Stroitel`nye Materialy №9

Table of contents

A.A. SEMYONOV, Candidate of Sciences (Engineering), General Manager ( «GS-Eхpert», ООО (18, office 207, the 1st Tverskoy-Yamskoy Lane, 125047, Moscow, Russian Federation)

Russian Market of Lime: Trends and Prospects

The state of the lime market in Russia is analyzed. Data on the commodity structure of production, investment projects being realized in the industry as well as ratings of lime manufac­ turers are presented. It is shown that the 10 largest producers of commercial lime manufacture about 70% of total production. The branch structure of lime consumption in Russia is also analyzed. On the basis of forecasts of development of the main consuming industries, the forecast of the lime market development for the period up to 2018 is presented.

Keywords: lime, commercial lime, technological lime.

V.I. ZUEV 1 , General Director (, A.E. MIKALUTSKY 1 , Chief of Technological Department; V.D. KOZHEVNIKOV 2 , Engineer-Technologist; I.V. BARSKY 3 , General Director
1 “Izvesta” Firm (231, 9 Yanvarya Street, 394019, Voronezh, Russian Federation)
2 OAO “Ashinsky Metallurgic Plant” (9, Mira Street, Asha, 456010, Chelyabinsk Region, Russian Federation)
3 OOO “Sibirsky Stroitel” (100, Yuzhny Microdistrict, Iskitim, 633208, Novosibirsk Oblast, Russian Federation)

Improvement of Shaft Counterflow Lime-Burning Kilns
On the basis of the analysis of exploited units operation as well as on the basis of results of many model tests, a new design of charging­distributing device for round and circular kilns operating under the pressure has been developed and patented. In comparison with all analogues used now it makes it possible to uniformly distribute the charge according to the size of a piece of charge in the kiln’s shaft regardless of its diameter. A new design of the company – peripheral tuyeres with the diameter reduced up to 90–125 mm and the weight reduced up to 50–70 kg – is described. For cooling casings it is provided to use the cooling liquid OZh­40 instead of technical water.

Keywords: shaft kilns, lime, charging­distributing device, tuyeres.

1. Patent RF 2525957. Zagruzochno-raspredelitel’noe us troistvo shakhtnoi pechi dlya obzhiga kuskovogo materiala [The loading distributing device of the mine kiln for roast ing of lumpy material] / Zuev V.I. Declared 20.09.2013. Published 20.08.2014. Bulletin No. 23. (In Russian).
2. Patent RF 144271. Shakhtnaya pech’ dlya obzhiga kus kovogo materiala [The mine kiln for roasting of a lumpy material] / Zuev V.I. Declared 31.03.2014. Published 20.08.2014. Bulletin No. 23. (In Russian).

B.A. FETISOV, Candidate of Sciences (Engineering) ( The Ural Federal University named after the first President of Russia B. N. Yeltsin (19, Mira Street, 620002, Yekaterinburg, Russian Federation)

Energy-Technological Efficiency of Fine Lime Production

The most rational schemes of the organization of process of carbonate raw burning and lime recycling in cyclone cascading kilns at various compositions and moisture levels of the par­ ent stock with due regard for cost­saving and quality of finished products and possibility of control over the thermal performance of the unit are analyzed by calculation with the help of a mathematical model. The choice of the most rational design was made using the method of directional improvement of the thermal­technological scheme that in the process of lime burning and recycling for each level of free moisture content made it possible to define the design and thermal behavior of the unit which are optimal according to the criterion of heat efficiency. Results of the mathematical simulation show that the optimal topology of the operating space of cyclone cascading furnaces is determined by the composition and moisture content of the carbonate raw. Cyclone cascading kilns are not inferior to shaft kilns for thermal efficiency and technical properties of the lime obtained and at that less demanding to the quality of raw materials used.

Keywords: lime, cyclone cascading kilns, carbonate raw burning, lime burners.

1. Monastyrev A.V., Galiakhmetov R.F. Pechi dlya proiz vodstva izvesti [Kilns for production of lime]. Voronezh: Istoki. 2010. 392 p.
2. Monastyrev A.V. State and prospects of use of cyclonic kilns for production of calcic and magnesian (dolomitic) lime. ALITINFORM. 2010. No. 6, pp. 33–46. (In Russian).
3. Fetisov B.A. Cascade kilns. B.I. Kitayev’s creative heri tage. Works of the International scientific and practical- conference. Ekaterinburg: UGTU–UPI. 2009, pp. 480– 485. (In Russian).

