Effect of fineness and citric acid addition on the hydration of ye’elimite

Abstract

The first purpose of this article is to investigate the effect of fineness on the hydration of highly pure ye’elimite powders prepared by solid state reaction or by a chemical route. The second purpose is to examine the role of fineness on the hydration of model calcium sulfoaluminate cements (CSA) prepared by mixing our lab-made ye’elimite with gypsum. The last part concerns the effect of citric acid addition on hydration of a model cement. The main results are the following: (i) ettringite and hydrates formation can be accelerated by the presence of very fine ye’elimite powder in a CSA cement paste; (ii) the hydration rate of CSA model cement depends mainly on the dissolution rate of ye’elimite which can be delayed by the addition of citric acid in water; (iii) the surface of ye’elimite grains presents scarce etch pits when citric acid is present in the water, while the surface seems to be totally attacked with water.