"Вестник МГСУ"

The problem of the most accurate estimation of energy consumption by ventilation and air conditioning systems in buildings is a high-priority task now because of the decrease of energy and fuel sources and because of the revision of building standards in Russian Federation. That’s why it is very important to find simple but accurate enough correlations of the climatic parameters in heating and cooling seasons of a year.Therefore the probabilistic and statistical relationship of the parameters of external climate in warm and cold seasons are considered. The climatic curves for cold and warm seasons in Moscow showing the most probable combinations between the external air temperature and the relative air humidity are plotted using the data from the Design Guidelines to the State Building Code “Building Climatology”. The statistical relationship of the enthalpy and the external air temperature for climatic conditions of Moscow are determined using these climatic curves and formulas connecting relative air humidity and other parameters of the air moisture degree.The mean value of the external air enthalpy for the heating season is calculated in order to simplify the determination of full heat consumption of ventilating and air conditioning systems taking into account the real mean state of external air. The field of ap- plication and the estimation of accuracy and standard deviation for the presented dependences are found. The obtained model contains the only independent parameter namely the external air temperature and therefore it can be easily used in engineering practice especially during preliminary calculation.

The construction quality of road surface of non-rigid type essentially depend on providing the temperature regimes in the process of laying and packing of hot asphalt concrete mixtures. In order to provide the required characteristics of asphalt concrete due to the surface width it is necessary to provide the temperature regimes of hot asphalt concrete mixture in the zones of lane connection. The hot mixture is promptly cooling right after laying within several minutes, which results, according to the construction technology and the specific conditions of work production, in temperature abuse of the mixture at joints of the lanes at packing. The authors present the analysis of the technology of arranging multilane road surface by one paver with the possibility of heating the surface lane edge with the temperature of the adjacent lane. The results of the studies of the production conditions effect on the temperature of edge heating of the previously laid lanes, and the time required to achieve the maximum heating temperature depending on the relative thickness of coating layers.

Recently the requirements to the high quality of works for critical groups of buildings are more rigid in Russia. This also concerns the transport structures, which play the key role, such as bridges, tunnels, overpasses and other similar facilities. Particularly high requirements for these structures are: reliability, frost resistance, water resistance, crack resistance and durability. In this article the main principles of providing high consumer properties of these objects are highlighted. Modern achievements in concrete researches are used, which are based on scientific studies performed in JSC CNIIS.The main problem in the process of concrete curing is not only in thermostressed state, which depends on the temperature and on the features of structure formation related to the changes in temperature regime of hardening concrete. The service properties of concrete are also influenced by different kinds of thermal stresses, occurring during concrete hardening: submicrostresses, microstresses and macrostresses. A special role in the theory of concrete hardening is played by the so-called own (or residual) thermal stress, which increases or decreases fracture of constructions. With the help of the accounting for these types of thermal stresses, the author shows how to increase crack resistance of concrete constructions without use of extra means of protection from temperature cracks. Furthermore, the author vividly shows, how to consider the magnitude of the temperature drops properly, which occur in concrete and lead to the formation of residual thermal stresses. The research of thermal stresses helps to reduce the cost of the device for additional thermal insulation of concrete, and to achieve high consumer properties of a construction. Positive results from the performed work were used in the construction of a number of transport tunnels in the city of Moscow, which led to the acceleration of their construction and reduced the cost of providing perfect quality of performed works.

The article covers the formation of the pore structure of cement systems that harden at low and negative temperatures. Temperature fluctuations that accompany the hydration of cement systems can produce a substantial impact onto the chemical activity of the water in the course of hydration. These factors can produce an adverse impact on the formation of the structure of the cement stone and impair its performance characteristics. The formation of the structure of cement systems is dependent on the impact of specialized additives, including antifreeze agents that facilitate hydration at low and negative temperatures. The research of their action and the nature of their influence on the formation of the microstructure of the cement stone facilitate the purposeful adjustment of their properties. Therefore, modification of cement systems by specialized antifreeze components is a relevant objective of scientific and practical research.
Research of a classical cement system (a benchmark composition) and a cement system modified by a specialized antifreeze polymer-based additive (a modified composition) was performed to identify the impact of antifreeze additives onto the process of formation of its pore space.
Upon completion of the research project described in the article, the authors have concluded that antifreeze additives facilitate hydration of cement at low and negative temperatures and cause regular formation of the pore structure of the cement stone.

