Adjustment and application of CO2-efficient composite admixtures (calcined clay - sulfate carrier - limestone powder) for control of concrete properties

• Applicant: Dr.-Ing. Nancy Beuntner
• Subject Area: Construction Material Sciences, Chemistry, Building Physics
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 519196620

The concrete industry uses supplementary cementitious materials to reduce cement consumption and the associated CO2 emissions. The use of these replacement materials can influence various properties (e.g. heat development) that are relevant concerning specific applications. Since a large proportion of supplementary cementitious materials used today, e.g. fly ash, originate from CO2-intensive processes, their availability is not given in the long term. The concrete industry is therefore urgently dependent on the development of new replacement materials. In this context, materials based on calcined clays provide the greatest potential. In the underlying DFG project, fundamental mechanisms regarding the influence of the most important phyllosilicates occurring in clays on cement hydration were explored using model systems. A clear dependence on the composition of the three-component mixture consisting of calcined clay, sulfate carrier and limestone powder was found. In the planned project, therefore, optimally adjusted composite materials shall be developed and adapted with regard to the application-related target parameters. To this end, various raw materials will first be selected and analyzed. The findings from the preceding DFG-funded project will then first be transferred to real cementitious systems and concretes on a laboratory scale. Afterwards, these results are to be scaled up to the pilot plant scale in order to provide appropriate quantities for the development of demonstrators. Large-scale trials at the application partner will then show whether existing products can be produced with at least equivalent quality using the newly developed composite materials. This is to show if supplementary cementitious materials from CO2-intensive processes can substituted adequately. In addition, tools for rapid formulation adaptation, in the event of changes in raw material compositions or concrete property requirements, are to be developed. This shall be complemented by the preparation of recommendations and a practical guide for the concrete industry. Finally, the demonstrators produced will be compared with reference products in the course of a life cycle assessment.

• DFG Programme: Research Grants (Transfer Project)
• Application Partner: TBS Transportbeton Rhein-Neckar GmbH & Co. KG
• Cooperation Partner: Dr. Matthias Maier