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  • Author or Editor: B. Pacewska x
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Abstract  

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.

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Abstract  

Investigations of physico-chemical properties of three kinds of fly ash and their influence on cement hydration were performed in this work. Thermal analysis, microcalorimetry, infrared absorption and others were used. It was confirmed that the kind of coal and combustion conditions essentially influence physico-chemical properties of fly ash and in consequence influence cement hydration. Investigated fly ashes show in cement system so-called pozzolanic activity. Fly ash from combustion of brown coal in fluidized furnace revealed better activity compared to other investigated ones. This work is an introduction to more extensive investigation of fly ash activation.

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Abstract  

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.

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The composition of a hydrated aluminium oxide was determined and the course of its thermal decomposition was investigated. The stages of the dissociation were established and all the solid and gaseous intermediates of the decomposition were identified. A correlation was observed between the peak temperatures for boehmite and the particle size and degree of crystallinity.

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Abstract  

The chemical corrosion and the mechanical strength were studied in cement mortars containing an additive of FBCC under conditions of long-term action of sodium sulphate solution or saturated brine. The observations have shown that saturated brine is a more aggressive agent, since it leaches Ca(OH)2 and contributes to the decomposition of the C-S-H phase thus worsening the compressive strength as compared with that of mortars kept in water. The addition of 20% FBCC inhibits the leaching process and counteracts the decrease of compressive strength in mortars kept in brine. On the other hand, sodium sulphate solution changes favourably the mortar microstructure, increases of the content of small pores and improves both the compressive and the flexural strengths, as compared with those of a mortar kept in water.

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Abstract  

In the present work an attempt was made to obtain mineral–carbon sorbents by thermal decompositon. The mineral matrix for the sorbents (aluminium hydroxide) was based on petrochemical waste stream containing considerable amounts of aluminium chloride. Reference tests were carried out with a model solution prepared with the use of analytical grade AlCl3. Atactic polypropylene and hydrocarbon mixtures obtained in the flotation of petrochemical waste waters were used as carbon-containing raw materials. The aim of this work was to determine the adsorption and structural characteristics of the complex sorbents and to check the possibility of evaluation of their hydrophobic-hydrophilic properties.

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Journal of Thermal Analysis and Calorimetry
Authors: M. Mioduska, B. Andruszkiewicz, B. Pacewska, and J. Pysiak
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Abstract  

In the present work an attempt was made to obtain mineral-carbon sorbents by thermal decomposition of solid waste materials containing, besides to mineral components, solid petroleum derivatives. The amount and the homogeneity of distribution of coal product formed in decomposition of organic matter on the surface of the mineral matrix, as well as the porous structure of the sorbents obtained depend largely on the conditions of calcination of the wastes used. The aim of this work was to find optimum conditions of the process. The sorptive properties of the obtained material were checked in the process of reduction of pollutants contained in industrial wastes.

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