Mineralogical causes of low strengths in test mortar prisms or cubes at the cement plant can be investigated microscopically using a combination of optical microscopy and scanning electron microscopy (SEM).

Polished sections are typically used; those for optical microscopy are etched (eg: with nital) to enable the clinker phases to be differentiated.

These microscopic techniques indicate the burning conditions in the kiln, raw meal homogeneity (or lack of), and the compositions of the clinker minerals determined. By comparing "suspect" and "normal" samples of clinker or cement, likely causes of poor strength development can be assessed.


Problems with concrete and mortar can often be identified microscopically, either using optical microscopy to examine thin sections of material, or SEM to examine polished sections.

Microscopy can identify issues related to strength, colour and deterioration in either recent or older concretes. Eg: degree of cement hydration, how well the mix components have dispersed and segregation and bleeding can all affect strength. Colour can be influenced by pigment dispersal or efflorescence or in the case of decorative concrete, the effects of bird lime or attempts at cleaning. Causes of deterioration including alkali-silica reaction and sulphate attack can be identified.

We also examine historical cementitious materials including Roman, mediaeval and 15th-19th century mortars and concretes.


Our sister website, www.understanding-cement.com, has much information on cement manufacturing, cement hydration and problems with concrete, with an emphasis on cement science.

Our publication "Understanding Cement" is available in both ebook (pdf) and printed book format from the UC website, as is the printed book "Scanning Electron Microscopy of Cement and Concrete".

We can also offer our "Understanding Cement" one-day seminar.