A remastered external standard method applied to the quantification of early OPC hydration

A promising external standard method, first described by O'Connor [15], was used to determine the quantitative phase composition of a hydrating cement paste. On the basis of the data produced we can conclude that the method used is absolutely to be recommended for the examination of OPC pastes, since it displays many advantages in comparison to internal standard methods and other methods. No reaction of the phase alite could be detected during the initial and the induction periods of the cement hydration. Additionally it was found that the cement phases involved in the aluminate reaction (bassanite, gypsum, anhydrite and C3A) react successively. The changes detected in the phase composition of the OPC paste could be assigned to the different periods of OPC hydration.