slag into the stone ballast. A nominated bridge transition zone is divided into 5 blocks of 7 meters long, with the mixing percentages of 0%, 25%, 50%, 75% and 100%. The mechanical behaviors of furnace slag-ballast combinations (FS-BCs) were studied using experiments of shear strength test, Los Angles abrasion index and plate load test. Furthermore, the dynamic behavior of bridge transition zone with FS-BCs blocks was investigated using a field validated FEM model. Results show that the 100%, 75%, 50% and 25% furnace slag by weight of ballast can increase the shear strength and ballast layer bending modulus by 13%, 12%, 9% and 7% at speed of 300 km/h compared with those of the stone ballast. The FEM study shows that rail deflections are reduced about 20%, 14%, 21% and 16% at speed of 300 km/h corresponding to 100%, 75%, 50% and 25% FS-BCs and accelerations are significantly reduced as well as increasing FS content of each block in bridge transition zone so that a smooth bridge transition zone can be achieved.

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In the present paper the mechanical behavior of two types of Kunststof Lankhorst Product (KLP) sleeper, namely low-density polyethylene sleeper (LDPE-16) and high-density polyethylene sleeper (HDPE-25) with 16 mm and 25 mm steel bars diameter, are studied. To this end, the static, dynamic, and longtime static three points bending moment tests are performed. The HDPE-25 and LDPE-16 with six strain gauges are mounted on the steel bars to assess their mechanical responses. Moreover, a Finite Element Method (FEM) model is developed to perform sensitivity analysis on 16 mm HDPE (HDPE-16) and 25 mm LDPE (LDPE-25) based on different steel bar diameters. The results showed that the LDPE-16 steel bar yielded under a load of 30 kN for 4 hours, while HDPE-25 showed significant resistance. Numerical results showed that HDPE-25 is overdesigned and can be replaced by LDPE-25, which is lighter in weight and lower in price. The natural frequencies of HDPE-25 were almost 16%, 19%, 16%, and 33% higher than the three first bending frequencies and first torsion frequency of LDPE-25, respectively. These findings prove the better performance of LDPE-25 in the case of preventing resonance. In addition, the exural modulus of HDPE-25 was almost 42%, 45%, and 65% higher than that of HDPE-16, LDPE-25, and LDPE-16, respectively.

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Recently, implementing steel slag ballast has been proposed as an appropriate material to substitute stone ballast. In this regard, one of the technical concerns is the behavior of steel slag ballast in both time and frequency domains that needs to be assessed, properly. Furthermore, the combination of stone ballast and steel slag is unavoidable in steel slag ballasted tracks during track maintenance concerning the limitation of steel slag resources. Therefore, this paper suggests an optimal stone ballast-steel slag (SB-SS) combination regarding the dynamic behavior of five SB-SS combinations as 0%SS, 25%SS, 50%SS, 75%SS and 100%SS by weight of ballast using a finite element method (FEM) model of a 50-meter test track. Moreover, using elasticity modulus and Moher-coulomb parameters obtained via a series of plate load and shear strength tests for each SB-SS combination turns FEM model to be more close to the real test track results. Experimental results show that adding steel slag particles to stone ballast increases elasticity modulus and friction angle of ballast layer resulting in the improvement of mechanical behavior of railway track. Consequently, the maximum deflections and root mean square (RMS) of accelerations decrease by increasing steel slag content. Analyzing free vibration of ballast layer combinations reveals that damping ratios of 100%SS ballast layer is the maximum value as 0.25 followed by 75%SS, 50%SS, 25%SS and 0%SS combinations. Moreover, the dominant frequencies of each ballast layer combinations determine that 0%SS, 25%SS and 50%SS coincides within the track excitation frequency range made by wheel sets, while 75%SS and 100%SS are out of which. Finally, according to all results, 75%SS ballast layer is proposed as the optimal SB-SS combination.

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