Optimisation of clinker melt for sustainable cement production

• Applicants: Dr. Matthias Böhm; Dr. Christiane Rößler
• Subject Area: Construction Material Sciences, Chemistry, Building Physics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 575010888

The production of Portland cement clinker has been optimized over two centuries to ensure high product quality while minimizing energy consumption and CO₂ emissions. While the European cement industry is increasingly focusing on carbon capture, storage, and utilization (CCSU) technologies for full decarbonization, these approaches are cost- and energy-intensive. Therefore, reducing CO₂ emissions at the source remains a crucial first step. This project aims to deepen our understanding of clinker melt properties and their influence on phase assemblage and reactivity. Specifically, we investigate how minor and trace elements affect melt formation, with the goal of optimizing clinker production. Previous studies have shown that melt composition can lower the alite formation temperature and enhance cement reactivity. These effects are highly relevant for sustainability: lower burning temperatures reduce energy demand, and higher reactivity enables greater clinker substitution with low-CO₂ supplementary cementitious materials (SCMs) without compromising performance. To achieve this, we will apply state-of-the-art analytical techniques and novel experimental approaches to control melt formation and characterize its properties in detail. WP1 focuses on systematic variation of clinker melts composed of C₃A and C₄AF by adjusting the alumina-to-ferric oxide (A/F) ratio and introducing dopants. We will investigate key melt properties such as formation temperature, viscosity, and surface tension. Optimised melt compositions (OptiMelt) are expected to exhibit low formation temperatures and intermediate viscosities. In WP2, selected OptiMelt compositions will be used to produce clinkers with reduced firing temperatures and high reactivity, particularly through increased alite content. Further optimisation may be carried out based on experimental results. WP3 evaluates the performance of OptiMelt clinkers in combination with SCMs such as calcined clays and recycled concrete fines. This will allow us to assess the potential of melt optimisation for sustainable, energy-efficient, and highly reactive clinker systems. The project employs advanced techniques including high-temperature XRD, XRF, HT-microscopy, HT-rheometry, and thermodynamic modelling to systematically study the effects of dopants and A/F ratio on clinker phase formation. Microstructural analysis will be conducted using optical microscopy, SEM-EBSD-EDX, and µXRF. Reactivity will be assessed through hydration experiments and strength testing of mortar prisms. The collaboration with experts such as Alexander Pisch and Marcus Bannermann will support the refinement of thermodynamic databases. PhD students will benefit from access to complementary expertise and infrastructure across all three participating institutions.

• DFG Programme: Research Grants
• International Connection: Czech Republic
• Partner Organisation: Czech Science Foundation
• Cooperation Partner: Dr. Martin Bohac