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.