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According to research by DIP partner Aengevelt Immobilien, various innovations are leading to concrete becoming more climate-friendly and at the same time more efficient. Concrete had come under criticism because of its high CO2 emissions, so that building with wood increasingly came into focus. According to Aengevelt, the new technical developments can lead to a "rehabilitation" of concrete.
During the production of cement, carbon dioxide is released by the process, which is produced when limestone is burned at 1450 °C, when calcium carbonate breaks down into calcium oxide and carbon dioxide. The CO₂ is therefore not only produced by the fuel that brings the furnace up to temperature, but also by the chemical reaction of the raw material. Concrete production has so far been responsible for 8% of global CO2 emissions. For this reason, timber construction has gained significantly in popularity. Timber construction is not only playing a growing role in residential construction, but also in commercial construction, especially in the construction of production halls and warehouses. For example, the Timber Pioneer in Frankfurt am Main, an eight-storey office building with 14,000 m2 of office space was recently built in timber hybrid construction.
In the future, however, the use of concrete will also be associated with massively reduced CO2 emissions. For example, a complex technology has been developed at ETH Zurich in which not only no more CO₂ is released, but even 150 kg of CO2 are bound from the air per ton of cement. Although the calcium looping technology has been experimentally tested, it currently still requires a high level of electricity and is therefore not yet sufficiently economical. The cement manufacturer Holcim, on the other hand, uses a membrane capture of CO₂ from the exhaust gas at its Höver plant near Hanover, which can reduce CO₂ emissions by 90%. The technology was developed together with the Helmholtz-Zentrum Hereon and Cool Planet Technologies.
The start-up Dmat, which emerged from the Massachusetts Institute of Technology (MIT), is taking a different approach. Following the example of ancient Roman concrete, which has already lasted for 2,000 years, it has developed a concrete additive that can independently close small cracks by recrystallizing calcium compounds. The service life of concrete structures is to be extended by 50% through the self-healing concrete. At the same time, CO₂ emissions are reduced by 40%. The innovative concrete has already been used in Italy and Switzerland in the construction of motorways and technical infrastructure.
The third innovation is infra-lightweight concrete, which is produced with low CO2 emissions from recycled concrete rubble and even binds CO₂ from the air due to its carbonation potential. Infra-lightweight concrete has a high static strength on the one hand and excellent insulating properties on the other, making it suitable for monolithic exterior walls without further insulation. Compared to external thermal insulation composite systems, it even offers significantly better thermal insulation in summer because it can dissipate interior heat in the cool of the night. Concrete can also be used for particularly energy-efficient heating/cooling systems with component activation or concrete core activation, for solid absorbers that extract ambient heat from the air, soil, groundwater or bodies of water, for heat storage systems such as solid-water storage tanks and ice storage tanks, and for solar concrete that generates electricity from solar energy. Examples of buildings made of infra-lightweight concrete are the Grolmanstraße office building in Berlin-Charlottenburg, the REWE supermarket in Berlin-Friedrichshain, the youth leisure centre in Berlin-Lichtenberg and several single-family homes.
Dr. Wulff Aengevelt, Managing Partner of DIP partner Aengevelt Immobilien: "Thanks to various innovations, it is now possible to build with concrete again without a guilty climate conscience. By combining various innovations, carbon dioxide emissions are reduced to practically zero; concrete buildings can even become CO2 sinks. Service life and thermal properties are even improved. This relativizes a serious argument of radical climate protectors against the construction of new buildings."
