Heat-resistant concretes containing spent catalyst of petroleum refining

The possibility of utilizing disperse spent catalyst, a product of petroleum refining, is shown. The catalyst can serve as a finely divided admixture to heat-resistant concretes based on liquid glass binders. The mechanical and acoustic properties are studied for five compositions of the concrete with different content of the spent catalyst. The results obtained are compared with the properties of heat-resistant concrete with a finely divided chamotte admixture. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 1, pp. 19–22, January, 1997.     

Determination of the electrical conductivity of heat-resistant concretes

The problem of the electrical conductivity of heat-resistant concretes and bonding agents is considered and a method for determining this parameter is suggested. In addition to the thermal resistivity, the electric conductivity is a factor affecting the lifetime of lining materials for high-temperature devices. The problem is especially urgent in electric heaters. Translated from Ogneupory, No. 7, pp. 25–26, July, 1994.     

Use of technogenic formations in the production of unfired refractory composites

Use of inorganic technogenic raw material in composites with phosphate binders makes it possible to prepare a whole set of materials for special purposes: heat-resistant concretes and solutions, liquid phosphate binders, etc. From an ecological point of view these materials may be in demand in the same enterprises where they are formed, and this is a significant step on the path to waste-free technology.     

Heat-resistant thermally insulating concretes with phosphate and aluminate binders

This article describes heat-resistant thermally insulating concrete mixtures and products with phosphate and aluminate binders, their properties, and the main processes used to make them. The thermophysical properties required of thermal insulation are obtained together with an increase in its strength thanks to the production of denser but less heat-conducting concretes with fillers composed of aluminum microspheres.     

Effect of microsilicon on the properties of heat-resistant castable with chamotte scrap filler

Chamotte scrap with an elevated water absorption is used as a filler in low-cement heat-resistant concretes (castables) of the new generation. The studied castable compositions contain from S to 16% microsilicon. The effect of heat treatment of the castable to up to 1300°C on the change in its density, the ultimate compressive strength, deformation, and the speed of an ultrasonic pulse is determined. It is shown how microsilicon affects the setting of mortar and a hypothesis is made on the mechanism of the interaction of thin-phase components in the studied composition.     

New refractory concretes and binding systems: Basic trends of development, production, and use of refractories in the 21st century. Part III. Spinel and cast (self-flowing) concretes

The state-of-the-art in the field of creation and use of spinel, spinel-forming, and corundum-spinel concretes in the world is analyzed. In contrast to foreign-made concretes of this calss produced using high-alumina cement Russian specialists have developed cementless spinel concretes of the type of ceramic castables. Achievements in the field of low-cement self-flowing (cast) concretes, which are often more effective than vibrocompacted ones, are considered. The factors that determine their quality are analyzed. Concretes of this class can be obtained on the base of ceramic binders (HCBS). Due to their diminished (compared to low-cement concretes) water demand the materials can possess a lower porosity. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 4, pp. 12‐18, April, 1998. Parts I and II have been published in Nos. 2 and 3, 1998. To be continued.     

Experience with clay calcination in a vortex bed

Conclusions The experiments show that it is possible in principle to use new methods of calcining clays into grogs in equipment of the vortex type. In spite of the very short firing time, the clay substance undergoes extensive mullite formation, although the process of sintering cannot be considered as fully completed.The grog obtained can be used for making foamed lightweight fireclay refractories. This grog will find use for making heat-resistant concretes and mortars and also for refractory bricks.The experimental work on the calcination of refractory clays in a vortex furnace should be continued to explain the technical and economic effectiveness of firing and to produce coarse grogs and also data for planning an experimental-industrial plant.     

Petrographic investigation of the pore structure of alumina-silica refractory concretes

The results of a petrographic study of the pore structure of chamotte filler, the binder of alumina-silica refractory concretes, and stamped chamotte brick are presented. It is established that the pore structure of vibrationally cast alumina-silica concretes produced at the Semiluki Refractory Works consists mainly of round, closed pores. __________ Translated from Steklo i Keramika, No. 5, pp. 26–28, May, 2007.     

Corundum concretes based on modified phosphate-containing binders

Physicotechnical properties are provided for concretes based on mechanically-activated phosphate suspensions previously modified with magnesium and aluminum hydroxides and silicic acid. The results obtained demonstrate the efficiency of using modifying additions in order to increase the strength and heat resistance of corundum concretes. Translated from Novye Ogneupory, No. 5, pp. 32–35, May 2008.     

