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Slag layers in railway foundations

European Union
Geo-spatial type
Project Acronym
STRIA Roadmaps
Transport electrification (ELT)
Low-emission alternative energy for transport (ALT)
Infrastructure (INF)
Transport mode
Rail icon
Transport policies
Environmental/Emissions aspects
Transport sectors
Passenger transport,
Freight transport


Background & Policy context

According to the World Steel Association, the European Union produced 177.2 million tonnes of crude steel in 2011.

Steelmaking can be carried out by basic oxygen steelmaking – primary steelmaking – in which oxygen is blown through molten pig iron. Another process is the Electric Arc Furnace (EAF) – secondary steelmaking – in which scrap metal and/or pig iron is directly exposed to an electric arc and melted down.

A by-product of both processes is steel furnace slag (SFS) which forms on the surface of the molten steel. EAF production – which accounts for some 42.8% of the total - generates up to 15 % of slag/tonne of steel. It is usually composed of molten metal oxides, silicates and ferrites, although the exact composition varies depending on the particular conditions of production. Currently, a great volume of slag is dumped, although there is increasing research into different application alternatives. One of the most important is as a recycled aggregate in road construction, as material for road foundation layers.


The LIFE GAIN project aims to demonstrate the feasibility of using SFS as an eco-friendly aggregate in the construction of railway tracks – specifically to form sub-ballast and sub-grade track foundation layers, a completely new technological solution. The ultimate goal of the project is to reduce the large volume of SFS that is annually disposed in landfills.

The project will produce a new eco-friendly aggregate - SFS-Rail – in valorisation plants. It plans to locate these plants next to steel furnaces to minimise the frequency and intensity of transport. A key feature will be the demonstration that it is possible to adapt an existing valorisation plant to produce the new material.

The project plans to construct 100 m-long test sections of rail. It will then use these to monitor the eco-friendly aggregate’s performance and hopefully demonstrate the predicted benefits of the material. Beyond showing that it is a technically feasible application for recycled SFS, existing research suggests that the project can hope to prove that its mechanical properties – strength, hardness etc. – will actually make it a more durable and sustainable product than natural aggregates.

LIFE GAIN hopes to show that SFS-Rail is an innovative, sustainable and eco-friendly alternative to natural aggregates, applicable throughout Europe. It expects to demonstrate that the technology used to produce SFS-Rail will be easily transferrable to other European countries where there are a large number of furnaces currently facing the same environmental problem.

Based on the application of SFS-Rail in the test sections of the project the expected results are:

  • Reduction of the volume of the annual slag disposal on landfills by 1 078 tonnes – with a potential reduction in Europe of 360 000 tonnes/yr;
  • Reduction of the use of natural aggregates by 1 078 tonnes – also with a potential reduction of 360 000 tonnes/yr;
  • Reduction of the environmental impact at quarries;
  • Reduction of the frequency and intensity of transport of SFS;
  • Reduction of energy consumption by 197.5 Mkwh - with a potential reduction in Europe of 65 909 Mkwh/yr;
  • A reduction in overall CO2 emissions of 6.03 tonnes – with a potential reduction of 2 014 tonnes/yr; and
  • Reduction of other environmental impacts, including deforestation, the impact on vegetation and fauna and hydrological impact.



Parent Programmes
Institution Type
Public institution
Institution Name
European Union
Type of funding
Public (EU)


Lead Organisation
EU Contribution
Partner Organisations
EU Contribution


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