Silicon Substitution for Aluminum in Calcium Silicate Hydrates

Abstract

27 Al MAS and multiquantum (MQ) MASNMR (magic‐angle spinning nuclear magnetic resonance) spectroscopy were used to study the substitution of silicon by aluminum in calcium silicate hydrates (C‐S‐H), which are the main component of hydrated portland cement. Synthetic C‐S‐H samples were prepared, and their chemical stability was studied. Two‐dimensional 3Q‐MASNMR spectra revealed the chemical shift and quadrupolar parameters (delta iso , nu Q ) that labeled aluminum sites in the C‐S‐H. Tetrahedral aluminum was observed in the bridging and nonbridging sites of the silicate chains.