Yaroslav Yakymechko, Roman Jaskulski and Iryna Lutsyuk
The article presents new methods of improving technological properties of quicklime as a binder. The sources of high hydraulic activity of calcium oxide were investigated and discussed. It was shown that during CaO hydration a layered structure with a smaller number of symmetry elements is formed and the molar volume increases, which leads to system growth and accelerates the hydration reaction. The use of additives based on phosphoric, boric and sulphuric acids and their salts changes the conditions of the individual stages of the CaO hydration process, thus increasing the strength development of lime stone by 1.5 - 2.5 times. It was shown that in the presence of SO4 2- anions, portlandite crystallises mainly in the form of thin hexagonal plates, which influence the mechanism of development of lime stone flexural strength. On the basis of the obtained results, binders containing quicklime, hydraulically active component and sulphates were prepared. It was found that the introduction of quicklime into building plaster prolongs the setting time, while hydration hardening СаО was provided. Such mixed gypsum-based binders with the addition of quicklime are characterized by high water resistance and compression strength typical for gypsum stone.
Quicklime, portlandite, hydration hardening, gypsum, hydration.