Матеріалознавство
Постійний URI для цього зібранняhttps://repositary.knuba.edu.ua/handle/987654321/1859
Переглянути
Документ 35. The influence of complex additive on strength and proper deformations of alkali-activated slag cements(Trans Tech Publications Ltd, 2019) Krivenko, Pavel; Petropavlovskyi, Oleh; Rudenko, Igor; Konstantynovskyi, OleksandrThe peculiarity of alkali-activated slag cements (further, AASC’s) is increased proper deformations, which can cause increased cracking and reduced durability of structure. The paper is devoted to manage AASC’s proper deformations. The main task was to determine the composition of complex additives (further, CA’s) in system «ordinary portland cement (further, OPC) clinker -mineral compound of different anionic type - surfactant» in presence of sodium metasilicate (further, MS) to affect on hydrated AASC performance while ensuring effective structure of artificial stone by criterion of shrinkage deformations. Comparative analysis of hydrated cement systems "OPC clinker - MS", "OPC clinker - mineral compound - MS" and "OPC clinker - mineral compound - MS - surfactant" showed that the greatest effect on reduction of proper deformations occurs when the mineral compounds relate to electrolytes, i.e. Na2SO4 and NaNO3. Hydrated system is characterized by expansion (+0,062 mm/m) in presence of Na2SO4. Almost no shrinkage is supplied by application of NaNO3 (-0,062 mm/m). The obtained CA’s were tested in AASC. CA in the system “OPC clinker - NaNO3 - surfactant” provides the initial setting 43 min, the end - 65 min with accelerated strength. Investigated AASC can be classified as non-shrinking cement. This phenomena is ensured by increasing density, homogeneity and monolithicity of hydrosilicate formations, as well as due to formation of hydroaluminosilicate structures with different morphology by inclusion of nitrate anions.Документ Alkali activated portland cement with adjustable proper deformations for anchoring application(IOP Publishing Ltd, 2019) Krivenko, P. V.; Rudenko, I. I.; Petropavlovskyi, O. M.; Konstantynovskyi, O. P.; Kovalchuk, A. V.The application of alkali-activated Portland cement (hereinafter AAPC) for anchoring grouts was investigated with obtaining of non-shrinking high performance cementing systems. The AAPC system “ordinary Portland cement clinker – sodium metasilicate” was modified by the complexes of mineral and organic compounds to ensure specified properties of anchoring grouts. It was revealed that the most effective multifunctional additives are represented by the system “salt-electrolyte – surfactant”. Alongside with slowing down of AAPC paste setting time, the effect of compensated shrinkage of AAPC mortar, i.e. expansion within 0.062 mm/m and slight shrinkage within 0.017 mm/m, was ensured when Na2SO4 and NaNO3 were used in the mentioned system respectively. The effect of compensated shrinkage is explained by greater crystallization of ydrosilicates and hydroaluminates, additional formation of sulfate-containing sodium-calcium hydroaluminate (for Na2SO4-based system) and crystalline calcium hydronitroaluminate (for NaNO3-based system). The advantages of the modified AAPC for anchoring application are indicated in thepaper.Документ Alkaline aluminosilicate binder-based adhesives with increased fire resistance for structural timber elements(2019) Krivenko, P. V.; Guzii, S. G.; Bondarenko, O. P.The paper presents data on the use of the alkaline aluminosilicate binder-based adhesive of the system Na2O•Al2O3•(4-6)SiO2•(17-20)H2O for gluing and fire protection of structural timber elements. The results of the study of thermoresistant phases in the reaction products of the alkaline aluminosilicates are reported and discussed. The results allowed to show that at SiO2/Al2O3 between 5 and 6 the zeolite-like phases of heulandite types, which, under action of temperatures, are able to form a porous aluminosilicate artificial stone with low thermal conductivity (λ=0.09 Wt/m⋅К, DSTU B V.2.7-105-2000 (GOST 7076-99)) are formed in the reaction products. The use of the developed aluminosilicate adhesives allow for to classify the structural timber elements as hardly burnable and hardly flammable materials (GOST 12.1.044-1989, EN 13823 + A1: 2014-12, ASTM E119-07). They have the following characteristics: water resistance D3 (EN 204:2001), resistance in splitting up 7.8 MPa (GOST 16483.5-1973), adhesion in normal pull-off test up to 2.6 MPa (GOST 32299- 2013 (ISO 4624:2002)).