Is there a future for ⁴³Ca nuclear magnetic resonance in cement science?

Calcium and silicon are critical components of cement. While 29Si nuclear magnetic resonance (NMR) is widely used in cement science, 43Ca NMR has received comparatively less attention given the experimental challenges associated with it. To investigate the potential of 43Ca NMR in cement research, a density functional theory study was carried out. The study focused on distinct calcium sites within the calcium silicate hydrate (C-S-H) structure. Four unique calcium sites were identified, each predicted to display distinct 43Ca chemical shifts due to differences in their local environments. These findings were used to generate theoretical 43Ca NMR spectra for C-S-H. Furthermore, theoretical 43Ca NMR spectra for the hydration reaction of triclinic tricalcium silicate were developed, illustrating the potential of 43Ca NMR for tracking the hydration process in multiphase systems.