×

You are using an outdated browser Internet Explorer. It does not support some functions of the site.

Recommend that you install one of the following browsers: Firefox, Opera or Chrome.

Contacts:

+7 961 270-60-01
ivdon3@bk.ru

  • On the dependence of "stress-strain" and "modulus of strain-loading level" for concretes with organomineral modifiers

    It is shown that the given ratio of the modulus of deformation and the initial modulus of elasticity of concrete depends not only on the type of the function ε = f(𝜎), and from the initial modulus of elasticity of the concrete, i.e. concrete with different values of initial modulus at equal strength, for example, with the introduction of the composition of concrete organo-mineral modifiers, the dependence of the ratio E𝜎/E0 from the loading level will vary. To describe the "stress-strain" or "modulus of deformation-level of loading" for concretes with organo-mineral modifiers, it is advisable to use The sargin diagram, taking into account the influence of modifiers on the main deformation constants: the initial modulus of elasticity, the coefficient of elasticity, the relative deformation corresponding to the short-term strength limit. The nature of deformation of concretes with organo-mineral modifiers at a loading level above 0.9 may differ from the known patterns for traditional concretes, in connection with which this issue requires special study.

    Keywords: modulus of deformation, stress-strain diagram, modified concretes, loading level, modulus of elasticity

  • On the question of assessing the frost resistance of concrete on the strength criterion

    Durability of concrete, including fine-grained, with alternating cyclic temperature effect of the external environment is normalized according to GOST 26633 mark on frost resistance, and frost resistance criterion for all concrete in accordance with GOST 10060-2012 is the ratio of ultimate strength on compression of the main and control samples not less than 0.9 with a coefficient of variation of strength in the series, while for concrete road and airfield pavements is another additional criterion is the loss of mass. In the previous edition of GOST 10060, the ratio of the compressive strength of the main and control samples not less than 0.95 was adopted as the criterion of frost resistance for all concretes. GOST 31357 normalizes the indicator "frost resistance of the contact zone" for a number of mortars or fine-grained concretes obtained from dry building mixtures. This indicator characterizes the ability of the solution or fine-grained concrete to maintain the strength of adhesion to the concrete base after a certain number of freeze-thaw cycles. For the brand for frost resistance of the contact zone from Fkz25 to Fkz100, the number of cycles is taken, after which the decrease in the adhesion strength to the base does not exceed 20% according to GOST 31356, and in this case the coefficient of variation of the clutch values measured in the series is not taken into account. Due to the limited information on the change in the in-series coefficient of variation of strength after cyclic freezing-thawing, as well as the ratio of frost resistance by the criterion of compressive strength and adhesion strength to the base, the purpose of this study was to identify patterns of change in the in-series coefficient of variation of strength and adhesion strength to the base of fine-grained concretes obtained from dry building mixtures based on various Portland cements with the content of various redispersible polymer powders from 0 to 3%. The studies were carried out on the basis of 75 freeze-thaw cycles. This paper presents the results on the change in the coefficient of variation of strength after cyclic freezing-thawing and the ratio of frost resistance coefficients

    Keywords: frost resistance of concrete, coefficient of variation of strength, coefficient of frost resistance, fine-grained concrete, dry mixes

  • Calibration of machines with numerical program control by means of a laser tracker of VINTAG

    Results of the performed works at calibration of the metal-cutting machine are given in article. The technology of performance of control is considered. The conclusion in which it is noted that laser trackers including the measuring Vintag vehicle produced by Faro firm, possess high efficiency of the solution of problems of calibration is made. Their software has an opportunity to carry out processing of results of measurements and preparation of reports directly on the platform of performance of work and to give results on the place. To provide the accuracy of measurements of the spatial coordinates of 0.005-0.01 mm at distances to 10000-15000 mm. All these characteristics allow to recommend to machine-building enterprises use of such and similar measuring cars for the solution of problems of calibration of metal-cutting machines.

    Keywords: Laser trekker, measurements, geometrical parameters, straightforwardness, perpendicularity, metrology, calibration, metrological characteristics

  • Methods of formation of professional competence of students of the specialty 08.03.01 Construction

    the Basic meaning of the content of the article is to reveal the formation of professional competence of students of higher education construction professions on the example of a business game. Business game "facade" is the functional-architectural meeting ambitious designers" was held under the second course in the discipline "Construction materials". The essence of this method is that students demonstrate certain production situation, which is characterized by conditions and actions of its participants. The task is to find the best modern methods of construction technologies. As a rule, the production situation in construction occur on the object, in our game object – the building of the Palace of culture, which was commissioned 10 years ago. During the operation of the building facade cladding in some places, damaged, cracks, and loose tiles. It was necessary to find the right solution for the replacement of the cladding material, to previously conduct a survey and identify the cause of the damage. For this group of students was divided into subgroups and each defined role. Each of the groups in the course of a game functioned, however, all must understand by simulating the situation and content of the actions of other groups. The problem was the following, as a preliminary survey of the damage to the facade of the object (performed measurements, photos, samples provided to the facing surfaces of the facade), it was necessary to establish the cause of the damage and propose the most optimal, effective and meets all the architectural, technological, technical and economic requirements methods of eliminating damage.the new enterprises, redistribution of investments in interests of the organization and development of new production on available floor spaces. The most important organizational economic targets of a diversification of management are presented by innovative activity of the industrial enterprise.

    Keywords: ompetence, tudents, nhe business game, research, the industrial situation, building materials and products.

  • Definition carbide component coatings made subsonic and supersonic gas-powder surfacing

    The quantity of carbide component in the deposited coating made subsonic and supersonic gas-powder surfacing. The investigations, which revealed that the preferred method is a supersonic gas-powder surfacing in the lower position.

    Keywords: supersonic gas-powder cladding, carbide component, protective coatings, subsonic gas-powder cladding microstructure