A.N. MAMAEV, Technical Director (, O.V. BOYKO, General Director OAO «Lipetskstalproekt» (1, Kalinina Street, 398059, Lipetsk, Russian Federation)

Modernization of Shaft Mixed Feed Kilns for Limestone Burning

Modernization of a shaft mixed feed kiln for limestone burning on the basis of modern methods of limestone burning and kiln designs is considered. Shaft mixed feed kilns for lime­ stone burning built in the XX century have a lot of shortcomings in the field of lining, gas tightness, dozing, gas purification, and automation. These shortcomings have been overcome by modifying the design of the kiln, the use of modern materials and automation. The kiln drawing is attached.

Keywords: limestone burning, shaft mixed feed kilns, lime producing.

A.B. LIPILIN, General Director, N.V. KORENYUGINA (, Chief Technologist «TECHPRIBOR» Plant (43, Pirogova Street, 301246 Shchyokino, Tula Oblast, Russian Federation)

Impact-Centrifugal Mills in Production of Building Lime
It is known that ground quicklime, as a binder, has a number of advantages in comparison with slaked lime. High dispersion of quicklime favours the improvement of technological pro­ cesses of building materials and products manufacturing, improvement of the quality of finished products. Favorable criterion of grinding fineness of quicklime is the absence of residue on the sieve № 02 and a small residue on the sieve № 008 (not more than 4–6%). A comparison of the technical­economical characteristics of the ball two­chamber mill 1456A and the impactive­centrifugal mill “TRIBOKINETIKA” is made; schemes of grinding plants with ball and impact­centrifugal mills are given.

Keywords: ground quicklime, impact­centrifugal mill, ball mill, impact grinding, lime grinding.

A.V. ARTAMONOV, Candidate of Sciences (Engineering) (, M.S. GARKAVI, Doctor of Sciences (Engineering), E.V. KOLODEZHNAYA, Candidate of Sciences (Engineering) ZAO “Ural-Omega” (89, Structure 7, Lenin Avenue, Magnitogorsk, 455037, Chelyabinsk Oblast, Russian Federation)

Properties of Lime of Centrifugal-Impact Grinding

The technology of production of technological (fluidized) lime for desulphuration of cast iron before converter melting has been developed. Putting a specially developed liquid hydro­ phobisator according to the method of molecular layering in the course of lime grinding ensures the production of a ready­made product with high fluidity and hydrophobicity.

Keywords: quicklime, centrifugal­impact mill, fluidized lime, hydrophobisator.

I.A. GALEEV, General Director ( OOO “INVEST-TECHNOLOGY” (20, Nakhimova Street, 454119, Chelyabinsk, Russian Federation)

Optimization of Production Process of Silicate Brick on the Example of the Factory in the City of Kaluga

OOO “INVEST­TECHNOLOGY” is specialized in the manufacture and supply of equipment for silicate brick factories. A new step in the company’s development is the turn­key construc­ tion of a production line at Kaluga building materials factory (productivity of 100 mil. conventional bricks per year). In the course of executing this project, the engineers of “INVEST TECHNOLOGY” Co. are based on the more than 20 year experience in designing silicate brick factories and other technological equipment. As a result, a technological line, main param­ eters of which exceed traditional technological schemes designed at present, has been developed. One of the most important advantages of the new technological line is its compact­ ness that makes it possible to realize the profound automation with the use of transmission bridges of relatively small overall dimensions; it reduces the price, simplifies the maintenance and reduces the operating costs.

Keywords: silicate brick, equipment, automation, mixer, press, technological line.

G.V. KUZNETSOVA (, Engineer, R.M. NUGMANOV, Student Kazan State University of Architecture and Engineering (1, Zelenaya Street, 420043, Kazan, Russian Federation)

Role of Technological Factors in Formation of Colour of Silicate Coloured Brick

The conversion of an operating line for production of silicate non­coloured brick for producing coloured brick has its own peculiarities; neglect of them leads to the off­grade brick out­ put. The originality of the technological process, workshop layout, the presence of draughts and cold season lead to the loss of color on the surface of the brick. The article contains the study of reasons for formation of white runs on the brick produced according to the technology of volumetric coloration of a slaked molding mix. The influence of climatic conditions in workshop premises on the temperature of the molding mix and adobe brick stage­by­stage and the temperature change during the time are shown. Results of the study and the role of temperature of colored adobe brick, lime, steam condensate in the autoclave at the first stage of steam curing of colored adobe brick are presented.