Документ Autoclaved aerated concrete in Ukraine(2020) Lapovska, Svitlana; Demchenko, Tetyana; Dyuzhilova, NataliyaThe article provides an overview of Ukrainian enterprises that produce autoclaved aerated concrete. The range of products manufactured for the period 2016-2019 is considered. The performance of enterprises and systemic technical solutions for the installation of energy-efficient exterior walls from AEROС LLC are analyzed.Документ Complex multifunctional additive for anchoring grout based on alkali-activated portland cement(IOP Publishing, 2020) Krivenko, P. V.; Petropavlovskyi, O. M.; Rudenko, I. I.; Konstantynovskyi, O. P.; Kovalchuk, A. V.Complex multifunctional additive (further, CA) which consists of aluminum powder, surfactant, salt-electrolyte (NaNO3) and calcium sulfate hemihydrate (CaSO4∙0.5H2O) is proposed for ensuring necessary properties of anchoring grouts based on alkali-activated portland cement (further, AAPC) presented by the system «ordinary portland cement clinker - sodium metasilicate». Specified consistency of fresh AAPC mortar along with it strength after hardening are provided by water reducing due to application of modified polyethylene glycol characterized by stability of molecular structure in AAPC hydration medium. CA influence on shrinkage mitigation in AAPC mortar is explained both water-reducing effect and gas release with volume increasing during formation of dispersive-coagulation structure. Expansion of crystallization-condensation structure is ensured due to stress of calcium hydrosulfoaluminate 3CaO∙Al2O3∙3СаSО4∙32H2O and calcium hydronitroaluminate ЗСаО∙А12О3∙Са(NO3)2∙10Н2О which form due to presence of СаSО4∙0,5H2O and NaNO3 in CA. Time matching of gas release with structure formation insures dense microstructure due to filling of pores by hydrated phases that causes lower excess stress during crystallization. CA ensures necessary performances of AAPC anchoring grout: consistency 190 mm; workability retention time 15 min; tensile strength in bending / compressive strength 6.1 / 25.7 MPа and 12.9 / 68.5 MPa in 1 d and 28 d agreeably; adhesion 0.9 MPa; linear extension up to +0.37 mm/m.Документ Design of fire-resistant heat- and soundproofing wood wool panels(2019) Tsapko, Yu.; Zavialov, D.; Bondarenko, O.; Pinchevsʹka, O.; Marchenko, N.; Guzii, S.Проведеними дослідженнями встановлено можливості виготовлення тепло- та звукоізоляційних матеріалів для облаштування приміщень. Сировиною для їхнього виробництва є деревні волокна, які виготовляють у виді плоских плит. Встановлено механізми процесу тепло- та звукоізоляції при передаванні енергії через матеріал, що дає можливість впливати на цей процес. Доведено, що вони полягають у зниженні пористості матеріалу. Так, зі зменшенням об’ємної маси матеріалу, теплопровідність і передача звуку зменшується, і навпаки. Крім того, тепло- та звукоізоляційні будівельні матеріали з деревини повинні задовольняти наступним вимогам: мати стабільні теплоізоляційні і акустичні показники протягом усього періоду експлуатації та бути вогнестійкими і не виділяти в навколишнє середовище шкідливих речовин. Експериментальними дослідженнями підтверджено, що матеріал на основі деревної шерсті і неорганічного в’яжучого при співвідношенні 1:1 відноситься до горючих матеріалів, оскільки, під час температурного впливу було зафіксовано його тління. Так, під термічною дією протягом 90 с матеріал зайнявся і полум’я поширилося по першим трьом зонам протягом 41 с. Натомість, підвищення кількості в’яжучого на неорганічній основі та застосування органо-мінерального в’яжучого, не призводить до загорання матеріалу. При цьому максимальна температура димових газів становила близько 120 °C, а індекс горючості складав 0 за рахунок розкладання антипіренів під дією температури з виділенням негорючих газів, які гальмують процеси окиснення матеріалу та суттєво підвищують утворення на поверхні матеріалу теплозахисного шару коксу. Це приводить до гальмування теплопередачі високотемпературного полум’я до матеріалу. Завдяки цьому стало можливим визначення умов вогнестійкості матеріалу шляхом утворення бар’єру для теплопровідності. Це дозволяє стверджувати про відповідність виявленого механізму формування властивостей матеріалу на основі деревної шерсті і неорганічного та органо- мінерального в’яжучого та практичну привабливість запропонованих технологічних рішень. Останні, зокрема, стосуються визначення кількості складової в’яжучого, оскільки при малих кількостях проходить процес горіння. Таким чином, є підстави стверджувати про можливість спрямованого регулювання процесів формування деревинних тепло- та звукоізоляційних матеріалів шляхом використання деревної шерсті і неорганічного та органо-мінерального в’яжучого, які здатні утворювати на поверхні матеріалу вогнезахисну плівку.