Будівництво та цивільна інженерія

Постійний URI для цього зібранняhttps://repositary.knuba.edu.ua/handle/987654321/1219


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  • Документ
    Intumescent fireproof coatintgs based on zeolite-like cement matrices
    (Wiley, 2023-09) Krivenko Pavel; Guzii Sergii; Rudenko Igor; Konstantynovskyi Oleksandr
    Concrete and reinforced concrete building structures (for example, such as tunnels) lose carrying ability in case of high‐temperature fire action. The aim of the research is to study the prevention of reinforced concrete structures (for example, such as tunnels) under fire action in case of using the proposed coating based on the alkaline aluminosilicate binder, which would not consist of organic components dangerous to health. The ratios between constituent oxides in the binder which ensure the ability to bloat the coating under fire action were determined. The performance properties of developed fire protective coating were defined after artificial aging (cycles of alternate drying and cooling) and fire action: bloating factor ‐ 2.0…5.1, adhesion strength ‐ 6.6…8.0 MPa, compressive strength ‐ 2.3…4.5 MPa, cohesive strength of 1.2…1.5 MPa, thermal conductivity coefficient ‐ 0.042…0.066 W/m‐°C, total porosity ‐ 92…97 %. The temperature at which the coating starts to bloat = 200…250 °C has been developed. The results of the test held in the open air suggested drawing a conclusion that with a coating thickness of 6 mm protection of the reinforced concrete from fragile fracture and from plastic deformations in the metal of the reinforcement they provided under fire exposure for a period of 3 hours.
  • Документ
    Feasibility of incorporating SO42--ions in zeolite-like matrices based on alkaline aluminosilicate binders
    (Elsevier BV, 2023-08) Krivenko, Pavlo; Rudenko, Igor; Konstantynovskyi, Oleksandr; Vaičiukynienė, Danutė
    Factors determining minimization of the influence of sulfate environments on concrete and risk of corrosion of embedded steel reinforcement have been analyzed. Coatings based on alkaline aluminosilicate binders were proposed to prevent transport of the sulfate ions into concrete. The formation of water resistant zeolite-like matrices on the alkaline aluminosilicate binder of the Na2O-K2O-Al2O3-SiO2-H2O system at 20 ± 2 ◦C can be provided by the use of calcium-containing modifying additives. Optimized molar ratios between oxides of binder constituent were SiO2/Al2O3 = 4–5 and K2O/(Na2O + K2O) = 0.15–0.30. The results of the study show that the speed of incorporating sulfate ions in cement matrix of binder from the sulfate environment is dependent upon a cation and ranks as follows: (NH4)2SO4 > MgSO4 > Na2SO4 > CaSO4. Complete protection of concrete against the penetration of sulfates can be reached when the developed coating is applied in a thickness of 3 mm.
  • Документ
    Effect of sodium phosphate and sodium nitrate on microstructure of alkali-activated slag cement pastes and properties of reinforced concrete under cyclic drying-wetting in sea water
    (AIP Publishing, 2023) Krivenko P.; Rudenko I.; Konstantynovskyi O.; Boiko O.; Vaičiukynienė D.
    The relevance of alkali activated slag cement (AASC) concretes for marine structures is due to their enhanced resistance to sea water. However, cyclic influence of sea water and drying under the action of atmospheric carbonic gas in actual operating conditions cause risks of both deterioration of concrete and corrosion of steel reinforcement. These risks increase in case of fresh concretes with high consistency. Application of salts of strong acids, i.e. sodium phosphate and sodium nitrate, in combination with complex multifunctional additive «portland cement - alumina cement - clinoptilolite» was proposed to protect plasticized AASC concrete from the influence of cyclic drying-wetting in sea water with combination of exposure classes XC4 and XS3. It was shown the advanced crystallization of AASC microstructure due to the mentioned salts as admixtures. Corrosion resistance potential of AASC concrete can be improved due to application of specified salts in combination with the mentioned complex additive as factor of aggressive ions (Cl-, SO42- and CO32-) binding. The modified in proposed way plasticized AASC concrete was characterized by the advanced performances, i.e. pore structure, structural density, strength, corrosion resistance, state of steel reinforcement after 90 cycles of wetting/drying in sea water.
