Preparation of flat-polished specimens of slag-blended cement paste for backscattered electron imaging

Scanning electron microscopy (SEM)-backscattered electron imaging and analysis (BSE-IA) is invaluable in blended cement research owing to its quantitative analysis qualities. For BSE-IA, flat-polished specimens without any artefacts are essential. However, preparation procedures of polished specimens are indefinite and are not stated in detail for cement paste, and no reports about it for slag-blended cement paste exist in published works. In this paper, excellent flat-polished specimens of slag-blended cement paste were prepared, and several factors influencing specimen quality were studied. Based on the authors' research, appropriate operations were suggested for the specimens to achieve high epoxy intrusion depth – that is, apply coarse emery papers for dry pre-grinding, let specimens stay under vacuum of 0·1 bar for at least 2 min before epoxy feeding, release the vacuum after epoxy feeding immediately. Moreover, it was found that increasing grinding force was effective in improving the planeness level of the polished surfaces, and 30 N was needed for slag-blended cement paste specimens to avoid obvious relief and altitude difference.