Документ Development of decisions for alkali-activated cements proper deformations control(ПП «Технологічний Центр», 2019-11) Krivenko, P.; Gots, V.; Petropavlovskyi, O.; Rudenko, I.; Konstantynovskyi, O.; Kovalchuk, A.The relevance of using cements containing mineral admixtures of both natural and artificial origin is determined by compliance with current trends in sustainable mankind development in terms of efficient consumption of raw materials and energy and responsible attitude to the environment. From the environmental point of view, partial replacement of cement clinker with mineral admixtures contributes to the reduction of CO2 emissions. In addition, materials based on such cements are characterized by high quality, functionality and durability. For example, efficiency of using blast furnace slag, zeolite and limestone in composite eco-cements with high initial strength has been demonstrated [1].Документ Development of solutions concerning regulation of proper deformations in alkali-activated cements(ПП «Технологічний Центр», 2019-11) Krivenko, P.; Gots, V.; Petropavlovskyi, O.; Rudenko, I.; Konstantynovskyi, O.; Kovalchuk, A.The essence of the problem related to proper deformations in alkali-activated cements (AAC) complicated with high content of gel-like hydrate formations was analyzed. Cement types diametrically opposite in their compositions and, accordingly, in the content of gel phases during hydration, that is, the alkali-acti�- vated portland cement (AAPC) and alkali-activated slag cement (AASC) were taken for consideration. Approaches to formation of an effective structure of artificial stone counteracting shrinkage deformation by means of interference in structure formation when using complexes of mineral and organic compounds were proposed. Such compounds in composition of complex organomineral admixtures jointly influence intensification of crystallization processes and formation of an effective pore structure and morphology of hydrate phases while reducing water content in artificial stone. Salt electrolytes of various anionic types and anion-active surface-active substances were considered as ingredients of the proposed complex modifying admixtures. It has been found that the “salt electrolyte–surfactant” system is the most effective for AAPC modification. It was shown that modification of AAPC with this complex admixture based on NaNO3 reduced shrinkage from 0.406 to 0.017 mm/m. Instead, the use of Na2SO4 provided AAC of this type with a capacity of expansion up to 0.062 mm/m. It was shown that the effect of compensated shrinkage of modified AAPC is associated with a higher crystallization of low-basicity hydrosilicates (CSH(B)) and calcium hydroaluminates (CaO∙Al2O3∙10H2O). An additional effect is associated with formation of sulfate-containing sodium-calcium hydroaluminate (for the Na2SO4-based system) and crystalline calcium hydronitroaluminate (for the NaNO3-based system) with a corresponding microstructure stress. For further development, a complex admixture of “Portland cement clinker–salt electrolyte–surfactant” system was proposed for AASC modification. It provided shrinkage reduction from 0.984 mm/m to 0.683 mm/m. Minimization of the modified AASC shrinkage was explained by formation of sodium hydroalumosilicate of gmelinite type ((Na2Ca)∙Al2∙Si4∙O12∙6H2O) with a high degree of crystallization along with low-basicity calcium hydrosilicates. It was noted that the cement stone structure is characterized by high density, uniformity, and consolidation of hydrate formations.Документ Effect of a flame-retardant coating on the burning parameters of wood samples(2019) Tsapko, Yu.; Bondarenko, O.; Tsapko, A.Wood is widely used as a building material in construction and architecture due to its mechanical and operational properties. However, because of its high combustibility, it is a fire-hazardous material. Level of fire safety of objects in which wood building structures are used can be raised by means of fire protection treatment, namely, providing the wood with the ability to withstand flame and its surface propagation, preventing free access of oxygen which promotes wood destruction and accelerates the burning process.