PROBLEMS AND PROSPECTS OF USING ALUMINATE CEMENTS FOR THE PRODUCTION OF UNFORMED REFRACTORIES

The hydration process of zirconium-containing high-alumina cements (85-90 wt.% CA2) with additives of ZrO2 and AlOCl introduced at the clinker firing stage was studied. Based on the results of the analysis of the composition of the liquid phase and solid phases, it was established that at an early age, modified cements hydrate more slowly, and then this process accelerates and after 21 days they are ahead of the control cement VGC-70 in terms of hydration. The hydration products of zirconium-containing cement by 28 days contain metastable hydroaluminates CAH10, C2AH8, aluminum and zirconium hydroxides, whereas for the control high-alumina cement, C3AH6, C2AH8 and Al(OH)3 are more characteristic. The simultaneous presence of zirconium- and chloride-containing phases significantly reduces the rate of hydration and at the same time promotes the formation of a more uniform dense structure of cement stone.