Large quantities of cement and aggregates are required due to the currently predominant concrete construction method. With a_{CO2 equivalent of} approx. 600 kg_CO2 per ton of cement (values for Germany), cement production is responsible for 17% of Germany's_{CO2 emissions} in the industrial sector. Valuable rock resources are extracted for the production of aggregate for concrete, particularly in Germany, leaving traces in the environment. Not only the impact at the extraction site is considerable, but also the transportation to the place of use and processing.

However, recycling materials can also be used in this area: The demolition of existing concrete structures generates large quantities of demolished concrete, which at present is often only used as backfill material, particularly in road and sewer construction. We can therefore speak of downcycling.

The use of recycled concrete is a promising approach to improving the sustainability of the construction industry. Based on the findings of extensive research projects, standards and guidelines have been developed according to which some of the aggregates used may consist of demolished and recycled concrete. Since the latest normative development (DIN EN 197-6), the fine fractions of the demolished material may also be used as a filler in cement. No significant reactivity of the recycled material is assumed here, but there are promising approaches to applying_CO2 to the fine fraction and thus enhancing its quality on the one hand, but also using it as permanent_{CO2 storage}.

_CaCO3 is formed during the carbonation of the concrete powder, but amorphous silica gel can also be formed, which has pozzolanic reactivity.

Together with the cooperation partners WENOWA and Marpe Bau, the potential for processing recycled material from the region, applying_CO2 and thereby producing both RC aggregate and cement substitutes is to be examined. The newly manufactured products are to be used directly in the region, thereby saving on transportation costs. As part of the research project, the production of concrete products with alternative binding agents will also be investigated. Here, cement is dispensed with completely and the solid reacts with an alkaline stimulant to form products that can have high strengths and similar properties to concrete. The contribution of carbonated concrete powder is a particular focus of the investigations.