Refractory concrete based on high-alumina cement and clinker aggregate

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The Effect of Fine-Ground Glass on the Hydration Process and Properties of Alumina-Cement-Based Composites

This paper discusses studies regarding the impact of fine-ground glass additives on the hydration and properties of alumina cement pastes and mortars. Fine-ground glass was added to pastes and mortars instead of high-alumina cement and calcium aluminate cement in quantities of 5% and 10%. The findings are inconclusive as to the impact of glass on the properties of tested alumina cement types. The effect produced via the addition of glass instead of cement depends on the type of alumina cement used. Adding fine-ground glass to high-alumina cement enhances the paste’s density while improving paste and mortar strength. Using the same additive for calcium aluminate cement reduces its density and strength. The addition of glass to high-alumina cement adversely affects its strength at higher temperatures.

STUDY OF THE EFFECT OF PARTICULATE ADDITIVES ON THE SETTING TIME AND MICROSTRUCTURE OF HIGH-ALUMINA CEMENT

the paper is devoted to a full-scale study of corundum modifying dispersed additives (reactive, tabular, dispersing alumina) and artificial ceramic binder, their impact on high-alumina cement microstructure and setting time. Artificial ceramic binders are characterized by similar chemical, phase and grain composition with modifying corundum additives and characterized by the presence of particles less than 100 nm (up to 0.5%). The studied materials are finely dispersed polyfractional systems from 0.1 to 13 μm with a prevailing grading fraction of 2-10 μm. In this case, dispersing and reactive alumina are more coarse. Using the microscopy method it was established that the corundum additives increase packing density of high-alumina cement samples, especially with artificial ceramic binder addition. Studies of dispersed additives effect on the setting time of cement was conducted. It is established that the adding of artificial ceramic binder or dispersing alumina at 0.5% is speeding up the initial setting, but a further increasing of the additive content does not affect this indicator. The maximum reduction of setting time is caused by the introduction of 5% tabular alumina.

Effect investigation of the dispersion and type of fine-ground component, as well as the type of dispersing additives on the properties of low-cement periclase castable and samples from it

Researches have been carried out, as well as technological parameters have been developed for obtaining of low-cement periclase castable and products from it based on sintered periclase, periclase scrap, high alumina cement and dispersing additives. The possibility of using as cement brand of “VGTS-73” of own production of JSC “URIR named after A. S. Berezhnoy”, as well as cement Gorkal-70 (Poland) is established. The dispersion of fine-ground component of charge (mainly periclase and in a small amount of high alumina cement) and the possibility of using Castament FS-10 + Castament FW-10 (Germany), SioxX-Mag (Norway) and Lithopix P 5 (Germany) are established. Castament FS-10 + FW-10 and SioxX-Mag are more effective in terms of obtaining periclase castable products with better service properties. The temperature of thermal treatment of unburned products (350 оC), the firing temperature of products (~ 1450 оC) and the possible application temperature of fired products (1580 оC and above) are established. The developed low-cement periclase castables and samples from them are characterized, depending on the used dispersing additives, by the following indicators of physicochemical properties: content, wt. %: MgO — 85—86, SiO2 — 2.0—6.0, CaO — 1.5—2.5, Fe2O3 — not more than 2.0; grain composition, mm — 6—0; open porosity of the samples after thermal treatment at temperatures of 350 and 1450 оC is 20.3—23.0 and 18.8—22.8 %, respectively; apparent density of the samples after thermal treatment at temperatures of 350 and 1450 оC is 2.63—2.69 and 2.74—2.86 g/cm3, respectively; cold crushing strength of the samples after thermal treatment at 350, 1450 and 1580 оC — 19—38, 31—65 and 29—72 N/mm2, respectively; refractoriness under a load of 0.2 N/mm2 of the samples after thermal treatment at 1450 оC is 1450—1470 оC. The developed low-cement periclase castables and products from them are recommended for service in the conditions, above all, the impact of basis slags. The manufacture of castables and products from them is mastered at the pilot production of JSC “URIR named after A. S. Berezhnoy”.

Effects of Nano-SiO2 on Properties of Spinel-Containing High Alumina Cement

This research was studied the effect of 15 nm SiO2 on the hydration behavior, hydration process and microstructure of spinel-containing high alumina cement (HAC), which is from high titanium blast furnace slag via smelting reduction method of Ti-Si-Fe making process. The results showed that with the increase of nano-SiO2, the heat released rate of hydration and the maximum peak were decreased and advanced. Accumulation of hydration heat to release was considerably improved before 16h. Nano-SiO2 can promote the formation of hydration products or promote the hexagonal phases CaAl2O4·10H2O and Ca2Al2O5·8H2O change into cubic phase Ca3Al2O6·6H2O, which has the pozzolanic and filler effects, which The pore size distribution of the hydration products was enhanced by nano-SiO2. At the same time, the flexural and compressive strength was increased gradually.