Keywords: mass­colored silicate brick, molding mix, adobe brick, silicate mix temperature.

1. Semenov A.A. The analysis of state of the russian silicate brick market. Stroitel’nye Materialy [Construction Materials]. 2010. No. 9, pp. 4–6. (In Russian).
2. Semenov A.A. State of the Russian market of silicate wall materials. Stroitel’nye Materialy [Construction Materials] 2013. No. 12, pp. 9–12. (In Russian).
3. Khavkin L.M. Tekhnologiya silikatnogo kirpicha [Tech nology silicate brick]. Moscow: EKOLIT. 2011. 384 p.
4. Babel A. Dosing and delivery of pigments for dyeing of silicate brick at “Borsky Silikatny Zavod” Stroitel’nye Materialy [Construction Materials]. 2013. No. 9, pp. 14–21. (In Russian).
5. Kuznetsova G.V., Khozin V.G. Influence of pigments on properties of slaked silicate moulding mix. Stroitel’nye Materialy [Construction Materials]. 2012. No. 9, pp. 25–28. (In Russian).
6. Rabinovich. V.A. Khavin V.Ya. Kratkii khimicheskii spravochnik. [Short chemical reference book]. Leningrad: Khimiya. 1991. 432 p.
7. Kuznetsova G.V., Sannikova V.I. Influence of hydro thermal treatment on quality of colored silicate brick. Stroitel’nye Materialy [Construction Materials]. 2010. No. 9, pp. 36–39. (In Russian).

E.I. YUMASHEVA, Engineer-Technologist ( Advertising and Publishing Company «Stroimaterialy» (9, Structure 3, Office 225, Dmitrivskoye Highway, 127434, Moscow, Russian Federation)

Unique Technical Solution for Realization of the Easternmost Investment Project of «KNAUF» Co.
On the example of OOO «KNAUF GIPS Baikal» the technical and marketing solutions for the efficient realization of the investment project and, after its completion, for the successful operation of a new enterprise for producing building materials on the basis of gypsum are shown. It is noted that the socially responsible policy of the investor has a beneficial effect on the development of the region where the enterprise is stationed.

Keywords: investment project, gypsum wallboards, dry building mixes, propane­butane mix, liquefied gas, compressed gas, information­consultation center.

1. Los L.M. «KNAUF» Group: 20 Years of investments in Russia – lessons and prospects. Stroitel’nye Materialy [Cons truction Materials]. 2013. No. 2, pp. 73–75. (in Russian).

G.R. BUTKEVICH, Candidate of Sciences (Engineering) ( Research and Design Institute for Extraction, Transportation and Processing of Mineral Raw Materials in Building Materials Industry (1, Volokolamsk Highway, Moscow, 125080, Russian Federation)

View of the Future of Non-Metallic Building Materials Industry
Technologies of mining operations and mineral raw materials processing in the course of producing non­metallic building materials are analyzed. Goals for improving technological pro­ cesses and reducing the loading on the environment are formulated.

Keywords: mineral raw materials, mining operations, non­metallic building materials.

1. Ucherov-Marsak A.V. Looking into the future con crete. Stroitel’nye Materialy [Construction Materials]. 2014. No. 3, pp. 4–5. (In Russian).
2. Kevin Yanik Aggregates sales forecast to rise nearly 6 per cent annually. Pit & Quarry. February, 2014, pр. 6–10.
3. Kutuzov B.N. Problems explosive destruction of rocks in mining. Gornyi zhurnal. 1997. No. 10, pp. 31–33. (In Russian).
4. Butkevich G.R. Problems of development of irrigated fields. Stroitel’nye Materialy [Construction Materials]. 2003. No. 7. pp. 12–13. (In Russian).
5. Kondrat’ev V.B. Mineral resources as a factor of eco nomic growth and global competitiveness. Gornaya pro myshlennost’. 2014. No. 1. pp. 6–10. (In Russian).

