The influence of spent catalyst from catalytic cracking in fluidized bed (FCC) on the hydration of two kinds of calcium aluminate cements (of about 40 and 70% content of alumina) was studied. Cement pastes were prepared with constant ratio of water/binder = 0.5 and with content of 0, 5 and 25% mass of addition as replacement of cement. The samples were stored at room temperature. Thermal analysis (TG, DTG), infrared absorption (FTIR) and X-ray diffraction methods were applied to investigate changes in various periods of hydration (up to 150 days). The compressive strength of cement mortars was also examined. On the basis of presented results it was affirmed that in studied conditions spent FCC catalyst is a reactive addition in calcium aluminate cement (CAC) pastes, which probably can create a new phase type C-A-S-H. It may be an interesting alternative for limitation of the negative phenomenon of conversion of aluminate hydrates, although the degree of the influence of the mineral additive depends on the composition of CAC and of the quantity of the used waste.
Adding sodium tripolyphosphate as a mix component of a medium-cement refractory castable is shown to modify some of the castable's properties. A correlation has been established between the concentration of sodium tripolyphosphate additive and the electrical conductivity (EC) of a suspension compositionally close to the castable, which makes it possible to follow the kinetics of heat release in the paste using EC measurements.A relationship between the Na tripolyphosphate concentration and the setting time of the paste is discussed.
The potential use of a porous (~20%) chamotte filler in a low-cement castable with an integrated matrix is considered. Results of a study of the properties of conventional, medium-cement, and low-cement castables are presented.
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