Experimental and Numerical Analysis on the Hydration of C3S/C3A Systems

The aim of this thesis is to gather better understanding and the involved reaction mechanism in the early age hydration of portland cement systems. As alite (C3S) and aluminates (C3A) are the major phases which would affect the early age reaction, an in-depth study is carried out on the synthetic phases of C3S, C3A and polyphase model systems of C3S and C3A. From the research it was found that C3S hydration is controlled by a nucleation and growth based mechanism, which is dependent on the internal surface area of C-S-H. In the case of C3A, it has been found out that it is controlled by a dissolution mechanism. It has also been found out that the w/c has a significant effect on the overall degree of hydration of C3A, while there is only marginal effect on the degree of hydration of C3S. In polyphase C3S-C3A model systems, it was found that the hydration of C3A has a major effect on controlling the reaction kinetics of C3S.