Early Hydration of Tetracalcium Aluminoferrite in Gypsum and Lime‐Gypsum Solutions

Based on product compositions and on the compositional changes occurring in the aqueous phase, a mechanism for the early hydration of C4AF in solutions containing gypsum or lime and gypsum is suggested. According to this mechanism, early formation of AFt is preceded by the formation of alumina gel or C2AH8. Early AFt formation occurs through solution, and the early AFt product contains little or no iron. The solution chemistry also suggests that an amorphous, iron-rich gel forms and that calcium is associated with this gel.