  • Документ
    Comparison of influence of surfactants on thermokinetic characteristics of alkali-activated slag cement
    (Private Company Technology Center, 2021-11-26) Krivenko Pavlo; Rudenko Igor; Konstantynovskyi Oleksandr
    Increasing the durability of concrete and reinforced concrete structures according to the criterion of crack resistance is a relevant task of construction materials science. To solve this task, this paper proposes effective solutions for adjusting thermofinite characteristics of alkali-activated slag cement (ASC) by using surfactants of various chemical nature in order to control the thermally-stressed state of concrete based on it (ASC concrete). The method of calorimetry was applied to show that the problematic issue is to adjust the structure formation of ASC by anion-active surface-active substances based on complex polyesters. This is predetermined by the instability of the molecular structure of surfactants in the hydration environment of ASC due to the destruction of complex ester bonds as a result of alkaline hydrolysis. Thermokinetic analysis has demonstrated the effectiveness of using anion-active surfactants, which do not contain ester bonds, as regulators of crack resistance of ASC concrete. Simple polyesters and multi-atom alcohols provide the ability to adjust the duration of the induction period while ensuring the required completeness of ASC hydration within a time frame. The effectiveness of cation-active surface-active substances has been shown, which are characterized by the stability of the molecular structure in the hydration environment of ASC and an increased level of adsorbing capacity. The decrease in the effectiveness of surface-active substances has been shown, in terms of the effect on the heat release of ASC, in the following series: alkaline salt of carboxylic acid>salt of the quaternary ammonium compound>simple polyester> polyalcohol>complex polyester. The reported results are important in view of the possibility of effective adjustment of ASC heat release by influencing the structure formation of surfactant with a certain molecular arrangement in order to predictably reduce crack formation in a thermally-stressed state and a corresponding increase in the durability of structures.
  • Документ
    Design of slag cement, activated by Na (K) salts of strong acids, for concrete reinforced with steel fittings
    (Private Company Technology Center, 2020-12-31) Kryvenko Pavlo; Rudenko Igor; Konstantynovskyi Oleksandr
    This paper proposes a technique to prevent the corrosion of steel reinforcement in concrete based on slag cement (SC) activated by Na(K) salts of strong acids (SSA) in the composition of by-pass cement kiln dust (BP). The technique implies using additional modifiers in the form of the Portland cement CEM I 42,5 R and the calcium-aluminate admixture (CAA) С3А∙6H2O. It is shown that adding the Portland cement contributes to enhancing the intensifying influence of BP on the SC hydration, accompanied by an increase in the strength of artificial stone. This effect is predetermined by the formation of hydrosilicates in hydration products with an increased crystallization degree in the form of CSH(I) and C2SH(A). Modifying SC with CAA ensures the intensive formation of low-soluble AFm phases in the composition of hydration products, aimed at reliable binding the SSA anions (Cl-, SO42-) that are aggressive to steel reinforcement. The study result has established the possibility to produce SC, activated by SSA, when using BP, the Portland cement, and CAA. Mathematical methods to plan the experiment were applied to produce an SC composition of "granulated blast furnace slag – BP – Portland cement – CAA", characterized by a strength class of 42.5 and a molar ratio of Cl-/OH- in a porous solution not exceeding 0.6. The resulting properties predetermine the feasibility of using SC in steel-reinforced concrete. The relevance of this work is due to the modern trends in the development of the construction industry. The introduction of cement that contains mineral additives, in particular granulated blast furnace slag, contributes to improving the environment by reducing СО2 emission. The use of such cement as a base of steel-reinforced concrete ensures the increase in their functionality and durability.
