Carbon Capture & Utilization



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CO2 integration in recycled old concrete

zyklus Carbon Capture Copyright: © AMR

Global development in terms of population growth, associated urbanization and economic progress is increasing the demand for new buildings and infrastructure - and thus for concrete.

Already today, concrete is the second most used material by humans in terms of mass after water. Although concrete has low specific CO2 emissions of less than 150 kgCO2,eq/t of concrete, the amount used makes it responsible for 5-8% of man-made CO2 emissions. Most of the CO2 emissions from concrete come from the production of cement clinker, the main component of concrete. These emissions are process-related from the calcination of the limestone. By substituting the cement clinker, a reduction in CO2 emissions is possible.

Sustainable reduction of CO2 emissions

The primary objective of the transdisciplinary research project called C2inCO2 is to exploit the potential of recycled waste concrete for CO2 capture and to use it as a building material. Through the development of optimized treatment processes and efficient carbonation processes, it includes the two central building blocks required to close the CO2 and material cycle in the cement and concrete industry and thus significantly reduce CO2 emissions.

As part of the project, Vincent Merz from the AMR (Unit of Mineral Processing) teaching and research area is researching preparation processes for optimal product generation for downstream processes. The focus is on selective comminution of the concrete into its constituents sand, coarse aggregates and concrete fines, which is as pure as possible, and subsequent separation of the comminution products.

Another research focus is the implementation of a sensor-based, online realizable characterization of the cement paste content. In the relevant material flows, an effective quality assurance is aimed at in order to optimize the separation process of the gravel and sand fractions from the old concrete.