Twittern

Progress in building materials analysis (Part 2)

• 15 C₃S after 18 h hydration time: a) Helix...

• 16 Cryo-SEM: a) high content of K-sulfate OPC – 9...

• 17 UHPC matrix with reacted silica fume particles...

• 18 UHPC matrix with spherical shaped silica fume...

• 19 OIM analysis of a strained quartz: subgrains...

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• Reaction products of blast furnace slag (left) and...

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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.

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.

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...