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Cementitious materials represent the most used materials in the construction industry. Their strong heterogeneity and multiscale microstructure make the study of the mechanical properties and the in-service behaviour very challenging: new techniques are required by industrial research to better investigate these aspects. In this work a novel technique based on statistical nanoindentation is exploited to obtain results about the microstructure build-up and the mechanical properties. An innovative high-speed nanoindentation method is here combined and compared with a standard nanoindentation procedure in order to get highly consistent statistical results. Combining the high-speed nanoindentation, the statistical deconvolution and SEM/EDS investigations, the main phases present in the tested hydrated cement paste have been characterized. High-resolution maps of the mechanical properties are in good agreement with SEM-EDS results. The evolution of the mechanical properties has been tested over the time and in particular after 1, 3, 5, 7, 14 and 28 days of hydration. It was found that the nano-mechanical properties were almost constant during the hydration time and the evolution of the bulk mechanical resistance properties of the cement paste is found to be due to a variation of the volume proportions between the three principal phases (low-density, high-density and ultra-high-density C–S–H). Keywords: Cement, Nanoindentation, High-speed, Statistical, Mapping, Packing density

Composite ZrB2-SiC materials offer well known resistance to ablation at high temperature. An inert plasma spraying technique was used to manufacture composite ZrB2-SiC as potential thermal protection systems for composite based substrates. Due to the rapid solidification experienced by sprayed droplets, amorphous and/or nanostructured phases can be formed; advanced characterization techniques are therefore required in order to collect all the necessary data for process/product optimisation. In addition, silicon carbide, selected for its contribution to the oxidation resistance of the ceramic coating, is well known to be considered as a non sprayable material, due to the lack of a stable liquid phase. In this paper, two issues are investigated: the first is the use of advanced characterization techniques, such as high resolution scanning and transmission electron microscopy, for microstructural analysis of plasma sprayed coatings. The second is the evaluation of possible implications of rapid solidification processes in composite systems for which at least one liquid phase is not stable, but, at the same time, the development of eutectic-like structures results in the formation of nanostructured stable solid phases.