Molecular mechanisms of mechanical and chemical corrosion on cement-bound materials

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Within the framework of this project, the molecular mechanisms of mechanical and chemical corrosion on cement-bound materials will be investigated. For this purpose, an ultra-thin calcium silicate hydrate phase (C-S-H phase, as a model for a cement layer) is synthesized on Si wafers and the Si wafers are bent in the elastic range. The resulting stress (in the C-S-H phase) can be compared with a uniaxial length change in a tensile testing machine. Under stress, various exchange and transport processes (as a model for chemical corrosion) at the C-S-H phase interface are investigated using infrared spectroscopy. Here, selected infrared sensor molecules are used which adsorb particularly on defects on the surfaces. In addition, parameter-free calculations are carried out using the density-functional theory (DFT), since they can be ideally matched with the experimental model substrates. The new findings on mechanical and chemical corrosion will provide opportunities to improve the synthesis of the C-S-H phases in order to make them mechanically and chemically more stress-resistant.