RESEARCH OF BUILDING MATERIALS

STUDY OF CRYSTALLIZATION OF CALCIUM SULFATE DIHYDRATE THAT HAS POLYMER ADDITIVES

Vestnik MGSU 7/2012
  • Ustinova Yuliya Valer'evna - Moscow State University of Civil Engineering (MSUCE) +7 (499) 183-32-92, Moscow State University of Civil Engineering (MSUCE), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
  • Sivkov Sergey Pavlovich - D. Mendeleyev University of Chemical Technology of Russia (MUCTR) 8 (495) 496-92-38, D. Mendeleyev University of Chemical Technology of Russia (MUCTR), 20 Geroev Panfilovtsev str., Moscow, 125047, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
  • Aleksashin Valeriy Mikhaylovich - All- Russian Scientific Research Institute of Aviation Materials Candidate of Technical Sciences, Senior Researcher, +7 (499) 263-89-02, All- Russian Scientific Research Institute of Aviation Materials, 7 Radio St., Moscow, 105005, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Pages 130 - 135

Currently, functional additives represented by many classes of substances and compounds, including polymers of different origin, are widely used in the production of dry mixtures based on gypsum binders. However, the impact of these additives produced on the formation of calcium sulfate dihydrate (CaSO42H2O) crystals in the course of the hardening of gypsum binders, is not quite clear. Therefore, the research is aimed at the clarification of the processes of growth and formation of calcium sulfate dihydrate crystals in the presence of functional additives based on polymers of different origin. The research is composed of the following stages.
At the first stage, calcium sulfate dihydrate crystals were synthesized both in the pure form and with additives. The additives included super plasticizers based on sulfonated melamine-formaldehyde resin (SMF), methylcellulose (MC) and polymer powder based on copolymer of vinyl acetate, ethylene and vinyl chloride (VAEVC). At the second stage, X-ray analysis of the synthesized crystals was performed to identify potential patterns of influence produced by polymer additives onto the shape and size of calcium sulfate dihydrate crystals. At the third stage, thermal analysis and electron microscopy methods were applied to synthesized crystals.
The research suggests the following conclusions:
A. It is identified that additives based on polymers of different origin affect processes of crystallization, the size and shape of crystals.
B. The X-ray diffraction analysis has proven that molecules of polymer additives do not penetrate into the gypsum structure and the chemical composition of the product does not change.
C. Methods of thermal analysis have proven that the introduction of polymer additives does not produce any adverse impact on the stability of gypsum crystals, if exposed to temperature fluctuations.
D. The major impact produced onto crystallization is the one of the super plasticizer based on the sulfonated melamine-formaldehyde resin.

DOI: 10.22227/1997-0935.2012.7.130 - 135

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