  • Документ
    Elements of technology for the surface gipsum composite and its properties, as a facing material
    (ОДАБА, 2022-03) Tarasevych, V. I.; Gasan, Yu. G.
    The paper considers the issues of obtaining a composite material based on gypsum, fly ash and sulfur with improved performance. Regularities of impregnation of a gypsum sol matrix with a sulfur melt are established, taking into account the capillary-porous structure of the gypsum sol stone and the physical and technical properties of sulfur. The conducted studies make it possible to determine the sulfur mass transfer coefficient ams and the maximum sulfur-containing Us in impregnated products, depending on the initial values of the sulfur melt temperature, water-solid ratio and fly ash content. This allows to determine quickly and effectively the duration of impregnation to a given sulfur content for a specific composition and size of gypsum products. Technological factors influencing the hardening coefficient, water resistance and chemical resistance of gypsum ash products impregnated in sulfur melt have been studied. An analysis of the results shows that the strength of samples impregnated with sulfur increases while the degree of filling of the pore space with it is increasing. So, with increase in the relative sulfur content (v = Us / Usmax) from 0.30 to 0.90, the compressive strength increases from 10.1 to 42 MPa. It has been established that water resistance of the impregnated samples significantly depends on the degree of impregnation and the amount of fly ash. The experiments carried out give reason to believe that the material based on gypsum, ash and sulfur refers to waterproof materials, since the softening coefficient is higher than 0.7. It has been established that gypsum and gypsum samples impregnated with sulfur melt have a chemical resistance coefficient of at least 0.7, which allows them to be classified as chemically resistant. The resulting sulfur-gypsum composite is distinguished by high strength, water and corrosion resistance to aggressive environments of livestock complexes, food and chemical industries, where it should be used in the form of special facing products. В роботі розглянуті питання отримання композиційного матеріалу на основі гіпсу, золи-виносу та сірки з підвищеними експлуатаційними характеристиками. Встановлено закономірності просочення гіпсозольної матриці розплавом сірки з урахуванням капілярнопористої структури гіпсозольного каменю та фізико-технічних властивостей сірки. Проведені дослідження дозволяють визначати коефіцієнт масопереносу сірки ams та максимального сірковмісту Us у просочених виробах, залежно від вихідних значень температури розплаву сірки, водотвердого відношення та вмісту золи-виносу. Це дозволяє ефективно та оперативно визначати тривалість просочення до заданого вмісту сірки для конкретного складу та розміру гіпсозольних виробів. Досліджено технологічні фактори, що впливають на коефіцієнт зміцнення, водостійкість та хімічну стійкість гіпсозольних виробів, просочених у розплаві сірки. Аналіз результатів показує, що міцність просочених сіркою зразків підвищується зі збільшенням рівня заповнення нею порового простору. Так, при збільшенні відносного вмісту сірки (v= Us/Usmax) з 0,30 до 0,90 межа міцності при стисканні підвищується з 10,1 до 42 МПа. Встановлено, що водостійкість просочених зразків істотно залежить від ступеня просочення та кількості золивинесення. Проведені експерименти дають підставу вважати, що матеріал на основі гіпсу, золи та сірки відноситься до водостійких матеріалів, оскільки коефіцієнт розм'якшення вище 0,7. Встановлено, що гіпсові та гіпсозольні зразки, просочені розплавом сірки, мають коефіцієнт хімічної стійкості не менше 0,7, це дозволяє віднести їх до хімічно стійких. Отриманий сіркогіпсовий композит відрізняється високою міцністю, водо- та корозійною стійкістю до агресивних середовищ тваринницьких комплексів, підприємств харчової та хімічної промисловості, де його слід використовувати у вигляді спеціальних облицювальних виробів. Ключові слова: сірка, гіпс, зола, водостійкість, хімічна стійкість, розплав сірки.
