Progress in building materials analysis (Part 2)

Summary: By means of modern electron microscopy and preparation technologies it  could be proved without doubt that the temporary syngenite formation during the early hydration of OPC with a high content of potassium sulphates is not an ESEM artefact. It can be derived from the microscopic investigations that the C-S-H phases occurring during the hydration process of OPC or C3S in the outer hydration rim always show the same needle-like habit and they have a crystalline nature. These C-S-H phases are very sensitive to radiation damage. Furthermore some applications of the integrated EDS-EBSD system for phase identification and orientation mapping for the subgrain crystal size determination are presented.

4 Results and discussion

In the following some examples are described relating to the manifold microscopic and analytical capabilities of the FEI Nova NanoSEM in combination with high-pressure cryo-preparation techniques. These methods are especially useful to answer fundamental questions on cement chemistry.

 

Are the C-S-H phases crystalline which are
formed during the OPC hydration?

The C-S-H phases formed during the hydration process at ordinary temperatures and for realistic water/cement ratios of C2S, C3S and OPC always appear in the same needle-like morphology when ESEM-FEG and NanoSEM...

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