Hydration mechanisms of Ba-doped ye’elimite: effect of Ba/Ca ratio on hydration behavior

Abstract

Than stoichiometric one. However, the hydration mechanism is not well understood, in particular for the effect of Ba/Ca ratio on hydration behavior. To shed light on this issue, high purity C4-xBxA3$ samples with designed element compositions (C4A3$, C3.5B0.5A3$, and C3BA3$) were prepared and their hydration processes were investigated. The results reveal that Ba-doped ye’elimite reacts faster than the stoichiometric ye’elimite. With the increase of Ba/Ca ratio, it can gradually increase the intensity of the initial peak, shorten the dormant period and reduce the total hydration heat. The phase composition evolution based on Rietveld/XRD method demonstrates that the dissolution rate of the C3.5B0.5A3$ and C3BA3$ are about 19% and 28% higher than that of C4A3$ in 6h. Moreover, the hydration sequences and main products varied significantly. The AFt is absent for the system with barium incorporation and AFm tends to be less with the increase of Ba/Ca ratio. This paper also proposes a new acceleration mechanism of Ba-doped ye’elimite. It is summarized as a higher rate of dissolution-precipitation reaction stemmed from higher ion precipitation of BaSO4 and a combination of extra surface for the nucleation sites provided by BaSO4.