INCREASING WATER RESISTANCE OF GYPSUM BINDERS

2018;
111-116
1
Lviv Polytechnic National University, Department of Building Production
2
Lviv Polytechnic National University, Department of building production
3
Lviv Polytechnic National University, Department of Building Production

One of the possible ways of restoring and further effective development of the construction industry with small investments is to expand the production and use of low-energy nonclinker binders. The use of gypsum and gypsum-cement-pozzolanic binder, obtained with the use of various waste and related products from other sectors of the national economy is perspective in this direction. It provides an increase of binders` required properties and improves their technical and economic indicators, solving to a certain extent the problems of ecology. In addition, the processes of gypsum hydration and dehydration, its widespread natural distribution, make it a sustainable resource, which can be recycled many times. This is a key element in the sustainable development. An analysis of literary sources concerning methods of water resistance increase of gypsum binders is represented in this article. It is shown that water resistance increase of gypsum products is achieved by reducing the solubility of gypsum; reduction of water-gypsum ratio; impregnation of products with substances that prevent penetration of water. Mineral additives, including industrial waste, are purposefully used for the purpose of modifying gypsum based compositions to increase strength, water resistance, durability, and chemical resistance of obtained materials and products. An important technological method, which provides an increase in the rate of reaction, is the activation of the binder with an increase in its specific surface. The paper presents the results of the study of admixtures and additions influence on the properties of gypsum binder, in particular on its water resistance. The influence of fly ash and Portland cement on the properties of gypsum has been established. It is shown that the greatest increase in strength and water resistance of gypsum is achieved due to mechanical activation of fly ash and
Portland cement in the composition of gypsum-cement-pozzolanic binder. The strength increase of gypsum-cement-pozzolanic binder on the basis of activated fly ash and Portland cement is 32 %, and the softening factor is 89 %.

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