Study of calcium silicate hydrates by solid state high resolution 29Si nuclear magnetic resonance

Abstract

Synthetic calcium silicate hydrates were hydrothermally prepared at temperatures between 100 and 200°C. Preparations of tobermorite, xonotlite, hillebrandite, gyrolite, kilchoanite, calciochondrodite, α-dicalcium silicate hydrate and tricalcium silicate hydrate were characterized by X-ray diffraction, scanning electron microscopy and infra-red spectroscopy. The products were examined by high resolution solid state 29Si nuclear magnetic resonance (NMR) spectroscopy. Spectra for tobermorite, xonotlite, hillebrandite and tricalcium silicate hydrate have previously been reported, hut spectra for gyrolite, kilchoanite, calciochondrodite and α-dicalcium silicate hydrate are reported for the first time. NM R spectra reveal information about phase structure suggesting that some of the postulated crystal structures are incorrect. NMR spectroscopy shows promise as a means of identifying constituent phases of the silicate matrix in autoclaved cement pastes.