V.Yu. CHUKHLANOV, Doctor of Sciences (Engineering) (, O.G. SELIVANOV, Engineer, T.A. TRIFONOVA, Doctor of Sciences (Biology) Vladimir State University named after Alexander and Nikolay Stoletovs (87, Gorky Street, 600000 Vladimir, Russian Federation)

Polyvinyl-Acetate Binding Materials Modified with Alkoxysilane
Issues of improving operation characteristics, including moisture resistance, of polyvinyl­acetate binders due to their modification with organo­silicone compounds – alkoxysilanes, tet­ raethoxysilane among others ­ are considered. The mechanism of interaction of tetraethoxysilane with a polymer binder is considered; dependences of changing the properties of a polyvinyl­acetate binder on the concentration of tetraethoxysilane introduced into the composition are studied. It is shown that the introduction of 20–25% of tetraethoxysilane in the polyvinyl­acetate composition significantly improves the adhesion characteristics and moisture resistance of the binding material. Taking into account that tetraethoxysilane is toxic, research in determining the toxic index of developed polymer materials modified with an organo­silicone compound has been conducted. The research shows that developed materials with 20–25% of tetraethoxysilane in the polyvinyl­acetate binder have low toxicity.

Keywords: polyvinyl­acetate binder, tetraethoxysilane modifier, index of toxicity.

1. Tereshko A.E., Golikov I.V., Krasnobaeva V.S., Indei kin E.A. PVA paints, wax dispersions modified water. Izvestiya vysshikh uchebnykh zavedenii. Seriya: Khimiya i khimicheskaya tekhnologiya. 2006. Vol. 49. No. 3, pp. 67– 69. (In Russian).
2. Novikov V.T., Knyazev Al.S., Knyazev An.S. ets. Modification of PVA dispersion glyoxal to produce coat ings and adhesives. Lakokrasochnye materialy i ikh prim enenie. 2012. No. 10, pp. 32–33 (In Russian).
3. Chukhlanov V.Yu. and Ionova M. Water repellent poly mer coating based on oligopiperillenestryrene and alk oxysilane. American Journal of Polymer Science. 2013. Vol. 3. No. 1, pp. 1–5.
4. Kislova Yu. Russian market dispersions PVA. Lako krasochnye materialy i ikh primenenie. 2011. No. 1–2, pp. 8–9. (In Russian).
5. Chukhlanov V.Yu., Usacheva Yu.V., Selivanov O.G., Shirkin L.V. New coating materials based on modified binders piperilenstirolnyh using galvanic slimes as a filler. Lakokrasochnye materialy i ikh primenenie. 2012. No. 12, pp. 52–55. (In Russian).
6. Chukhlanov V.Yu., Ionova M.A. Alkoxysilane modified polyurethane coating with improved performance prop erties. Stroitel’nye Materialy [Construction Materials]. 2012. No. 4, pp. 60–61. (In Russian).
7. Peresin M., Vesterinen A., Habibi Y. and all. Crosslinked PVA nanofibers reinforced with cellulose nanocrystals: Water interactions and thermomechanical properties. Journal of Applied Polymer Science. 2014. No. 11, pp. 27–32.

V.S. GRYZLOV, Doctor of Sciences (Engineering), Cherepovets State University (5, Lunacharskogo Street, 162600, Cherepovets, Russian Federation)

Competency-Module Approach in the Course of Training of Bachelor-Builders
The methodology of the competency­module approach, when training bachelors in the field of construction, is presented. Functional and competency charts which are the basis of for­ mation of educational programs and training plans have been developed. A project of a credit­module educational program for Federal state educational standards for higher education (FGOS VO), direction 080301 is proposed. The main purpose of module education is the creation of educational structures flexible both in content and organization of training which guarantee the satisfaction of the requirement of a person and determine the vector of the new emerging interest. Thus, the pragmatic model of competences of the future specialist determines the scientific­knowledge model of educational process, demonstrates the participation of training modules in the transformation of tiered abilities and is a basis for develop­ ment of educational programs of bachelors training in the field of construction.

Keywords: competences, credit­module system, bachelor, construction.

