Activation of Hardening Processes of Fluorogypsum Compositions by Chemical Additives of Sodium Salts

Abstract

The article is devoted to modifications of fluorogypsum compositions by chemical additives of sodium salts in the form of sulfate, sulfite and sodium sulfide, as well as their combined effect on the kinetics of structure formation processes. Technological, ecological and technical aspects of utilization of fluorogypsum compositions activated by additives were investigated. Experiments have shown that an up to 3% increase in the amount of sodium sulfite additive leads to an increase in the compressive strength of samples at early stages of hardening (up to 14 days), whereas utilization of sodium sulfate additive forms a crystallization structure at later stages. Therefore, it is rational to combine sulfate and sodium sulfite additives in an amount not exceeding 3% of the binder’s weight. The binder hardening structure formation with sodium sulfide addition at early stages results in production of additional structure-forming substances such as calcium sulfide. The mechanism of differentiated application of individual sulfate and sodium sulfite additives allowed to suggest that combined sulfate and sulfite additives utilization seems to be the most rational decision, due to the fact that it is not a mere individual additives’ combination, but a buffer mixture, which means that the mechanism of such mixtures influence will be subject to the buffer action. The system will maintain a strictly defined pH range constancy, which determines stability of new growths, forming the hardening structure. However, using sodium sulfide as an additive and studying its impact on fluoroanhydrate compositions structure formation in both individual and combined with sodium sulfite and sodium sulfate forms appears to be as much reasonable. The combined Na2SO3-Na2SO4 additive activates hardening processes both at early and late stages. At the same time, columnar structures growing from the center to the periphery are formed, as indicated by electron-microscopic studies. Their growth stems from concentration gradient of SO42-- and SO32-- ions, which is in complete agreement with the other research data and is typical for both metal melts and cement systems solidification process.

Formation of porous structures in production technology of construction materials based on building gypsum plaster

“…The studies were performed at the maximum amount of carbon dioxide emitted. In papers [9][10][11][12][13][14][15], it was found that the specific surface of anhydrite binder of 300-400 m 2 /kg provides the increased hydration activity, and taking into account the presence of residual sulfuric acid on the surface of the acid fluoroanhydrite grains, the contact area and the rate of chemical reactions also increase. To activate the processes of neutralization and hydration of the binder, preliminary short-term grinding of fluoroanhydrite was carried out, followed by mixing with building gypsum plaster and additives.…”

Physical and mechanical properties of lightweight concrete based on gypsum binders and peat vermiculite granules

“…Влажность образцов после распалубки зависит от содержания гранул в композите, при соотношении торфовермикулитовые гранулы: гипс 20:80, влажность после распалубки равна 30%, при 80:20 -51%. Необходимо отметить, что при 30:70 достигаются оптимальные физические свойства по прочности, плотности и влажности при распалубке 6 [9,10].…”

“…Необходимо сказать, что увеличение или уменьшение рационального времени и интенсивности перемешивания приводит к ухудшению качества смеси, что в конечном итоге влияет на физико-механические свойства полученных легких бетонов. Так, например, при увеличении продолжительности перемешивания торфогипсовой смеси более 7 мин слабые частицы заполнителя разрушаются, в результате чего меняется гранулометрический состав исходных компонентов 8,9,10,11,12 [13,14]. При уменьшении времени перемешивания ухудшается качество материала за счет снижения гомогенности.…”

“…С. 353-358 10. Горкольцева Д. С. Исследование физико-механических свойств теплоизоляционных материалов на основе торфа // Перспективы развития фундаментальных наук: сборник научных трудов XVII Международной конференции студентов, аспирантов и молодых ученых.…”