A discussion of the paper “application of the scanning electron microscope to the study of the initial hydration of Portland cement paste” by D.M.R. Orr

✍ Scribed by S.L. Sarkar

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 32 KB
• Volume: 13
• Category: Article
• ISSN: 0008-8846
• DOI: 10.1016/0008-8846(83)90020-0

✦ Synopsis

In the above paper the author has emphasized the need for conductive coating of specimens by Au sputtering. It is worth noting that most modern electron-optical instruments, particularly SEMs are equipped with energy-dispersive spectrometers for microanalysis of specimens. Au sputtering of cementitious specimens generates a M peak of Au at 2.123 keV. Experience has shown the tail ends of the Au M peak tend to interfere with the Ks peaks of P and S at 2.015 and 2.308 KeV respectively. Since it is not unusual for cement and allied materials to contain both or either of these elements, it is advisable to coat the specimens with C rather than Au. The same desired level of conductivity may be obtained by this method of coating, particularly if a light layer of 'aquadag' is applied to the sides of the specimens. To minimize absorption of x-rays, the thickness of the C coating recommended is approximately 200A. *CCR I~3, 146-148 (1983).