POSSIBILITIES OF SPECIAL CEMENTS IN CERAMIC APPLICATIONS

About 25 years ago, the only way to have confinement material for high temperature applications was to prepare a ceramic by sintering or fus ion at high temperature. A new technology came, with the production of Low Cement Castables. This new product was obtained by a careful choi ce of the granulometry of the aggregates, an optimization of the deflo culation of fine particles, including the cement (Calcium Aluminate Ce ment) and the addition of silica fume. Silica fume brought two improve ments: a fluidifying effect, due partly to the low sensitivity of visc osity to pH, and partly to the geometric effect of the nicely spherica l particle. a chemical effect, brought by the reaction of silica and C alcium Aluminate Cement to give a coherent zeolithic structure, throug h which water could escape during the first firing. From a ceramist po int of view, it is interesting to understand how this components, near ly colloidal system mixed in water can be heated up to ceramization wi thout any noticeable change in mechanical characteristics and shrinkag e. From a more practical point of view, it is also interesting to real ize that some characteristics, usually attributed only to ceramics, al so apply with low cement castables technology: high compressive streng th, flexural strength, corrosion resistance, abrasion resistance, impa ct resistance.