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  • The study of the change in the composition of a concrete mixture and kinetics of concrete strength during centrifugation on the example of the production experience of power line supports at the enterprises of the Socialist Republic of Vietnam

    The experience of applying centrifugation as a molding and compacting method has opened new prospects for the production of highly efficient reinforced concrete products. The experience of production of centrifuged power line supports at one of the enterprises of the Socialist Republic of Vietnam is analyzed. The studies aimed at studying the change in the composition of the mixture during centrifugation and the kinetics of the strength of centrifuged concrete were carried out. The dependence of the ultimate strength of centrifuged concrete on compression on the value of B / W after HMT (heat and moisture treatment) and at the age of 3-7 days was studied. Conclusions are made on the correction of the known quantitative regularities of the change in the strength of vibrating concrete from the value of B / W and the porosity, taking into account the heterogeneity of the structure of the centrifuged concrete over the cross section.

    Keywords: centrifugation, heavy concrete, concrete mixture, power line supports, additives to concrete, enterprises for the production of reinforced concrete products

  • Deformation properties and parametrical points of concretes of frame structure

    The peculiarities of the deformation diagram under short-term central axial compression of concrete of the frame structure of class B60, obtained by immersing a large aggregate in a low-viscosity solution component, are revealed. The boundaries of microcrack formation of concrete are determined. A good correspondence of the main regularities of the change in the tensile strength and deformation properties of a concrete frame structure with some known data is shown. The possibility of an analytical description of the deformation diagram of a concrete frame structure known formula Sargine (Sargine) is confirmed. Data are presented on the change in the initial modulus of elasticity, the Poisson's ratio, the change in the volume of concrete and the propagation velocity of ultrasound in concrete, depending on the level of loading. The ratio of cubical and prismatic strength is given. The conclusion is made about the expediency of using concrete frame structure in reinforced concrete columns.

    Keywords: concrete frame structure, tensile strength, modulus of elasticity, deformation diagram, parametric points, microcrack formation, superplasticizing additive

  • Pulsed laser deposition of ZnO nanostructures

    The arrays of ZnO nanorods were obtained on the sapphire substrates by means of pulsed laser deposition under the high pressure of argon. The conditions of synthesis were optimized, and their influence on the morphology of  ZnO nanostructures were revealed. It is shown that the concentration of oxygen vacancies in ZnO nanorods can be changed by regulation of the synthesis temperature from 850 to 915 °. This process can be controlled by the ratio of intensities of the photoluminescence emission in the visible and ultraviolet regions. So, it allows to create nanostructures for UV photodetectors or chemosensors depending on the temperature choice.

    Keywords: ZnO nanorods, laser deposition, PLD, photoluminescence

  • The influence of some water-repellent additives on the change in the strength of cement stone

    The article briefly describes the history пояявления hydrophobic cements. Considered one of the прспективных directions for the use of water-repellent additives today - in the dry construction mixtures and confirmed the significance of this direction. The article describes the results of experiments on the impact on the indicators of a cement-sandy solution additives series GMI and the analysis of the received data  

    Keywords: hydrophobic cement, hydrophobic additives, dry construction mixtures, porosity of a cement stone, strength cement-sandy solution, involving air, antifoam, antifoam agent

  • the dependence of the column’s relatively carrying capacity on the relatively eccentricity

    "The results of the computational experiment, Show, that the dependence of the relatively carrying capacity on the relatively eccentricity is almost independent on the reinforcement Ratio or on and concrete type. "

    Keywords: High- Strong concrete, self-compacting concrete, modulus of elasticity, column.