The construction industry is not exactly considered climate-friendly. The reason: cement production. Researchers at the Fraunhofer Institute for Building Physics are now developing concrete that even binds climate-damaging CO2.
Oberlaindern
– Demand from industry is already growing, reports Professor Gunnar Grün, deputy head of the Fraunhofer Institute for Building Physics (IBP) in Oberlaindern near Holzkirchen. “We already have inquiries from companies.” The CO2 price is rising. And this makes it increasingly lucrative for companies to save carbon dioxide emissions. IBP researchers have developed a method that can help the construction industry and concrete manufacturers significantly reduce their carbon dioxide emissions: they bind carbon in building materials. How was explained to Bundestag member Karl Bär (Greens) from Holzkirchen during a visit to the institute by Grün as well as Christian Kaiser, group leader for materials and process development, and Volker Thome, head of the mineral materials and building materials recycling department.
Researchers are working on building materials of the future
The construction industry is one of the tricky industries. Not just because demands would increase due to climate change. But also because it uses a lot of finite raw materials and the CO2 emissions in the production of conventional concrete are very high due to the cement it contains. IBP researchers are working on more climate-friendly and ecological solutions. It's not just about real recycling, like electrodynamic fragmentation, with which old concrete is broken down into its original raw materials, which could then be reused (we reported). But also about the development of completely new building materials.
Cattail panels for interior work
Like the Typhaboard: The panels are pressed from the leaves of fast-growing cattails. The building material can be used in interior construction for insulation and soundproofing, is mold-resistant, offers a high level of fire protection and can be completely composted. Or like the so-called carbon capture concrete (CC concrete), which – as the name suggests – binds carbon. In the form of pyrochar, which can be produced by heating in the absence of oxygen from pressed plant sections, but in principle from any organic material - even from old rotor blades from a wind turbine. When mixing concrete, this pyrochar partially replaces the usual cement-containing binders.
A concrete that binds carbon dioxide
The IBP team demonstrated to the Bundestag member in one of the laboratories that and how it works. The researchers are convinced that this CC concrete has what it takes to sustainably change the construction industry. “This gives us a negative emissions product,” explains Kaiser. “This means that our process binds more carbon dioxide in the concrete than is emitted during production.” The sustainable building material is comparable to conventional concrete in terms of its technical properties and strength.
Green MP visits the institute
Bär was very interested in the materials, but also asked about the disadvantages. “After all, asbestos was once the 'miracle fiber',” he noted in the discussion with the researchers. Pitfalls are often only discovered later. With regard to the Typhaboard, the MP pointed out that a struggle had broken out over biomass that could not be withdrawn from the natural cycle indefinitely. The pyrolysis of the pyrochar for the CC concrete also consumes energy. Thome explained that it could also supply biofuel instead of natural gas.
It won't work without concrete
It is clear to the researchers that construction will certainly not be possible in the future without materials such as concrete, especially not for infrastructure construction. This requires more ecological alternatives than sand and cement. And for their development, research and industry need political support. The head of the institute wants to appeal for this at the highest level on the sidelines of the Ludwig Erhard Summit in Kaltenbrunn: with Federal Construction Minister Klara Geywitz (SPD). A competence center for sustainable construction, says Grün, referring to the IBP, “has been here for over 50 years”.