Efficiency of gypsum binder modification with ultra-dispersed additives

The article presents the results of research on modifying gypsum rock with microadditives of inorganic salts, such as CaCl2 and CaSO4. The salts were added to the building gypsum as a 2 % solution at concentrations ranging from 0.2 to 1 %, with the dry salt consumption ranging from 0.004 to 0.02 % of the gypsum mass. All additives, when added in microdoses based on the gypsum mass, act as hardening accelerators and modifiers for building gypsum, increasing its strength. It has been proven that the strength gain of gypsum with microadditives of inorganic salts averages 2040 %. The optimal additive dosage is 0.20.4 % of the gypsum mass. The highest strength values were demonstrated by gypsum samples cured for 7 days with the addition of CaCl2 salt. The compressive strength of the gypsum binder was, on average, 1.351.40 times greater than that of gypsum without the added salt. Changes in the phase composition and microstructure of gypsum binders were observed with the addition of modifying additives. A compaction of the hydrated stone structure was observed due to the formation of highly dispersed hydrolysis products of inorganic salts. The studied ultrafine additives can be used to increase gypsum binder strength obtained by regenerating gypsum-containing waste from the aviation industry.