A comparison between experimental and theoretical Ca/Si ratios in C–S–H and C–S(A)–H gels

Abstract

Abstract: The main component of the cement hydration, are both, the calcium silicate hydrate (C–S–H) and calcium silicate hydrate with Al (C–S(A)–H), whose composition is characterized by its calcium to silicon ratio (Ca/Si), which normally varies from 0.6 to 1.6. The theoretical Ca/Si ratios of the synthesized gels were compared with those of the experimental gels, which were determined by inductively coupled plasma atomic emission spectroscopy (ICP-OES). In addition, the microstructure of the gels was studied by spectroscopic techniques: infrared and Raman spectroscopy and nuclear magnetic resonance. By the double-decomposition method used in this work (1 day at 25 °C, inert atmosphere and pH = 12.3), only C–S–H and C–S(A)–H gels with a maximum Ca/Si ratio ranging from 0.8 to 1.0 were synthesized. However, the structures of the gels are slightly different as the Ca/Si ratio increases. [Figure not available: see fulltext.].