  • Документ
    Корозійностійкий облицювальний матеріал з серогіпсового композиту
    (УДУЗТ, 2021-11) Тарасевич, Віталій; Гасан, Юрій
    Ефективним способом підвищення водостійкості й покращення інших будівельно-технічних властивостей капілярно-пористих будівельних матеріалів, зокрема й на основі гіпсу, є їх просочення речовинами, здатними тверднути в поровому просторі цих матеріалів, що сприяє ущільненню структури й перешкоджає проникненню в них вологи.
  • Документ
    Оптимизация технологии получения серогипсового композита
    (ОДАБА, 2021-05) Тарасевич, В. И.; Гасан, Ю. Г.; Долгошей, В. Б.
    Эффективным способом повышения водостойкости и других строительно-технических свойств капиллярно-пористых материалов, в том числе и на основе гипса, является пропитка веществами, способными отвердевать в поровом пространстве этих материалов, что способствует уплотнению структуры и препятствует проникновению в них влаги. The paper considers the issues of studying the structure formation of binders during hardening to determine the optimal moments of mechanical action on gypsum concrete specimens, which makes it possible to optimize the technology of their impregnation with sulfur melt.
  • Документ
    Features of quantitative measurements of the dynamic module of elasticity of binders in optimization of production technology serogypsum composite
    (ОДАБА, 2021-06) Tarasevych, V. I.; Gasan, Yu. G.; Dolgoshey, V. B.
    The paper considers the issues of studying the structure formation of binders during hardening to determine the optimal moments of mechanical action on gypsum concrete specimens, which makes it possible to optimize the technology of their impregnation with sulfur melt. The time dependence of the elastic modulus of a hardening, binder is its important physicochemical characteristic, since it is used to objectively identify the stages of structure formation, to simulate the processes occurring at each of the stages. It is noted that the method of acoustic resonance of bending vibrations, in the case of hardening binders, needs correction with respect to the measurement technique and interpretation of the results obtained. The kinetics of the resonance frequency of a sample consisting of a rigid cell and a dispersion poured into it is a function of the elastic properties of the cell, the dispersion itself, the contact zone of the dispersion with cell and therefore cannot be used for either qualitative or quantitative analysis of the kinetics of hardening. Taking into account the elasticity of cuvette is necessary to obtain reliable information. В роботі розглянуті питання дослідження структуроутворення в’яжучих в процесі тверднення для визначення оптимальних моментів механічної дії на гіпсобетонні зразки, що дозволяє оптимізувати технологію їх просочування розплавом сірки. Часова залежність модуля пружності твердіючого в’яжучого є його важливою фізико-хімічною характеристикою, оскільки вона використовується для об’єктивного виділення етапів структуроутворення, моделювання процесів, що протікають на кожному з етапів. Відмічається, що метод акустичного резонансу, у випадку твердіючих в’яжучих, потребує корекції відносно методики вимірювань та трактовки отриманих результатів. Кінетика резонансної частоти зразка, що складається з жорсткої кювети і залитої в неї дисперсії, є функцією пружних властивостей кювети, самої дисперсії, зони контакту дисперсії з кюветою і тому не може бути використана ні для якісного, ні для кількісного аналізу кінетики твердіння. Врахування пружності кювети є необхідним для отримання достовірної інформації.
  • Документ
    Processes of structure formation and neoformation of basalt fiber in an alkaline environment
    (IOP, 2020) Berdnyk, O. Yu.; Lastivka, O. V.; Maystrenko, A. A.; Amelina, N. O.
    Several approaches can be used to determine the effect of an alkaline environment on glass materials (basalt fibers). One of the most common approaches for the determination of the alkali resistance of a substance is to measure the relative mass loss after the interaction of the object of research with the alkaline environment. According to the practice guidelines, the approach involves determining the alkali resistance of a glass by measuring the mass loss per unit area of the glass under test after boiling it in an alkaline solution. But the disadvantage of this approach is it can’t be applied to basalt or another multicomponent fiberglass as it doesn’t introduce different speeds of fiber dissolution.