INFLUENCE OF POLYMERIC ADDITIVES ON CRYSTALLIZATION OF CALCIUM SULPHATE DIHYDRATE

• Main Author: Ustinova Yulia Valer’evna
• Format: Article
• Language: English
• Published: Moscow State University of Civil Engineering (MGSU) 2013-04-01
• Series: Stroitel’stvo: Nauka i Obrazovanie
• Subjects: calcium sulfate dihydrate; plasters; functional additives; dry mixes; super softener based on melamine-formaldehyde resins; methylcellulose; electron microscopy; X-ray structural analysis
• Online Access: http://nso-journal.ru/public/journals/1/issues/2013/02/3.pdf

Currently, functional additives are widely spread in the production of inorganic dry mixtures. However, their impact on the microstructure of products, generated in the process of hardening of inorganic binders, is understudied. In this context, the goal of the work is the study of calcium sulfate dihydrate (CaSO •2H O) crystallization. Super plasticizer based on sulfonated melamine-formaldehyde resin, methylcellulose and vinyl acetate, ethylene and vinyl chloride copolymer powder were selected for studies. First, pure calcium sulfate dihydrate crystals were synthesized. Then, synthesized calcium sulfate dihydrate crystals were exposed to the X-ray analysis to determine the nature of influence of polymer additives on the shape and dimensions of crystals. Possible combinations of simple forms of CaSO •2H O were identified by the X-ray analysis and the special software. Electronic microscopy analysis was performed to validate models of calcium sulfate dihydrate crystals. All plasticizers influence the crystallization of calcium sulfate dihydrate. The influence of additives on the shape and dimensions of crystals of calcium sulfate dihydrate can be explained by the fact that molecules of sulfonated melamine-formaldehyde resins, methylcellulose, and copolymers of vinyl acetate, ethylene and vinyl chloride are absorbed by crystal faces. It is proven that the method of X-ray analysis can be used to predict the shape and habitus of crystals.