This test method provides a relatively simple and reliable microscopical means of measuring the phase abundance of portland cement clinker (Note 1). Microscopical point counting provides a direct measure of the clinker phase composition in contrast to the calculated Bogue phase composition (Note 2).

Note 1-This test method utilizes a reflected light microscope. Related methods such as transmitted light microscopy, scanning electron microscopy, and automated imaging techniques may also be used for clinker analysis but are not presently included in this test method.

Note 2-This test method allows direct determination of the proportion of each individual phase in portland-cement clinker. This test method is intended to provide an alternative to the indirect estimation of phase proportion using the equations in Specification C 150 (footnote C in Table number 1 and footnote B in Table number 2).

This test method assumes the operator is qualified to operate a reflected light microscope and the required accessories, is able to correctly prepare polished sections and use necessary etchants, and is able to correctly identify the constituent phases.

This test method may be used as part of a quality control program in cement manufacturing as well as a troubleshooting tool. Microscopic characterization of clinker phases may also aid in correlating cement properties and cement performance in concrete, to the extent that properties and performance are a function of phase composition.