Investigations of cementitious materials with low temperature SEM

Low temperature stages for scanning electron microscopy (SEM) were developed initially to avoid water loss from hydrated specimen when they are transformed to high vacuum conditions in the SEM. The preparation and shock freezing can be done within some minutes. Therefore it is possible by using this technique to investigate the water containing phases of hydration at very early stages of reaction. The use of the technique for investigation of cement (HAC, OPC) or cementitious systems will be shown at very early hydration stages with accelerating agent and without. The development of phases and distribution of phases can be demonstrated by using fractured frozen samples. The use of cryo-scanning electron microscopy is a very useful tool, but in all cases for interpretation of phenomena a combination of method is very useful in some cases indispensable for proper interpretations.