Investigation of Three-Dimensional Microstructure of Tricalcium Silicate (C(3)S) by Electron Microscopy

A serial block-face scanning electron microscopy (SBFSEM) system, composed of a scanning electron microscope (SEM) and an ultra-microtome installed within the SEM vacuum chamber, has been used to characterize the three-dimensional (3D) microstructure of tricalcium silicate (C(3)S) grains embedded in epoxy resin. A selection of C(3)S grains were segmented and rendered with 3D-image processing software, which allowed the C(3)S grains to be clearly visualized and enabled statistically quantitative analysis. The results show that about 5% of the C(3)S grains have volumes larger than 1 μm(3) and the average volume of the grains is 25 μm(3). Pores can also be clearly seen in the biggest C(3)S grain, the volume of which is 3.6 × 10(4) μm(3), and the mean volume and total volume of all the pores within this grain are 4.8 μm(3) and 3.0 × 10(3) μm(3), respectively. The reported work provides a new approach for the characterization of the 3D spatial structure of raw C(3)S materials, and the resulting 3D structure of the raw C(3)S is important for further systematic research on the relationships between the spatial microstructure and the hydration kinetics of C(3)S and other cement minerals.