Gypsum-Containing Modified Materials

The use of gypsum-based materials in facade systems involves special preparation of the material for increasing the water resistance and frost resistance of gypsum products. The method of modifying the composition of the gypsum mixture with water-soluble polymers has a number of advantages. The introduction of organic additives into the mixture leads to the fact that gypsum, during hydration, creates a framework of crystalline aggregates of dihydrate, and the resin, when cured, forms a continuous polymer matrix. The purpose of this experiment was to identify the effectiveness of modifying mineral compositions based on gypsum binder with melamine-formaldehyde resin and other additives; to clarify the mechanism of curing melamine-formaldehyde resin (MFS) in polymer-mineral materials; to study the effect of modifying additives on the hydration process of gypsum binder. The study of the properties of the material was carried out using X-ray phase analysis, complex thermal analysis. The structure of the samples was studied using an electron microscope. The content of water-soluble substances was determined by boiling pre-crushed samples. After boiling, the solution was filtered through a “blue ribbon” filter and evaporated in porcelain cups in a water bath. The content of melamine-formaldehyde resin in water extracts was determined using a UV spectrophotometer. The ratio of two-water and semi-water gypsum in the samples was calculated using the Hermans and Weidinger method. As a result of the research, the possibility of using melamine – formaldehyde resin for the production of water-and weather-resistant polymers is justified. It is established that the presence of fluorosilicic acid makes it possible to obtain a degree of curing of the resin similar to the heat-treated material. The resin is almost completely retained in the polymer-mineral material due to the formation of a common spatial structure. Modification of the gypsum binder with melamine-formaldehyde resin, as well as the introduction of a superplassifier, leads to a decrease in the degree of gypsum hydration. Phosphogypsum helps to slow down the process of hydration of the gypsum binder and reduce the degree of its hydration during heat treatment.

I.V. BESSONOV¹, Сandidate of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.);
A.D. ZHUKOV^1,2, Сandidate of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.),
E.A. GORBUNOVA^1,2, Engineer (This email address is being protected from spambots. You need JavaScript enabled to view it.)

¹ Research Institute of Building Physics, Russian Academy of Architecture and Construction Sciences (21, Lokomotivniy Driveway, Moscow, 127238, Russian Federation)
² National Research Moscow State University of Civil Engineering (26, Yaroslavskoe Highway, Moscow, 129337, Russian Federation)

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