Low-temperature scanning electron microscopy

This research involves an in-depth description of the morphology of ice as it appears in the entrained air voids of hydrated cement paste. The focus of this analysis is micrographs generated with the use of the low-temperature scanning electron microscope (LTSEM). The LTSEM allows for the imaging of frozen, hydrated cement paste specimens. With LTSEM techniques, specimens can be fractured under vacuum at low temperatures, allowing the imaging of the interior of the specimen, where the original ice morphology remains unaffected by the specimen preparation techniques. The LTSEM has advantages over traditional scanning electron microscopes, which do not allow for imaging of ice as it naturally occurs in the air voids, and over optical microscopic techniques, which have significantly lower resolution than the LTSEM. The specimens can also be slowly warmed while being imaged in the LTSEM, which allows the same locations to be imaged before and after the sublimation of any ice.

References:

Monteiro P. J. M., Bastacky, S. J. and Hayes, T. L. "Low-Temperature Scanning Electron Microscope Analysis of the Portland Cement Paste Early Hydration." Cement and Concrete Research, Vol. 15, no. 4, 1985, pp. 687-693.

D.J. Corr , P.J.M. Monteiro and J. Bastacky, Microscopic Characterization of Ice Morphology in Entrained Air Voids", Microscopic Characterization of Ice Morphology in Entrained Air Voids", ACI Materials Journal (in press).