This paper uses the finite element method to analyse the mechanical behaviour of different track types by considering the different conditions to which they may be subjected: superstructure, height, embankment and foundation quality. The values of the stress and deformation as a function of depth are obtained at each point of the cross-section of the considered track. These values allow quantification of the basic design parameters for railway structures: track stiffness and stress supported by the railway platform. Optimal combinations of superstructure, height, embankment and foundation materials are presented for various specific operation conditions. The presented information can be used to improve the design of railway structures.

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Currently, reuse of solid waste from disused infrastructures is an important environmental issue to study. In this research, polymer concrete was developed by mixing orthophthalic unsaturated polyester resin, artificial microfillers (calcium carbonate), and waste aggregates (basalt and limestone) coming from the recycling process of concrete sleepers. The variation of the mechanical and physical properties of the polymer concrete (compressive strength, flexural strength, modulus of elasticity, density, and water absorption) was analyzed based on the modification of different variables: nature of the recycled aggregates, resin contents (11 wt%, 12 wt%, and 13 wt%), and particle-size distributions of microfillers used. The results show the influence of these variables on mechanical performance of polymer concrete. Compressive and flexural strength of recycled polymer concrete were improved by increasing amount of polyester resin and by optimizing the particle-size distribution of the microfillers. Besides, the results show the feasibility of developing a polymer concrete with excellent mechanical behavior.

A railway track stretch comprising three different track typologies (i.e., ballasted track, asphalt slab track and concrete slab track) has been modeled using a three-dimensional Finite Elements model, which has been calibrated and validated using real acceleration records. In this model, two different analyses have been run: a static analysis to assess the stiffness evolution and a dynamic analysis to calculate the accelerations induced by the train loads along the transition zones. These analyses have been used to assess the performance of three different techniques existing in the literature to improve the structural behavior of the track in the transition areas: the variation of the stiffness of the elastomers, the implementation of additional rails and the use of resilient mats. Results have demonstrated that these techniques perform generally better in the track vertical stiffness transition between the concrete and asphalt slab tracks while the dynamic response is not significantly altered in any scenario.

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