@article{Glasser_Jappy_1992, title={Phase and density changes during the ’’conversión’’ reaction of high alumina cement}, volume={42}, url={https://materconstrucc.revistas.csic.es/index.php/materconstrucc/article/view/693}, DOI={10.3989/mc.1992.v42.i228.693}, abstractNote={The basis of the conversion reaction, in which high alumina cements develop hydrogarnet subsequent to their set, is weel-established and its mineralogical features accord with phase equilibrium relations in the CaO-Al<sub>2</sub>O<sub>3</sub>-H<sub>2</sub>O system. What is less well understood is the role of silica in the conversion. Silica may substitute into hydrogarnet, which has the formula Ca<sub>3</sub>Al<sub>2</sub>Si<sub>3-X</sub>O<sub>12-4x</sub>(OH)<sub>4x</sub>. Moreover the density of the hydrogarnet phase increases rapidly with the extent of silica substitution. Nomographs showing the variation of density and X-ray d spacing with composition are presented. Although HAC contains relatively little SiO<sub>2</sub>, examination of a high alumina cement warm cured at 85ºC and containing 2.46 wt% SiO<sub>2</sub>, shows that this hydrogarnet concentrates silica. Iron is, however, present mainly as amorphous hydrated iron oxide. Implications for cement proportioning to avoid conversion are discussed.}, number={228}, journal={Materiales de Construcción}, author={Glasser, F. P. and Jappy, T. G.}, year={1992}, month={Dec.}, pages={5–12} }