| Abstract [eng] |
The aim of the research project is to synthesize a pozzolanic additive for cement from mica clay and spent catalytic cracking catalyst. It was investigated that the used catalytic cracking catalyst contains mainly oxides of SiO2 (45.3 %) and Al2O3 (44.4 %), 40% of the catalyst particles are 48 μm in diameter, the catalyst belongs to the group of zeolites, the predominant mineral is faujasite. The catalyst was found to contain a small amount of water and compounds that decompose at 30 - 900 ° C. As the catalyst contains a large amount of Al2O3 oxide and the mica clay contains Al2O3 several times less, it was decided to add a catalyst to the mica clay and thus increase the amount of alumina in the overall system. A heat treatment method was chosen to activate the pozzolanic additive. The pozzolanic additive is heat-treated at different temperatures up to 900 °C, because according to the literature, increasing the temperature to <1000 °C increases the amount of amorphous phase and consequently improves the pozzolanic activity. During the work it was determined that the more catalyst is added to the clay, the higher the pozzolanic activity of the synthesized additive, therefore it was decided to synthesize the additive from 40 % of the used catalytic cracking catalyst and 60 % of the mica clay. The highest pozzolanic activity (495.36 CaO/g) was of additive containing 40 % fluid catalytic cracking catalyst and 60 % mica clay and it was found to be 43.6 % higher than that of the additive from only mica clay calcinated at 900 °C. The samples were replaced with 5 – 15 % cement pozzolanic additive, calcinated at 600, 700, 800, 900 °C, the samples were hydrated for 7, 28, 84 days. After 7 days of hydration, the pozzolanic additive increased the strength of the samples to 27 % compared to the samples without the additive. Based on XRD and DSC-TG data, it has been shown that after 28 days of hydration, pozzolanic reactions take place in the samples with the additive, which reduces the intensities and weight loss of Portlandite curves and leads to an increase in compressive strength. It was found that increasing the amount of the additive from 5 to 10 % increases the value of compressive strength, because the pozzolanic additive reacts more intensively, the higher its amount reacts. |
