PRESSED GYPSUM AND MAGNESITE COMPOSITES OF INCREASED RESISTANCE TO ALTERNATE WETTING AND DRYING
The results of studies aimed at the possibility of increasing the water and air resistance of pressed small - piece gypsum and magnesite products by introducing modifying fillers into the composition of molding mixtures, which are secondary resources. In the studied compositions based on a low - grade gypsum binder, a complex modifier was used consisting of a carbonate - containing sludge from the chemical purification of thermal power plant water and monosubstituted ammonium phosphate. Microsilicon and finely ground mine burnt rock were used in compositions based on caustic magnesite. A comparative assessment of the air resistance of the developed compositions of modified gypsum and magnesite composites was carried out. It was found that the higher water resistance of the material, estimated by the value of the softening coefficient, does not necessarily guarantee its better resistance to alternate wetting and drying. It was revealed that the chemical composition and the nature of the crystallization structure of modified gypsum composites cause their better resistance to alternating stresses during cyclic wetting and drying in comparison with magnesite ones.