RESEARCH OF MODIFIED GYPSUM BINDERS PROPERTIES

In the article the analysis of literary sources concerning methods of gypsum binders modification is shown. It is shown that today more and more attention is paid on the ecology of production and the maximum efficiency of the use of natural resources, therefore the development of non-klinker binders, such as anhydrite and gypsum, is relevant. Building gypsum has become widely used in the industry of production rapid hardening plastic masses which are easily aligned and used in the installation of floor, ceiling, wall coverings, if necessary, the laying of joints, cracks and irregularities, in the manufacture of artificial gypsum stone. Expansion of the application of gypsum binders requires improvement of physical and mechanical characteristics of gypsum, in particular through the use of mineral and chemical admixtures, which allow to optimize the formation of the structure of gypsum stone and to obtain effective composites with a stable structure. The paper describes the characteristics of the materials used in conducting experimental studies. The results of the investigation of influence of chemical admixtures on the basis of polycarboxylates on the properties of gypsum binder are presented. It has been found that the use ofMaster Glenium® ACE 450, Glenium 430, MС-Power Flow 2695 as admixtures provides a water-reducing effect in the range of 20–36% with admixture consumption of 1 wt.%. It is shown the influence of admixtures on setting time of gypsum binder and the strength and water resistance of gypsum stone. The strength of gypsum stone after full drying increases by more than 2 times, and for gypsum stone containing 1 mass. % of Glenium 430 is 51,6 MPa, while the stone without additives is characterized by a strength of 26 MPa. By the researches of the processes of structure formation have been established that in the presence of admixtures of polycarboxylate type there is an adsorption modification of two-hull gypsum crystals with the formation of more ordered and denser structure of gypsum stone, which affects the physical and mechanical as well as constructional and technical properties of the material.

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