Analysis of Phases in Cement Paste using Backscattered Electron Images, Methanol Adsorption and Thermogravimetric Analysis

Abstract

In backscattered electron (bse) images of polished cement sections, anhydrous material, calcium hydroxide, other hydration products (mainly C-S-H) and porosity can be distinguished on the basis of their grey level in the image. Using an image analyzer connected directly to the SEM, it is possible to resolve these four components and so measure their relative proportions and distributions. The effects of magnification and the number of fields measured on the accuracy of bse image analysis are examined. The volume fractions of anhydrous material, porosity and calcium hydroxide derived from bse image analysis are compared with those obtained by other techniques and good correlation was found for the measurement of anhydrous material and porosity.

Evaluation of capillary pore size characteristics in high-strength concrete at early ages

“…However, the errors of coarse capillary pores are quite small. It seems that the variations of those measured values are almost comparable to the results of Scrivener et al [4]. Therefore, the difference in phase constituents between concretes with and without silica fume (Fig.3) is significant even if the variation of unhydrated cement (i.e.…”

“…However, as mentioned above, the volume of coarse pores quantified by the imaging may play a significant role in various properties of concrete. Furthermore, area fractions of unhydrated cement particles evaluated by the imaging method can be related to the degree of hydration which is an important parameter to characterize the hydration process [4,5]. Therefore, the SEM-BSE imaging technique can be expected to provide useful information for interpreting the behavior of concrete in terms of the evolution of microstructure at early ages.…”

Analysis of cement pastes and mortars by a combination of backscatter-based SEM image analysis and calculations based on the Powers model

“…The degree of hydration of cement (α) was calculated by Equation (1) [6,11]. It was confirmed in advance that the volume fraction of cement in a mixture of cement and epoxy resin was closely equal to the volume fraction determined by the image analysis.…”

“…In order to avoid influences of interfacial transition zones around fine aggregate particles on results, regions of interest for acquiring images in mortars were taken sufficiently away from surfaces of sand particles. Taking account of statistical variations in the results of image analysis, ten fields in each specimen were randomly chosen and analyzed [6,10]. Each BSE image (e.g.…”

“…porosity gradients in concretes were made by Scrivener and Pratt [5,6]. At early stages in the development of this technique, the area fraction of measurable image parameters was a key quantity to understand features of microstructure in concrete.…”