Characterisation of carbonated materials using SEM-EBSD

Mineral carbonation is a promising strategy for reducing CO₂ emissions. In particular, the formation of calcium carbonate can lead to solid structures comparable to natural limestone reservoirs, which can develop significant mechanical strength. A fundamental understanding of the relationship between calcium carbonate precipitation and microstructure formation is essential for the design of carbonatable binders. In this study, carbonated C₂S-based binders are characterised using electron backscatter diffraction (EBSD) in the scanning electron microscope (SEM). A key challenge for EBSD analysis lies in sample preparation, therefore argon broad ion beam (BIB) polishing was compared with vibrational polishing. The results indicate that vibrational polishing is more effective in producing a smooth surface that yields EBSD patterns of calcite with high contrast. BIB polishing is advantageous to analyse the residual y-C₂S. EBSD is used to measure crystallite size of calcite. This work serves as basis to compare calcite crystallisation obtained from different carbonation routes.