The authors argue that the use of pyrometers can be recommended for a limited number of
tasks. The method of spectral brightness conversion proposed by the authors serves as the founding
principle of a universal measuring device that has a low rate of errors. This method is effective
at different wavelengths.
The number of errors is reduced two-fold: first, the number of instrument-related errors is
reduced through increasing the sensitivity of the pyrometer and identifi cation of the finest pyrometry
ratio. Second, the authors suggest using, at least, three effective wavelengths to register the
spectral brightness. Moreover, the authors believe that the reduction of the systematic error of the
measured optical transition temperature designated for the derivation of its genuine values requires
the right choice of an effective wavelength so that the equivalent wavelength of the double spectral
ratio became infinitely big. This methodology makes it possible to derive an independent pyrometry
equation to identify unknown emissivity factors within three wavelengths. Thus, the pyrometric system
does not only take different temperature measurements, but also serves for the simultaneous
determination of monochromatic emissive power in the online mode, which is essential for the purposes
of taking measurements in the course of production of construction materials.

Introduction. Energy and hydraulic concrete structures, bridge structures, foundations of buildings are built with concrete blocks. Concreting of such massive structures is accompanied by the phenomenon of exothermic heating of the structure caused by the process of cement hydration. The heat released in such massive blocks under natural conditions is very slowly removed from the structure. Quite often, between the central part of the massif and its surface, there is a significant temperature drop. In the case of reaching a critical value of the temperature difference, temperature cracks occur that violate the solidity of the structure. For a preliminary assessment of the possibility of cracking and the development of measures to eliminate it, it is necessary to solve the temperature problem and the problem of determining the thermal stress state. This problem has long been in the center of attention of specialists and a large number of studies are devoted to it. Developed and used a large number of methods for solving these problems. However, in view of the great complexity of the task to be solved, caused by a multitude of operating factors and conditions, the complexity of the structures and the increased requirements for the safety of structures, the task of determining the temperature regime and the thermally stressed state of the erected concrete massif is still very relevant today. This paper presents some results of investigations in this direction, performed on the basis of the finite element method. An erected concrete block is considered, for which a non-stationary temperature problem is solved successively and the resulting temperature stresses are determined. The variants of block laying at different external temperature influences are considered. Materials and methods. The study was performed on the basis of the finite element method (FEM) using the Ansys software. Results. For the considered array concrete obtained temperature distribution and thermal stresses over time from the moment of packing to obtain a sufficient structural strength (about 30 days). On the basis of criteria assesses the possible occurrence of thermal cracks. Conclusions. Based on the numerical solution of the problems of determining the temperature regime and the thermally stressed state of the concrete block using the Ansys software complex, a detailed picture of the spatial no stationary state of the structural element, the concrete block, as part of a massive structure, has been obtained.

The article covers the concepts, definitions and correlations of parameters of worn surfaces
within the coordinate system of relative pressures and convergences of interacting elements of
construction machines.
The authors provide their findings based on the research of microtopographic and tribological
engineering parameters of scoop hinges of construction drags and fused crushing plates of jaw
crushers. As for the drag hinges, the friction pair is to include steel 110Г1ZL and X-5 padding that
demonstrates high resistance to friction (=1.04) and low temperature of frictional heating (ƒ= 90
°C). Mobile plates of jaw crushers need electrodes VSN-9 and TsN-16 for padding purposes, as they
demonstrate the biggest frictional fatigue values (= 2.76 and 2.62, respectively) and insignificant
temperature of heating of friction surfaces (9.4 and 4.9 °C). Electrodes TsN-16, T-590 and KBKh-45
are recommended for fixed plates.
Microtopographic parameters of worn friction surfaces are used to analyze the main tribological
engineering parameters of operating elements and joints of construction machines and items of
equipment.

