Scanning electron microscopy imaging of hydraulic cement microstructure

Use of the scanning electron microscope (SEM) with X-ray microanalysis allows study of clinker and cements; permitting measuring bulk phase abundance and surface areas of the phases, as well as bulk chemistry of constituent phases can be carried out. Direct imaging of hydraulic cements by SEM yields a more complete picture of both bulk and surface phase compositions. Mass percentages obtained by SEM imaging are in good agreement with percentages based upon QXRD and may differ significantly from those estimated by the Bogue calculations. The finer-grained phases (gypsum, tricalcium aluminate, and ferrite) show much higher surface areas per unit mass than the coarser-grained phases such as alite and belite. Such data are being applied to develop better relationships between the cement material properties and performance properties and to provide starting images for a cement hydration simulation model being developed at NIST. @ 2004 Elsevier Ltd. All rights reserved.