Climate Concrete

How do we solve the challenges of our time? Do we have to put all our forces into new innovations, or will we also be able to work with what we know – only in a modified way? Might it even be possible to work with materials that still have a high carbon footprint and a corresponding reputation to limit greenhouse gas emissions and even create net carbon sinks? We have tried it with some of the most challenging, but also indispensable materials, just recently with concrete. Spoiler: It worked!

Concrete, particularly the annual production of 4,1 Gt of cement, are responsible for about 8% of global greenhouse gas emissions. At the same time, concrete is indispensable with regards to urbanization and population growth we are facing globally. Whether this versatile and convenient material will go down in history as a climate killer or a climate saver is not on us as the biochar industry, but we are just about to prove that it could be the latter.

Left picture: First conventionally produced CarStorCon® by Kopf Kies+Beton in cooperation with EnergieWerk Ilg, Carbon Instead, EBI, Carbonfuture, SynCraft and Ingenieurbüro Axel Preuß; Right picture: direct comparison of climate-controlled concrete (left) and conventional concrete (right).

Alternatives to sand and gravel are already being used for concrete production. A lot of effort is being put into pursuing and optimizing the replacement of cement by using granulated blast furnace slag and similar alternatives. This will help to reduce the footprint of currently around 521 kg CO2/t of cement. Also, possibilities to capture the emitted CO2 at the chimney of the cement plant by means of CCS (Carbon Capture and Storage) technology are highly in demand in view of rising CO2 prices and will certainly find application in the next decades. But, in order to generate truly climate-positive effects with concrete, major changes and more than emission reduction are needed. EBI members Axel Preuß, SynCraft, Energiewerk Ilg, Carbonfuture and further partners are focusing on the use of sustainably produced, engineered carbon, which ensures that concrete becomes a noticeable long-term carbon sink, as shown in the illustration below.

We have succeeded in making up the technical carbon in such a way that a net climate-positive effect of concrete is achieved. With regards to the physical properties, repeated test series have already shown, that they have been significantly improved. In terms of both compressive strength and surface properties, the climate concrete is in no way inferior to its conventional counterpart. “On the contrary, it looks as if significant improvements can be achieved with it,” says Axel Preuß, concrete technologist from Osteel, northern Germany.

So this is the birth the first concrete that is not only climate-positive, but also scores with added value compared to its conventional concrete counterpart. The Carbon Storage Concrete technology (CarStorCon®) is a graspable, sustainable and permanent carbon sink, a real Negative Emission Technology (NET).

The basis of the technology is the specially designed aggregate Clim@Add®. It consists of 98% technical carbon. This technical carbon is produced as a by-product of climate-positive energy systems. In addition to carbon, these systems also provide sustainable, regional electricity and heat from forest residues, helping to decarbonize other industries.

By substituting 15% cement with 15% Clim@Add®, it is possible to produce climate-positive concrete whose properties are at least equal to, and can even exceed, those of a corresponding reference concrete (C25/30). It is ideal for processing and thus offers a wide range of application possibilities. In addition to the climate-positive properties that the concrete acquires through the use of Clim@Add, its technical properties also are positively influenced. The high compressive strengths of the CarStorCon® technology are one effect, as well as the improvement of the internal curing, the improved sound insulation or the more optimal thermal insulation behavior as well as the significantly better moisture-regulating properties.

This technology has what it takes to turn a climate killer into a climate saver. For this to succeed, expertise and effort have to be bundled. In2ovation has taken over the technology and is currently developing an appropriate marketing concept. In a large-scale research project with the Federal Institute for Materials Research and Testing in Berlin, the next development step is being supported, so that CarStorCon® can quickly come to maturity.

Despite all the hurdles that climate concrete still has to overcome before it can be used as a matter of course in all possible areas, one thing can already be said. The path to not only climate-friendly concrete, but even to climate-positive concrete is clear. We just have to walk it together and probably go even further….

The team behind CarStorCon®/Project partners:

F.r.t.l: Hannes-Junginger Gestrich / Carbonfuture.earth, Tobias Ilg / EnergieWerk Ilg, Julia Roth / Carbon Instead, Harald Bier / EBI, Axel Preuß / Ingenieurbüro Axel Preuß, Marcel Huber / SynCraft