1. Gryzlov V.S. Problems of Training of Masters of “Building” Profession. Zhilishchnoe Stroitel’stvo [Housing construction]. 2010. № 4, рр. 20–22. (In Russian).
2. Gryzlov V.S. Competence approach and the credit modular system of education. Visshee obrazovanie v Rossii. 2013. № 6, pp. 11–18. (In Russian).

S.V. FEDOSOV1, Doctor of Sciences (Engineering), Academician of RAACS, President (; V.G. KOTLOV2, Candidate of Sciences (Engineering), Counsellor of RAACS; R.M. ALOYAN 1, Doctor of Sciences (Engineering), Corresponding Member of RAACS, Rector; F.N. YASINSKI 3, Doctor of Sciences (Physics and Mathematics); M.V. BOCHKOV1 , Engineer
1 Ivanovo State Polytechnical University (20, Mart 8th Street, Ivanovo, 153037, Russian Federation)
2 Volga State University of Technology (3, Lenin Square, Yoshkar-Ola, Republic of Mari El, 424000, Russian Federation)
3 Ivanovo State Power Engineering University (34, Rabfakovskaya Street, Ivanovo, 153003, Russian Federation)

Simulation of Heat-Mass Transfer in the Gas–Solid System at Dowel Joints of Timber Structures Elements. Part. 3 Dynamics and kinetics of moisture transfer during moisture condensation and evaporation
Physical and mathematical models of heat transmission in dowel connection wood are presented. The physical model is based on the idea of wood to be a colloidal capillary­porous body. It was shown that under the changing parameters of the ambient temperature the dowel connection being maintained under (cooling to dew­point temperature) there occurs con­ densation of the condensed moisture by the Shchukarev’s law. The mathematical model is based on the non­stationary differential equation of hydraulic conductivity with boundary­val­ ue conditions where cyclical parameter and property changes of the interacting phases are taken into account. The results of the model calculations are provided.

Keywords: dowel connection, wood, mass transfer, condensation, micro­processes method.

1. Fedosov S.V., Kotlov V.G., Aloyan R.M., Jasinski F.N., Bochkov M.V. Simulation of heat-mass transfer in the gas- solid system at dowel joints of timber structures elements. Part. 1. General physical and mathematical problem. Stroitel’nye Materialy [Construction Materials]. 2014. No. 7, pp. 86–91. (In Russian).
2. Fedosov S.V., Kotlov V.G., Aloyan R.M., Jasinski F.N., Bochkov M.V. Simulation of heat-mass transfer in the gas- solid system at dowel joints of timber structures elements. Part 2. Dynamics of temperature fields at arbitrary law of changes of air environment temperature. Stroitel’nye Materialy [Construction Materials]. 2014. No. 8, pp. 73– 79. (In Russian).
3. Fedosov S.V. Teplomassoperenos v tekhnologicheskikh protsessakh stroitel’noi industrii [Heat and mass transfer in technological processes in construction industry]. Ivanovo: PresSto. 2010. 364 p.
4. Kasatkin A.G. Osnovnye protsessy i apparaty khimicheskoi tekhnologii [Basic processes and devices of chemical tech nology]. Moscow: State Research and Engineering Publishing House of chemical literature. 1961. 830 p.
5. Bogdanov E.S. Spravochnik po sushke drevesiny [Handbook of wood drying]. Edited by Bogdanov E.S. Moscow: Forest Industry. 1990. 304 p.
6. Lykov A.V. Teoriya sushki [Theory of drying]. Moscow: Energiya. 1968. 472 p.
7. Das B., Das A., Kothari V.K., Fangulero R., de Araujo M. Moisture transmission through textiles. Part 1: Processes involved in moisture transmission and the factors at play. AUTEX Research Journal. 2007. Vol. 7, No. 2, pp. 100–110.
8. Banerjee D., Zhao S., Schabel S. Heat transfer in thin po rous fibrous material: mathematical modelling and experi- mental validation using active thermography. AUTEX Research Journal. 2010. Vol. 10. No. 4, pp. 95–99.
9. Patent RF No. 1604945. Cl. E 04 B 1/49. Soedinitel’nyi ele ment dlya krepleniya derevyannykh detalei [Connec ting element for fastening wooden parts]. Kotlov V.G., Stepanov N.N. Published 08.07.1990. Bulletin No. 4612756. 3 p. (In Russian).
10. Patent RF No. 127775. Cl. E 04 B 1/49. Krepezhnyi element dlya soedineniya derevyannykh detalei [Fixing element for connecting wooden parts]. Kotlov V.G., Sharynin B.E., Muratova S.S. Published 10.05.2013. Bulletin No. 13. 3 p. (In Russian).
11. Comissarov Y.A., Gordeev L.S., Vent D.P. Protsessy i ap paraty khimicheskoi tekhnologii [The processes and appa ratuses of chemical technology]. Moscow: Khimiya. 2011. 1229 p.
12. Ugolev B.N. Drevesinovedenie i lesnoe tovarovedenie [Wood science and forestry merchandising]. 2nd ed. Moscow: Publishing Center Academy, 2006. 272 p.

