Moudrakovski et al. . carried out a natural abundance high field Ca NMR study where they studied C-S-H with Ca/Si of 0.8, 1.2 and 1.5. The reported experimental Ca NMR spectra are in good agreement with the here presented theoretical findings. The experimental Ca NMR peak center of C-S-H with Ca/Si = 0.8 aligns well with the tobermorite 14 Å peak at ∼ 25 ppm , while for Ca/Si of 1.2 and 1.5 it is at > 30 ppm which agrees with the here reported DFT predicted chemical shift of mainlayer Ca (Table and Figure ).