The production of inorganic-mineral bonded high-performance materials is not feasible without the use of organic admixtures. Parallel to the progressive development of these materials and the increasing number of starting materials used, among other things with regard to the substitution of_{CO2-intensive} Portland cement,[1,2] the importance of efficient admixtures leading to the realization of the desired material characteristics is also increasing. In the case of ultra-high performance concrete (UHPC), this includes compressive strength and durability, which can be significantly increased by an extremely dense matrix compared to conventional concrete. Central reasons for these property optimizations are the reduction of the water content of the concrete mix and the use of extremely fine, reactive fillers, such as silica fume, etc. Superplasticizers (FM) are required to give these mixes a workable consistency.[3] Furthermore, organic admixtures in the form of dispersible polymer powders (DP) are used in mineral adhesives such as tile adhesives. These polymers primarily influence the mechanical properties of the hardened adhesive mortar. For example, polymer-modified mortars are characterized by increased flexural strength and exhibit improved surface adhesion, which is conducive to their use as adhesives. In combination with fibrous reinforcement, dispersible polymer powders improve the bond between mineral matrix and steel fiber, which can further enhance the performance of mineral adhesives. For both application examples, the interaction of organic polymers with the mineral or metallic constituents of the concrete mix, which is influenced by many factors and is therefore highly complex, plays a decisive role.[4] Although the principles of action of both types of admixtures have been intensively investigated, research approaches for deeper understanding and further development are usually based on empirical and thus time-consuming trials. This can be remedied by a method from biology, whose usefulness for research in civil engineering is to be extended in the project applied for: Fluorescence microscopy. To detect polymer additives that cannot otherwise be detected by light microscopy, they are labeled with fluorescent markers. This method allows in-situ observation of the interaction of the additives with the various components of the binder glue. In this context, experimental parameters such as pH, ion concentration, additive content and character of the mineral phases play a crucial role and will be varied and systematically investigated. The method is validated by correlating the results of the fluorescence microscopic in-situ measurements with common analytical methods for adsorptivity and the macroscopic material properties of corresponding mortars. This new in-situ method allows studies of interactions of novel admixture-binder combinations whereby macroscopic properties can be predicted.

[1] N. Mahasenan, S. Smith, K. Humphreys in Greenhouse Gas Control Technologies - 6th International Conference (Ed.: J. G. Kaya), Pergamon, Oxford, 2003.

[2] M. S. Imbabi, C. Carrigan, S. McKenna, "Trends and developments in green cement and concrete technology," International Journal of Sustainable Built Environment 2012, 1, 194-216.

[3] M. Schmidt, E. Fehling, S. Fröhlich, J. Thiemicke (Eds.) Schriftenreihe Baustoffe und Massivbau. Sustainable construction with ultra-high strength concrete. Results of Priority Program 1182 funded by the German Research Foundation (DFG), kassel university press GmbH, Kassel, 2014.

[4] L. Ferrari, J. Kaufmann, F. Winnefeld, J. Plank, "Interaction of cement model systems withsuperplasticizers investigated by atomic force microscopy, zeta potential, and adsorptionmeasurements", Journal of Colloid and Interface Science 2010, 347, 15-24.