The physicochemical properties of spent fluidized bed cracking catalyst and its influence on hydration process of cement slurry
were studied. The samples were cement slurries prepared with water/solid=0.5 and additions of used catalyst amounted to 0,
5, 10, 15, 20 and 25%with resp. to the solid. After definite time they were subjected to thermogravimetric analysis (TG, DTG,
DTA) and, in order to determine the progress of reaction with water, the heat of hydration was measured by means of isotherm
calorimetry. The studies disclosed that the spent cracking catalyst is not merely an inactive filler in cement slurries, but
it modifies the course of the hydration process. The spent catalyst is a pozzolana additive and its presence leads to a decrease
of calcium hydroxide contents in the system. The spent catalyst affect on the heat of cement hydration. Small amounts additive
accelerate the process of binding.
The influence of spent catalyst from catalytic cracking in fluidized bed on the hydration process of cement and the properties
of cement mortars were studied. The spent catalyst was used as an additive to cement in the mortars (10 and 20% of cement).
The samples of mortars kept in water for28 days, then they were placed in sulfate and chloride media for 2 months (the control
samples were kept in water for 3 months). After this time they were subjected to bending strength and compressive strength
determinations. Thermogravimetric and infrared absorption studies were performed and capillary elevation, capability of binding
heavy metals, and changes in mass and apparent density were determined too. The studies disclosed the pozzolana nature of
spent catalyst and its influence on cement mortars being in contact with corrosive media.