Crystal structure refinement and hydration behaviour of 3CaO·SiO2 solid solutions with MgO, Al2O3 and Fe2O3

In this paper, analytical evidence on crystal structure and hydration behaviour of 3CaO·SiO2 (C3S) solid solutions with MgO, Al2O3 and Fe2O3 is presented. Samples were prepared using an innovative sol–gel process as precursor. The Rietveld refinements of XRDs show significant changes in the crystal structures for C3S solid solutions with MgO and Al2O3, but only small changes for Fe2O3. Low concentrations of MgO do not change the hydration of C3S, but 1.4 wt.% increases the reactivity after some days. With Al2O3 the initial and long-term hydration is activated, but the main reaction of C3S decreases. Fe2O3 retards the hydration for several days, the long-term reaction is not affected or even activated. Altogether changes in hydration activity are more dominated by the type of oxide than by the height of changes in lattice parameters. The results can help to interpret the reactivity of different Portland cements and improve the quality control of the cement production.