V.I. KALASHNIKOV, Doctor of Sciences (Engineering), M.N. MOROZ, Candidate of Sciences (Engineering) (, O.V. TARAKANOV, Doctor of Sciences (Engineering), D.V. KALASHNIKOV, Candidate of Sciences (Engineering), O.V. SUZDALTSEV, Engineer Penza State University of Architecture and Civil Engineering (28, G. Titova Street, Penza, 440028, Russian Federation)

New Ideas about Action Mechanism of Superplasticizers Grinded Jointly with Cement or Mineral Rocks

Physical­chemical processes of the impact of superplasticizers (SP) on the dilution of cement­water and other mineral­water suspensions in the course of manufacturing of self­com­ pacting concretes of the new generation are considered. It is shown that the process of plasticization of the suspension from cement and mineral powder jointly milled with dry SP is the most efficient as significantly reduces the viscosity and yield point. It is established that pre­adsorption dry putting of SP on the mineral surface of micro­particles in the process of grinding and following mixing the suspension with water fundamentally changes the adsorption mechanism. It makes it possible to formulate a new idea in the adsorption mechanism: “adsorption of molecules of the adsorbent in the course of its dissolution on the adsorbate surface” unlike conventional classical idea: “adsorption of molecules of the adsorbent from the solution on the surface of the solid phase”.

Keywords: suspensions, superplasticizers, adsorption, dilution, concretes

1. Ibuk Kh. The drill bit of the ultra-high concrete. SPI. Mezhdunarodnoe betonnoe proizvodstvo. 2013. No. 3, рр. 28–30. (In Russian).
2. Zagmaister B., Doize T. Application over technological concrete on the basis of a special binder in the construction and engineering industries. CPI. Mezhdunarodnoe beton noe proizvodstvo. 2012. No. 1, рр. 26–32. (In Russian).
3. Liblang R., Ringvel’ski D. Effect of intensive mixing on the properties of ultra-strong concrete. SPI. Mezhdunarodnoe betonnoe proizvodstvo. 2012. No. 3, рр. 32–35. (In Russian).
4. Kalashnikov V.I. What is the powder-activated concrete of new generation. Stroitel’nye Materialy [Construction Materials]. 2012. No. 10, pp. 70–71. (In Russian).
5. Plank J und Sachgenhauser B. Experimental determina tion of the effective anionic charge density of polycarbox ylate superplasticizers in cement pore solution. Cement and Concrete Research. 39 (1). 2009. pp. 1–5.
6. Batrakov V.G. Modifitsirovannye betony [Modified con cretes]. Moscow: Stroiizdat. 1998. 768 p.
7. Babaev Sh.T., Komar A.A. Energosberegayushchaya tekhnologiya zhelezobetonnykh konstruktsii iz vysoko prochnogo betona s khimicheskimi dobavkami [Energy saving technology of reinforced concrete structures of high-strength concrete with chemical additives]. Мoscow: Stroiizdat. 1987. 240 p.
8. Batrakov V.G., Tyurina T.E., Falikman V.R. The plasti cizing effect of the superplasticizer at S-3 depending on the composition of cement. Concrete with effective modifying additives. NIIZhB. Moscow, 1985. pp. 8–14. (In Russian).
9. Kalashnikov V.I. Terminology of science of new genera tion of concrete. Stroitel’nye Materialy [Construction Materials]. 2011. No. 3, pp. 103–106. (In Russian).
10. Kalashnikov V.I. The calculated composition of high-strength self-compacting concrete. Stroitel’nye Materialy [Construction Materials]. 2008. No. 10, pp. 4–6. (In Russian).
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