New forms of unmolded refractory materials produced by OOO Keralit

New forms of refractory materials are presented, produced by OOO Keralit: heat-insulating concretes, refractory concretes with low and normal cement contents, torcrete-mixes for heating furnace walls, and magnesia torcrete-mixes for hot repair of arc furnaces. Properties and fields of application for unmolded materials are provided. Translated from Novye Ogneupory, No. 7, pp. 21–23, July 2008.     

Preparation and properties of corundum HCBS and ceramic concretes. Part 3. Casting and volume constancy of ceramic concretes

Vibration casting and casting from a self-spreading mix with an original moisture content of molding systems of 3.8 – 4.2% are used to prepare coarse-grained (D _max = 10 mm) and medium-grained (D _max = 3 mm) corundum ceramic concretes with a corundum-mullite matrix system. Depending on the heat treatment temperature, the amount of their open porosity is 11 – 15%, and the ultimate strength in compression reaches 160 MPa. Both cast and compacted ceramic concretes have high volume constancy during heating or firing, and also in service. Linear shrinkage does not exceed 0.2 – 0.5%.     

A study of the applicability of waste catalyst in heat-resistant concrete

The authors describe the results of studying medium-cement heat-resistant concrete with an additive of waste catalyst (WC) that is generated at oil-processing plants and compare them with traditional microsilica and reactive alumina additives. Certain specifics of reactions between aluminate cement Gorkal-40 and the WC are identified, which accelerate the setting and hardening of concrete. The WC additive facilitates the formation of anorthite in the concrete matrix, which has a positive effect on the thermal resistance of heat-resistant concrete. __________ Translated from Novye Ogneupory, No. 8, pp. 58–62, August, 2006.     

Properties of aluminophosphate concretes containing various types of orthophosphoric acid

Conclusions The type of orthophosphoric acid has the maximum influence on the properties of corundum concretes, a lower influence on high-alumina concretes, and practically no influence on quartz-clay concretes. It is desirable to use wet-process orthophosphoric acid for refractory concretes. The excellent properties of concretes in the system A1₂O₃-SiO₂ based on this acid which is also cheaper enabled us to recommend it for preparing refractory concretes.The advantage of using H₃PO₄ of various types for corundum concretes is determined by the requirements placed on them in actual working conditions.Translated from Ogneupory, No.6, pp. 58–61, June, 1970.     

Properties of cast magnesial refractory concretes

Conclusions The rheological and physical properties of cast magnesial concretes and the relationship between these properties have been studied.It is established that with an increase in the compressive load, the shear deformation of the cast concretes decreases sharply and the concretes become more rigid. In the concretes studied, when rapid elastic deformation predominates, slow elastic deformation is observed to a lesser extent; and the plastic deformation of the cast concretes is quite insignificant. The viscosity of the experimental concretes is virtually the same and is independent of the composition of the concrete.The cast concretes are characterized by an adequate ultimate compressive strength, adequate thermal shock resistance after drying, a low deformation temperature under a load of 2 kgf/cm², and by very low gas permeability.Translated from Ogneupory, No. 6, pp. 36–41, June, 1979.     

Integrated shrinkage,relative humidity,strength development,and cracking potential of internally cured concrete exposed to different drying conditions

Internal curing (IC) technology using prewetted lightweight fine aggregates (LWFAs) as additives has been proved an effective means for mitigating both autogenous shrinkage and early-age cracking under sealed curing conditions. However, for practical structures in the field, concrete experiences more complex environmental conditions compared to under sealed curing. To better utilize internal curing technology for durable concretes, this study conducts comprehensive investigations on both control and internally cured concretes at water/cement (w/c) ratio of 0.3 and 0.4 in terms of the influence of age when concrete is exposed to drying and the drying duration on the developments of integrated shrinkage, internal relative humidity, compressive and flexural strengths, mass loss, and cracking potential. The results are beneficial for producing internally cured concrete with increased resistance to early-age cracking and enhanced durability for infrastructure applications.     