Документ Efficiency of Redispersible Polymer Powders in Mortars for Anchoring Application Based on Alkali Activated Portland Cements(Trans Tech Publications, 2018) Rudenko, Igor I.; Konstantynovskyi, Oleksandr P.; Kovalchuk, Artem V.; Nikolainko, Marharyta V.; Obremsky, Dmytro V.Properties of dry mixes for anchoring application (increasing of mortars strength, adhesion, volume stability etc.) based on alkali activated Portland cement (AAPC) are influenced by different factors. One of them is application of chemical admixtures with different functionality. Adhesive properties are mainly achieved by redispersible polymer powders (RPP). The main problem in choice of RPP’s type is destruction of their molecules with ester links due to alkaline hydrolysis. The purpose of work was investigation of RPP’s molecular structure influence on properties of mortar for anchoring application based on AAPC and determination of the most effective. Efficiency of RPP based on copolymer of versatile acid ester was shown. The application of this RPP provides adhesion of 1.1 MPa and consistency of 190 mm. Positive effect of copolymer of ethylene and vinyl acetate was shown despite of partial destruction of RPP’s molecule as a result of alkaline hydrolysis of vinyl acetate at early terms of hardening. Negative effect of RPP is in decreasing of mortar strength. Thus this problem solving is decreasing of powder content to values which provide necessary physical-mechanical properties (strength, adhesion).Документ Enhancement of alkali-activated slag cement concretes crack resistance for mitigation of steel reinforcement corrosion(EDP Sciences, 2020-04-22) Petropavlovskyi, Oleh; Kovalchuk, Oleksandr; Krivenko, Pavlo; Rudenko, Igor; Konstantynovskyi, OleksandrThe paper is devoted to mitigation of steel reinforcement corrosion in alkali-activated slag cement (further, AASC) concretes, based on soluble sodium silicates (further, SSS's), obtained from high consistensy concrete mixes. Enhancement of AASC fine concretes crack resistance due to modification by complex shrinkage-reducing additives (further, SRA's) based on surfactants and trisodium phosphate Na3PO .12H2O (further, TSP) was proposed for mitigation of steel reinforcement corrosion. SSS's were presented by sodium metasilicate (silica modulus 1.0, dry state) and water glass (silica modulus 2.9, density 1400 kg/m3). In case of sodium metasilicate the application of SRA composition "ordinary portland cement clinker - TSP - sodium lignosulphonate - sodium gluconate" provides enhancement of crack resistance starting from early age structure formation with restriction of drying shrinkage from 0,984 to 0,713 mm/m after 80 d. The effect is caused by reduction of water and by higher volume of crystalline hydrates. In turn, SRA presented by compositions "TSP - glycerol" and "TSP - glycerol - polyacrylamide" provide enhancement of AASC fine concretes fracture toughness during late structure formation with increasing ratio of tensile strength in bending to compressive strength up to 37 - 49 % if compare with the reference AASC when water glass is used.Документ Enhancement of alkali-activated slag cement concretes crack resistance for mitigation of steel reinforcement corrosion(EDP Sciences, 2020-04) Krivenko, Pavlo; Petropavlovskyi, Oleh; Kovalchuk, Oleksandr; Rudenko, Igor; Konstantynovskyi, OleksandrThe paper is devoted to mitigation of steel reinforcement corrosion in alkali-activated slag cement (further, AASC) concretes, based on soluble sodium silicates (further, SSS’s), obtained from high consistensy concrete mixes. Enhancement of AASC fine concretes crack resistance due to modification by complex shrinkage-reducing additives (further, SRA’s) based on surfactants and trisodium phosphate Na3PO4.12H2O (further, TSP) was proposed for mitigation of steel reinforcement corrosion. SSS’s were presented by sodium metasilicate (silica modulus 1.0, dry state) and water glass (silica modulus 2.9, density 1400 kg/m3). In case of sodium metasilicate the application of SRA composition “ordinary portland cement clinker – TSP – sodium lignosulphonate – sodium gluconate” provides enhancement of crack resistance starting from early age structure formation with restriction of drying shrinkage from 0,984 to 0,713 mm/m after 80 d. The effect is caused by reduction of water and by higher volume of crystalline hydrates. In turn, SRA presented by compositions “TSP – glycerol” and “TSP – glycerol – polyacrylamide” provide enhancement of AASC fine concretes fracture toughness during late structure formation with increasing ratio of tensile strength in bending to compressive strength up to 37 – 49 % if compare with the reference AASC when water glass is used.