A promising mode of magnesia binder use in construction is dry building mixtures production. Depending on purpose they can be self-leveling, plastering, painting, primer, putty, etc. To produce those different binders, including magnesia one, can be used, depending on the desired aesthetic, environmental and anti-bacterial properties. It can be used in children's, medical, public institutions, and residential premises. The most preferable use for magnesia dry building mixes (MDBM) is as plaster for inner or outer buildings decoration. Plasters for external use have to be light, creating a ‘breathing’ coating that prevents thermal cold bridges formation, has high vapor permeability that can adjust to the equilibrium moisture content of magnesia design on the whole, has good adhesion to the coated surface and adequate frost resistance. Ordinary Portland cement and lime-silica binders are most often used for such products. Unlike materials based on these binders, magnesia products are characterized by rapid strength development under natural conditions. Therefore, the use of magnesia binders which allow obtaining high-strength, environmentally friendly and bioresistant materials for construction is particularly interesting.

Рис. 3. Рентгенограмма камня магнезиального вяжущего с добавкой никелевого шлака в количестве 20 % от массы вяжущего Рис. 4. Образцы «лепешки» с добавкой никелевого шлака 20 %

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Currently, magnesia materials are widespread in construction. However, the main problems of their mass use have remained unsolved due to a large number of factors, which result in the rise in their already high prime cost due to introduction of such process operations as crushing and milling of the introduced additives to increase their specific surface and hydraulic activity. Therefore, it is rather promising to search for such additives, which would contain active cations of metals and at the same time build in the structure of magnesium silicate hydrates and form insoluble minerals of the magnesia rock. The search for the additives led us to different sols, introduction of which is restricted to 1% of the weight of the binder, and which are able in such a small amount to increase the basic properties of the cement rock. The approbation of such additives and the evaluation of their influence on the properties, phase composition and structure of the magnesia binder are rather important. The article contains the results of evaluating the influence of the added iron hydroxide sol on hardening and curing of the magnesia paste, formation of the structure and properties of the magnesia rock. At carrying these researches out it has been determined that the iron hydroxide sol introduced into the composition of the magnesia-chloride binder in the amount of up to 1% of the weight of the binder is an efficient additive allowing to activate the development of the rock strength at an early age and to obtain the magnesia rock with the strength of 80 MPa and more, the water-resistance of no less than 0,8, and the hygroscopic property of no more than 2%.