Project description

The aim of the project is to develop a highly CO₂-reduced, high-quality and resource-efficient concrete cycle for old concrete. For this purpose, a belite-based Portland cement clinker (RC clinker) with a low CO₂ footprint will be produced from concrete crushed sand for the first time. Released CO₂ can be separated in a concentrated manner and used for the technical carbonation of either mechanically processed concrete crushed sand as a substitute in cement or for carbonation hardening of coarse RC rock formation (CCU) using a new process based on a pressure autoclave.

Recycled cements with a greatly reduced CO₂ footprint are formulated from recycled bricks, Portland cement clinker and technically carbonated crushed sands as well as other substitutes. In order to enable its use in production, recipes for RC2 concretes based on adapted superplasticizers and accelerator systems are developed from recycled cement and recycled aggregate. At the end of the project, plant tests will be carried out to demonstrate the high-quality concrete cycle using the example of concrete products and precast concrete elements.

The research approach is evaluated technically, economically and ecologically for different plant sizes and locations over the entire life cycle and compared with the state of the art. The aim is to reduce the cumulative CO₂ emissions of RC2 concrete by at least 40% compared to conventional recycled concrete.

In addition, regulatory boundary conditions are examined (e.g. Recycling Building Materials Ordinance, DIN-EN 197-1, legal classification of a plant for clinker production) in order to identify obstacles in the implementation of centralized or decentralized concepts.