Chemical equilibria between C-S-H and ettringite, at 20 and 85 °C

Mixes of C-S-H and ettringite were synthesized in suspension systems and their equilibria were studied at 20 and 85 degrees C. Concentrations in solution (calcium, sulfate, aluminium) were measured and the mineralogical state of the systems was studied by means of X-ray diffraction. The equilibria between C-S-H and ettringite are described. The relative importance of sulfate bound to the C-S-H is evaluated. The kinetics of ettringite reprecipitation from a "C-S-H-ettringite" system at 85 degrees C placed at 20 degrees C are also evaluated. (c) 2007 Elsevier Ltd. All rights reserved.