Subject of research: the main heat loss occurs through the building fence. In the paper, the object of research is enclosing structures with different thermal conductivity. The problem of moisture accumulation in the wall is quite relevant. One of the main problems in construction is saving on building materials and improper design of building envelope. This in turn leads to a violation of the heat and humidity regime in the wall. This paper presents one of the methods to address this issue. Purpose: description of heat and humidity conditions in the wall fence of high-rise buildings. It is also necessary to analyze the relationship between the thermophysical characteristics. Materials and methods: the temperature distribution in the layers will be analyzed on the basis of the structure consisting of 10 layers; the layer thickness is 0.05 m. Materials with different thermal conductivity were used. Each subsequent layer differed in thermal conductivity from the previous one by 0.01. Next, these layers are mixed. The calculation of the humidity regime includes finding the temperature distribution along the thickness of the fence at a given temperature of the outside air. The quality factor of the temperature distribution is the maximum average temperature. This research are conducted in the field of energy efficiency. Results: the higher the average wall temperature, the lower the air temperature differs from the wall temperature. In addition, the higher the average temperature of the wall, the drier the surface inside the wall. However, moisture accumulates on the surface inside the room. The working capacity of multilayer enclosing structures is determined by the temperature distribution and distribution of moisture in the layers. Conclusions: moisture movement through the fence is due to the difference in the partial pressure of water vapor contained in the indoor and outdoor air. A layer with minimal thermal conductivity should be located on the outer surface of the wall in a multi-storey building. The maximum change in the amplitude of temperature fluctuations is observed in the layer adjacent to the surface by periodic thermal effects. It is also taken into account that the process of heat absorption has a great influence on the temperature change in the thickness of the wall fence to the greatest extent within the layer of sharp fluctuations (outer layer). The Central part of the wall (bearing layer) will be the driest. These calculations are satisfied with the design of the ventilated facade.

Introduction. Were investigated samples of fiberglass with the aim of its effective use in construction in the long term. Fiberglass is considered one of the most versatile and durable materials among polymer composite materials, however, and it is subject to destruction. It is known that one of the main reasons for reducing the specified characteristics and material properties is operational. At the design stage, it is necessary to determine the most reliable and economical materials used and, accordingly, be sufficiently aware of their strength and durability. Thus, in order to avoid the destruction of the material, as well as significantly enhance and prolong its service life, it is necessary to be aware of how exactly the properties of the material change over time. Regarding reinforced concrete, wood, brick and steel fiberglass is used in construction recently. This means that while the service life of the list of the most common materials in construction is known to a sufficient extent, manufacturers do not dare to use fiberglass as a material for critical structures. This occurs because changes in its characteristics, depending on operational factors, are not sufficiently studied for intervals exceeding 4-5 years of operation. Materials and methods. During the work, samples of fiberglass SPPS with a longitudinal and transverse arrangement of fiberglass were tested for climatic aging in a climatic chamber for 5 cycles simulating 5 years of material operation. All samples were subjected to tensile testing on a tensile testing machine R-5. Results. Destructive stresses were determined, calculations were carried out and elastic and strength characteristics of the samples were analyzed. On the basis of the obtained results, an analysis was carried out, conclusions were formulated about the use of fiberglass in the construction in the long term, as well as the influence of such operational factors as moisture, positive and negative temperatures, and ultraviolet radiation on the properties of fiberglass with a different arrangement of fiberglass. Conclusions. Found that the destructive stresses of fiberglass are significantly reduced during the first two years of operation, which must be considered when choosing fiberglass with the stated characteristics. Ultraviolet does not have a significant effect on the elastic-strength properties of the material, while during operat