Deutsche Bahn wants to become climate-neutral by 2040. To achieve this goal, they are relying on various levers and measures - including the use of innovative and resource-conserving building materials. With recycled materials and by testing new eco-concretes and binding agents, stations are to be made more climate-friendly in future - for example with the use of eco-pavers on the platforms or on the station forecourt.
Formerly construction debris, now recycled paving stones
Eco pavers bear their name for a reason. They are manufactured using innovative and environmentally friendly production processes that use renewable energy and treated rainwater, among other things. In addition, so-called concrete block chippings are used. Up to 40 percent of the material that used to end up in road construction can be found as recycled material in the eco paving stones that DB has been using since 2014. Since then, several stations have already been paved with the recycled stones - for example at the Westfrankenbahn and at Weiterstadt, Laudenbach (Württ) and Sulzbach (Main) stations.
Südkreuz pilot project: practical test for climate-friendly eco-concretes
The high cement content in concrete is a major driver of CO2 emissions in the construction of infrastructure facilities and buildings. Billions of tons of concrete are produced worldwide every year. Cement clinker acts as a binding agent. These are fired at peak temperatures of 1,450 degrees in what is known as a rotary kiln. Here, the calcium carbonate from the limestone is converted into calcium oxide and carbon dioxide. This process is responsible for the majority of CO2 emissions from conventional concrete production. Around a third of CO2 emissions are caused by heating the kilns - for example with the help of coal and natural gas. The remaining two thirds are caused by the chemical reaction.
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Eco-concrete at Berlin-Südkreuz station
In order to reduce CO2 emissions during construction in the future, Deutsche Bahn is therefore testing new ecological concretes in a pilot project at Südkreuz station in Berlin. These eco-concretes are characterized by a reduced clinker content, alternative materials and energy-saving production and produce up to 60 percent less CO2 compared to the industry average. Nine floor coverings from six manufacturers were laid over an area of around ten square meters. Testing began in April 2025 and will continue over a period of twelve months. This means that all weather conditions - from summer heat to winter frost - can be taken into account and their effect on mechanic properties such as resistance to freeze-thaw, abrasion resistance and slip resistance as well as optical resistance can be examined.
In addition to the climate-optimized concretes, solar coverings are also laid out in the middle of the test area. A paving stone with a 25 percent recycled content, which is already used as standard at DB, is also installed as a reference surface.
Focus on materials and processes:
Alkali-activated binders
Alkali-activated binders (AABs) known as geopolymers - are alternative binders for the production of cement clinker-free materials. These include, for example, blast furnace slag, fly ash or slag in combination with an alkaline activation solution. This causes significantly lower CO2 emissions during production than conventional cement use.
Various floor coverings with alkali-activated binders are used in the pilot project. The materials used are cement-free in the core concrete and, according to the manufacturer, contribute to an average reduction in CO2 emissions of up to 60 percent compared to the industry average.
The following floor coverings were tested:
- RINN Klimastein
- KANN PROKLIMA
- Berding beClimate
- Kronimus stone with cement-free backing concrete
The floor coverings are characterized by high strength, chemical resistance and durability.
Clinker-reduced cements
In addition to clinker alternatives, floor coverings with a reduced proportion of clinker were also installed. For example, the use of other main components such as limestone, granulated blast furnace slag, fly ash and volcanic ash can further reduce CO2 emissions during production. Depending on the composition, a distinction is made between six cement classes (CEM I to VI), with CEM I corresponding to conventional Portland cement clinker.
In the pilot project, CEM II flooring from Kronimus and Lithonplus are each used. Both save around 40 percent CO2 in production compared to the conventional industry mix.
More innovative approaches
The KANN PROKLIMA Zero is a concrete block that contains biochar. This is obtained by heating biomass from residual and waste materials in the absence of oxygen. The use of this carbon improves the material properties such as moisture regulation and thermal insulation and helps to reduce the carbon footprint of the concrete.
The Platio solar coverings offer two advantages: Firstly, they are made from recycled plastic, and secondly, a solar cell is integrated into the flooring, which collects the energy from the incident sunlight.
By working closely with the various manufacturers, DB wants to find out which solutions meet the operational requirements and at the same time gain experience in order to build climate-friendly platforms and station forecourts in the future.
