Concrete is responsible for almost eight percent of global CO2 emissions. In Soltau, a new technology is being used for the first time that could massively reduce emissions.
Antonio Catarino has been working towards this day for ten years: “We have the technology to make a big contribution to decarbonizing the construction industry,” says the boss of the concrete manufacturer Bton. Together with his colleagues, he opened the first factory in Germany to produce “climate-positive” concrete in Soltau in the Heidekreis. Climate positive means that more CO2 is saved than is consumed. The heart of their production is a new mixing technology – carried out on a mixing tower that, according to Catarino, is unique in the world.
Production in two steps
Previously, when making concrete, water, sand, gravel and cement were mixed together at the same time. In order for water and cement to react with each other and for the concrete to harden, clinker was always necessary in the cement. This clinker is produced at high temperatures and uses a lot of energy and CO2.
The new mixing tower in Soltau now uses significantly less clinker. Concrete is produced in two steps. First, just water and cement are mixed together. The so-called hydration, i.e. the “activation” of the cement particles through contact with water, works faster and more effectively without the other additives sand and gravel. Therefore, cement that contains less clinker can be used here. According to the operator, this alone can save up to 80 percent of CO2. Sand and gravel are only added in the second step.
Concrete should become lighter
The Bton company invested a total of 9 million euros in the new factory. According to managing director Thomas Demmel, the material that they obtain using the new mixing technology has the same quality as conventional concrete and does not cost any more. Concrete becomes climate-positive if carbon-reducing materials are added to the mixing process. In the end, more CO2 is absorbed than was used in the entire production process.
“We believe it’s a game changer technologically,” says Demmel. Especially because it is also possible to make the concrete produced in Soltau 40 percent lighter than before. This saves resources. In addition, the new mixing technology can also use sand that is not coarse-grained and could not be used in previous concrete mixing plants, including desert sand.
economics as a sticking point
However, in order to make the construction industry permanently more climate-friendly, production must be massively expanded. Bton plans to produce walls and facade elements for 1,600 to 2,000 apartments at its factory in Soltau next year. That alone is not enough for the big hit. That is why further plants in Germany and abroad are to follow. The first inquiries and orders come from Brazil, the USA, Singapore, Dubai and Saudi Arabia.
For Thorsten Leusmann, concrete expert at TU Braunschweig, economic efficiency is the central challenge when it comes to investing in new plants. “If the company can implement everything it sets out to do, it will encompass a broad spectrum of what is currently being explored in concrete technology.” The only question is whether it is not too ambitious to try to solve several large problem areas in a single work.
It is also clear to the managing directors Catarino and Demmel that they need more partners and more money. But it is expected that they will quickly find their way into the market. In addition to production, the plant in Soltau is also intended as a training facility, which will be used as a basis for the next precast production facilities at home and abroad.