The features of heat and mass transfer through external enclosure structures with capillary - porous material, which are not taken into account in the norms of thermal protection of buildings, are considered. Such features more often occur in buildings with a long service life because of the increasing heat loss, caused by the violation of the terms of repair for a long time. For structures, located in the lower part of the building and having little resistance to air penetration, a calculation model is considered to determine the value of the economizer effect and the saving of thermal energy in conditions of cold air infiltration. The developed model clearly demonstrates, that for two - and twelve-story houses the saving of thermal energy, as a result of the economizer effect, is about 3% and 10% respectively. A computational model of exfiltration of warm air through similar structures, located in the upper part of the building, is proposed. An additional value of heat loss during exfiltration of the warm air from the rooms is determined, using an example of old building with a wooden floor of a cold attic and bulk insulation in the absence of layers with high resistance to air penetration. This value is 3.5 times higher, then that determined by the standard method, which does not take into account the redistribution of cold and warm air densities along the height of the building. This leads to a deterioration of the indoor climate and an increase in heat loss. By calculation, the dependence of the value of heat losses on the total thermal resistance of the attic floor and on the number of floors was established. A number of measures, aimed at improving the energy efficiency of existing residential buildings, are proposed, such as laying a vapor barrier layer and an additional layer of effective thermal insulation on top of the bulk insulation as part of the attic floor and installing a cement-sand screed for this insulation.
The studies of the processes of structure formation and formation of properties of light ceramics with a density of 450...1200 [kg/m3] are presented. There were determined the regularities of the effect of modifiers on the deformation and strength characteristics of siliceous ceramics.
Studies of the influence of vibration impact on the strength of foam-ceramic raw material, produced on the basis of chemically modified natural silicites, are presented. The natural oscillation frequencies of mineral particles are established, taking into account their size, density and ultimate shear stress of raw suspensions. It is shown that the coincidence of the natural and forced oscillations of the particles leads to an increase in the thixotropic effect. Using the technology of a controlled «sol-gel» transition in the structure of raw material, swelling under the influence of vibration load, samples of the material were obtained with a higher-quality macrostructure without the use of binders. Indicators of compressive strength and average density of raw and ceramics are given.
Influence of exometabolites of Bacillus cereus strain microorganism on cement mortar properties was studied. According to the strength criterion, the optimal dosages of the bioadditives and the order of its introduction into the solution are established. The description of the mechanism of formation of the effect of bio-cementation is given.
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