Project summary

Cement remains the most widely produced building material worldwide, and its energy-intensive production contributes to approximately 7-8% of anthropogenic CO₂ emissions. Strategies to reduce these emissions are necessary to achieve climate neutrality. The most straightforward approach for this is the use of sufficiently reactive supplementary cementitious materials (SCMs). Therefore, the research project "Artificial Intelligence for smart design and testing of cement and concrete" (AICC) investigates the reactivity of SCMs using fully amorphous, chemically defined model glasses. To minimize the effect of various physical parameters, the model SCMs are synthesized as amorphous glasses at high temperature and milled to a comparable specific surface area. A comprehensive physicochemical characterization is performed – including X-ray diffraction (XRD) to determine crystallinity, helium pycnometry to analyze density, Blaine and BET surface area determination, laser granulometry for particle size distribution, and structural analysis using Fourier-transform infrared spectroscopy (FTIR) and ²⁹Si/²⁷Al nuclear magnetic resonance (NMR), which is compared with theoretical considerations such as NBO/T. Reactivity is initially assessed indirectly: The established R³ test (XRD, thermogravimetry (TGA), and isothermal calorimetry) is used, and the total heat release in this cement model system is correlated with the SCM reactivity. In complementary cement paste experiments, the phase assemblage was analyzed using XRD and TGA after specific hydration times. These cement pastes will also be examined by electron microscopy to determine the degree of reaction after different hydration times, allowing direct conclusions about the reactivity. Since this method is very time-consuming and user-dependent, an AI-supported tool will be developed in collaboration with the Chair of Computer Vision & Artificial Intelligence group to automate the evaluation. The overall goal of the project is to investigate model SCMs with different chemical compositions in order to assess the impact of various metal oxides on reactivity, which could ultimately facilitate the search for new SCMs.