Scale resistance of some refractory concretes

Conclusions The scale resistance of refractory concretes when the latter interact with molten scale varies, and is primarily determined by the composition of the concretes. The highest scaleresistance is found in the dunite concretes and the lowest in the high-alumina; the chromemagnesite, chromite, and corundum concretes occupy the intermediate position.The scale in the solid state hardly interact with the concretes at all.The wear of the high-alumina and corundum concretes by molten scale occurs as the result of the formation of FeO·Al₂O₃ hercynite which forms a low-melting eutectic with the iron oxides (hercynite-wustite eutectic at 1330°C); hercynite is next replaced by magnetite and hematite which, after changing into FeO, form low-melting fayalite 2FeO·SiO₂ with SiO₂. The process of hercynite-formation and its replacement by iron oxides are accompanied by an increase in volume of roughly 16% and this leads to the swelling and deformation of the concretes.The wear of the chrome-magnetite and chromite concretes is accompanied by the appearance of new formation of the magnomagnetite and high-iron chrome-spinel type.Translated from Ogneupory, No. 1, pp. 43–47, January, 1979.     

Strength of corundum concretes

Conclusions Studies were made of the strength properties of corundum concretes containing a hydraulic bond, and an assessment was made of bending strength in relation to the heat-treatment temperature.It is shown that the concretes investigated belong to nonlinearly deformable materials. We determined the true strength of the concretes, which with rise in temperature increases; the strongest are concretes with a bond from hydraulically setting cement — Talum cement.We determined the maximum bending deformation of the concretes. It is shown that the lower the elastic deformation shown by the refractory material before failure then the less catastrophically will the destruction occur.We determined the densities of the full energy of deformation and the elastic energy at temperatures of 120, 1400, and 1750°C. It was established that concretes characterized by maximum strength possess the greatest stock of densities of full and elastic energy.On the basis of the deformation diagrams obtained for nonlinear-elastic concretes we determined the magnitudes of static and dynamic elasticity moduli. The strongest concretes are characterized by the maximum modulus values.Translated from Ogneupory, No. 6, pp. 9–14, June, 1986.     

Strain model for traditional and self‐compacting concrete during fire

In this paper, a complete strain model is derived that describes the strains developed during fire (up to 400 °C) and is based on the model of Anderberg et al., published in 1976. This model describes the total measured deformation as a superposition of four strain types: free thermal strain, instantaneous stress‐related strain, creep strain and transient strain. The strains are derived from loading tests on cylinders with dimensions Ø106 × 320 mm, submitted to load ratios of 0%, 20% and 30% of the initial strength before heating. For damage to the oven to be avoided, the instantaneous stress‐related strain is found from Young's modulus tests immediately after cooling. All tests occurred at a heating rate of 5 °C/min, and the specimens were pre‐dried to avoid explosive spalling. The investigated concretes are a traditional and a self‐compacting concrete with a testing age of about 30 months. Only small differences between both concrete types are found for the transient strain despite the different fracture of cement matrix. For the studied test conditions, the modern siliceous concretes such as self‐compacting concrete yielded similar results as the traditional siliceous concretes tested in the 1970s. Copyright © 2012 John Wiley & Sons, Ltd.     

Effect of binder content on the performance of alkali-activated slag concretes

This paper assesses the mechanical and durability performance of concretes produced using alkali silicate-activated ground granulated blast furnace slag as sole binder. Alkali-activated concretes are formulated with 300, 400 and 500 kg slag per m³ of fresh concrete, and their performance is compared with reference concretes produced using Portland cement (OPCC). Regardless of the binder content, the alkali-activated slag concretes (AASC) develop higher compressive strength than the comparable reference concretes. A higher binder content leads to increased strength in both AASC and OPCC at 28 days. However, at 90 days, the performance penalty for low binder content is more significant in the OPCC than AASC samples. Permeability, water sorption and carbonation resistance properties are also improved at higher binder contents. By controlling mix design parameters, it is possible to produce AASC with mechanical strength and durability comparable to conventional Portland cement concretes.     

High-alumina concretes and objects based upon them used for metal pouring

High-alumina concretes have been developed in OOO MetOgneupor for the production of objects for siphon steel pouring. Information is provided about the objects developed and their operating experience under ZAO MRK (mechanical repair unit) OAO MMK conditions. Translated from Novye Ogneupory, No. 3, pp. 11 – 12, March 2009.