ESR-8 Fernando M. Soto

 “Characterization of rubberized asphalt for railway sub-ballast”

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SUP&R ITN Project is an Academia-Industry Training  Research Programme that aims to provide a multidisciplinary and multi-sectoral network in order to form a new generation of engineers versed in sustainable technologies, design procedures and environmentally sustainable assessment methodologies to certify the development of the transport infrastructure technologies.

About Me

Expertise in analysis, design, development and consulting structural computational-real models (mortar, concrete, asphalts) at various scales with experimental methodology non-invasive techniques, study of heterogeneous materials with conventional construction procedures and structural evaluation of elastic-strength parameters using non-destructive testing of vibration impact (NDT).

Diversified experience in Construction Technology (architect, draftsman-designer, computer graphics), continuous academic and professional training, focused on advanced structural design and research laboratory with isotropic materials. Currently developing experimental investigation of mechanical properties and internal defects using wave propagation techniques (SASW, IECO, FFRC, MASW, MISW …).

Determination of resistance and elasticity parameters, predictive structural monitoring and mechanical characterization.

Logo UGR         University_of_Nottingham

About Research

Characterization of rubberized asphalt for railway sub-ballasts (ESR8)

An attractive application to decrease the ground born vibrations produced by trains consists of using wet and dry rubberised asphalts in the sub-ballast layer. Although there are already a few studies related to these technologies, more research is needed in order to have a proper design procedure, to model the long-term performance and also to understand its sustainability.

Project Objectives:
• Provide an expertise on asphalt mix-design and materials;
• Define the representative test set for characterisation of the investigated materials;
• Determine the performance of rubberised asphalt for railway sub-ballast in terms both of mechanical behaviour and of ground-bourne vibrations;



Diversified experience in Asphalt Technology, academic and professional training, focused on advanced mix design and research laboratory with crumb rubber modified binders and rubberized asphalt  materials.
Currently developing experimental investigation of mechanical properties, resistance to fatigue, cracking, permanent deformation, strength and elasticity parameters. Perspectives to predictive structural monitoring and mechanical characterization.

The research is carried out within the framework of the Marie Curie Initial Training Network ‘SUP&R ITN – Sustainable Pavement & Railways’, opportunities to join network wide training events and international collaborations with at least two international partners. Universita’ degli studi di Palermo provides expertise with mix design, material selection and laboratory fundamental characterisation to predict performance in service. University of Nottingham and University of Granada provide expertise with a specific laboratory tests for railways infrastructures.

During this years other partners will be involved to provide the researcher with the knowledge of a specialised asphalt contractor and data for the life cycle inventory. Training events by experts and longer research missions at each partner facility allow for the acquisition of dedicated knowledge.

Research Development Activities

CRM           CRM Subballast

Recruitment: 1st September 2014: During this period I´ve being developing an expertise on asphalt mix-design and the representative test set for characterisation rubberized asphalt materials and understanding the behaviour on bituminous sub-ballast in railway construction.


  • Development of basic tasks in worksheets to study dosages and asphalt mixtures.
  • First steps in softwares (Ex. Kenpave, Pavement Design and Analysis by Yang H. Huang).
  • Development of SUP&R ITN workshops and training activities. 
  • Outreach dissemination activities & publications for technical journals and give input to seminars and conferences:
  • ” THE RESISTANCE TO FATIGUE OF DRY ASPHALT RUBBER CONCRETE FOR SUB-BALLAST LAYER” (13th International Conference & Exhibition Railway Engineering Congress, 1st July 2015, Edinburgh);
  • Elaborates abstracts & paper proceedings (Railway Engineering 2015 )  

    Introduction to Crumb Rubber Modifier on Dry Asphalt Concrete (DARC) mixtures for Sub-ballast layers

Crumb rubber is produced from grinding up whole scrap tires and other waste rubber products. Crumb rubber comes in a variety of grades and designations presented by particular size and/or source. Typically softer grades are used in blending asphalt rubber binder for a particular region than are used for production of conventional hot mix.

The bituminous sub-ballast layer within the ballasted rail track allows some advantages such as the decrease of ballast stresses and increase of the mechanical performance of the whole rail track. The bending behaviour of the sub-ballast is modelled by a viscoelastic continuous beam which is connected to the upper levels by means of spring-damping elements which take in account the vertical displacement of the layer.

The bituminous sub-ballast layer reduces the dynamic forces on the ground and achieves the technical objectives as reduction of ground borne vibrations and increase of the design life of the rail track. Notwithstanding DARC was not precisely designed for tracks bed purposes, within the analysed frequency range, it highlights a better results because of its viscous nature than ones obtained from sub-ballast with traditional asphalt concrete.

CRM Grades      


 Communication skills

This research is focused on experimental survey by mechanical tests on wet and dry rubberised asphalts for the sub-ballast layer. For developing this application is necessary to analyse new approaches, such as dissipation energy and to explain mechanical behaviour to the best. The most relevant accomplishments are both the formulation of fatigue law & permanent deformation of CRM asphalt; in addition to determine the parameters for rail superstructure design.

During this training period as Early Stage Researcher with PhD enrollment I´m developing personal presentation skills through videos, posters and writing presentations which provide involvement.

Example of Introduction to Fatigue law and mechanical principle of energy dissipation


 Contact me:

Department of Civil, Environmental, Materials Engineering (DICAM) Ingegneria Civile, Ambientale, dei Materiali, Viale delle Scienze, Ed. 8, 90128 PALERMO
Università degli Studi di Palermo, Italia +39 331 197 3172 (Italy);  +34 651 559 892 (Spain)

  Find me:


Informal enquiries on this specific project may be addressed to:                                                 Prof. Gaetano Di Mino,;                                                                              SUP&R ITN project to Dr. Davide Lo Presti,