Документ Establishment of heat-exchange process regularities at inflammation of reed samples(2019) Tsapko, Yu.; Bondarenko, O.; Tsapko, A.At present, reed is growing in popularity as an environmentally safe roofing material. However, it is classified as a flammable material. To reduce this shortcoming, flame-retarding treatment is used, which makes this material resistant to inflammation.Документ Features of studying the efficiency of fire protection of a wooden wall with external exposure to the flame of combustible substances(2019) Tsapko, Yu.; Bondarenko, O.; Pinchevska, О.; Buys’kykh, N.; Lakida, Yu.The article analyzes the physical ways to provide the necessary limit of fire resistance of wooden structures, which have significant disadvantages, namely, leading to significant material costs and increase the volume of structures. Modern methods of fire protection of building structures are based on the use of blocking coatings, which are complex systems of organic and inorganic components. Studies of the combustibility of wood have shown that a raw specimen of timber construction is capable of engaging and spreading flames on the surface. Instead, the structure treated with the organo-mineral protective coating did not burn after combustion of the model hearth, respectively, and did not break down. The swelling of the protective coating was recorded, and the temperature on the reverse floor was less than 140ºC. As a result, it was ascertained that the effectiveness of the shredded image of the tree’s construction was 4.4 times higher for the protected organic and mineral coatings 3.3 times higher - for the clear protection of non-organic ones. It’s necessary to assimilate a coke ball on the surface of the construction, which will add to the temperature and the temperature glyphine, with which the hour of reaching the boundary temperature will be improved.Документ Fillers for modification of polyester powder coating(IOP Publishing Ltd, 2020-09) Gots, V. I.; Lastivka, O. V.; Tomin, O. O.; Tymoshenko, S. A.In the article effectiveness of the use of fillers to improve the physical and mechanical properties of the coating varied depending on the average size of the filler particles and crystalline shape was studied. According to the indicators of impact strength to back impact and bending strength of the coating, the most effective is the use of microsilica with an average size of 2.9 μm. As the average filler size increases, the gloss and impact strength of the coating reduce. To increase the bending strength of the coating, it is advisable to use fillers in the form of wollastonite, which is characterized by a fibrous crystal shape, which improves the physical and mechanical properties of the coating and prevents cracking, acting as a reinforcing agent. In addition, the analysis of the obtained study results shows that the use of the studied Ukrainianmade fillers in the powder paint composition promotes obtaining a covering with adjustable physical and mechanical characteristics.Документ Increase of fire resistance of coating wood with adding mineral fillers(Transbud-2018, 2018) Tsapko, Y.; Kyrycyok, V.; Tsapko, A.; Bondarenko, O.; Guzii, S.The article covers all the stages of the process of fire protection: as the separation of gases, heat transfer, the swelling of the coating, which is formed during by the action of fire. To determine the fire protection efficiency in the coatings developed, studies have been carried out on determining the combustibility of wood in terms of mass loss and increase in the temperature of flue gases, and it has been established that mass loss of coated wood does not exceed 3% and the temperature does not exceed 160°C. The results of the determination of the protection efficiency for the system have shown that under the influence of the hightemperature flame of burning of the material and the loss of the mass of the coating is reduced due to the formation of high-temperature compounds, while the time to reach the limiting temperature increases. Studies on determining the quality of fire protection wood treatment by coating showed that the rate of cooking for a rough sample of wood was more than 2 mm/min, for fire-proof samples - did not exceed 0.5 mm/min, which makes it possible to conclude that it is advisable to use them.