SI-29 MAS NMR-STUDY OF DICALCIUM SILICATE - THE STRUCTURAL INFLUENCE OF SULFATE AND ALUMINA STABILIZERS

The effect on beta-C2S of two stabilizing agents, calcium sulfate and alumina, has been investigated using high-resolution Si-29 solid state NMR spectroscopy. Syntheses mere achieved via the gel route, wet or d ry processes, Room-temperature NMR spectra characteristics mere analyz ed as a function of the sintering temperature, The incorporation of Al 3+ and S6+ ions, which finds expression in a noticeable line broadenin g, is shown to be effective above 1200 degrees C. The Si-29 chemical s hift is unchanged upon doping, suggesting a mean SiO4 tetrahedra geome try identical to that in pure beta-C2S General trends on the structure adopted by C2S upon Al3+ and S6+ doping are also discussed.