Hydration of cement slurry in the presence of spent cracking catalyst

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.