Документ Influence of whitening additives on the properties of decorative slag-alkaline cements(IOP Publishing Ltd, 2020-09) Gots, V. I.; Gelevera, O. G.; Petropavlovsky, O. N.; Rogozina, N. V.; Smeshko, V. V.Traditional decorative cements are made on the basis of white cements and the demand for them is constantly growing. But such cements have all the disadvantages of clinker cements, namely, high energy intensity and high price. An alternative may be slag-alkali cements having higher physical and mechanical characteristics and lower price. Therefore, these studies were aimed at choosing such additives that would have the maximum whitening properties and would enhance the stabilization of bleaching processes during hydration and hardening of slag in the presence of alkalis, to determine the simultaneous effect of three additives on the whiteness and physical-mechanical characteristics, as well as to determine the optimal the content of these additives in slag-alkali decorative compositions. In this work, as a result of the studies performed, the possibility of obtaining effective slag-alkali white cements as the basis for the production of decorative concrete with acceptable economic characteristics is proved. The influence of each of the bleaches on such characteristics of decorative slagalkali cements as strength, setting time, whiteness is established. Methods for optimizing compositions are identified.Документ Modification of the structure of the stabilized basalt fiber(IOP Publishing Ltd, 2020-09) Gots, V. I.; Palchyk, P. P.; Tymoshenko, S. A.; Palchyk, S. P.The study of thermophysical, physical-mechanical and acoustic characteristics of coarse continuous basalt fiber in the conditions of influence of operational factors and corrosion environment is carried out. It is shown that obtaining barrier materials with high thermophysical and acoustic properties is possible by creating a porous system in the material with a predetermined textural characteristic of pores of different class, purpose and combination. The influence of the porous system of coarse continuous basalt fiber on the operational properties of flexible heat and sound insulation products and materials has been studied. It is determined that the performance characteristics of flexible thermal insulation materials are in direct proportion to the degree of porosity of the constituent materials and their structural characteristics. Shown that the increase in the operating temperature of these materials, sound and thermal resistance is determined by the chemical and mineralogical composition of the source materials and their structural characteristics. The influence of the mechanism of selective leaching of coarse continuous basalt fibers on their textural characteristics and the zone of operating temperatures is studied.Документ Production of modified basalt fibre for heat-insulating products manufacturing(IOP Publishing, 2019-12) Gots, V. I.; Berdnyk, O. Y.; Rogozina, N. V.; Maystrenko, A. A.As a result of the research flexible heat-insulating materials were developed based on basalt fiber with increased effectiveness, which can be achieved due to directed fiber microstructure forming through fusion modification. It is known that chemical composition of initial fusion not identically influences on physical and chemical and mechanical properties of basaltic fibres. Structural descriptions of fusion and basaltic fibre got from him appear main factors the nearer, than high speed of cooling. This index mainly depends on such constituents: а) ambient temperatures; b) coefficient of heat conducting; c) heat conducting of fusion; d) areas of surface. By researches influence of temperature of basaltic fusion was shown on the structure of fibres. Structural characteristics of the basalt fiber (number of active zones, coefficient of its distribution on the basalt fiber surface, as well as a correlation of three groups of active zones) depend on rheological properties of basal fusion, speed of drawing through the die plate and cooling speed.Документ Radiation protective properties of fine-grained concretes and their radiation resistance(IOP Science, 2020-09-10) Anopko, Dmytro; Honchar, Olga; Kochevykh, Maryna; Kushnierova, LiliyStudies have shown that the thickness of the half layer of the gamma radiation flux attenuation with E = 662 keV is 3,5-5,2 cm (depending on the concrete density average) and for a neutron flux with E = 2,5 MeV is 5-6 cm. The radiation resistance of concrete under the influence of gamma radiation large doses, their activity and radionuclide composition after irradiation with neutrons was investigated. To study the behaviour of concrete under the influence of gamma radiation, two series of samples were made. One series was the control, and the second was exposed to gamma radiation. Its value corresponds to the dose that concrete can receive when it comes into contact with highly radioactive wastes from the “Shelter” facility for 300 years.
- «
- 1 (current)
- 2
- 3
- »