Abstract: The main drawbacks of aerated concrete preparation traditional technology are considered. The method essence for the porous structure formation of aerated concrete products with variational properties is formulated. The main factors affecting aerated concrete products properties of varying density and strength along the cross-section are indicated. The mold cover closed surface with a circular opening area effect on aerated concrete products main properties is shown and its optimum value is revealed. The traditional and modern types gas generators influence on gas evolution kinetics, mixture swelling height, gas generators stability in time and variable density and strength on the cross-section aerated concrete products main properties are considered.
Abstract: This article considers the possibility of increasing the effectiveness of composite gypsum binders (CGB) by controlling the processes of structure formation as a result of using new types of multicomponent mineral additives that are significantly different from the traditionally used quartz raw materials:- waste of wet magnetic separation of ferrous quartzites (WMS waste,) of polymineral composition with quartzy of varying degrees of crystallinity, nanodispersed silica and chalk powder. We have studied the cause-effect relationship between the change in the ratio of binding and mineral additives of various compositions, which determines the conditions for the formation of technological and strength characteristics of the projected composite materials with specified performance properties. We have established the presence of regularities in the changes in the properties of CGB, the composition of the hardening products and the microstructure depending on the type and content of gypsum binders of β-and α-modifications, portland cement, multicomponent finely-dispersed mineral additives, the regularity consists in the binding of portlandite, which is released upon portland cement hydration, by the amorphous phase of earth siliconas a part ofnanodispersed powder and chalcedony variety of quartz waste of wet magnetic separation of ferruginous quartzites. This provides a reduction in the basicity of the solidifying system, the intensification of crystal formation, and the formation of newgrowths with a high content of tobormorite-low-basic calcium hydrosilicates that compact the microstructure of the hardening matrix and, as a result, increase the water resistance and stability. It is noted that this mechanism of hydration of CGB minimizes inner stresses and volume deformations, therefore the number of microcracks decreases, which leads to an increase in its efficiency in comparison with the traditionally used gypsum binder and that differs from the traditional portland cement by a fast strength generation.
Abstract: The paper deals with change patterns of heat-efficient concrete depending on the content of artificial granulated aggregate and water. The obtained results allow analyzing the quantity and degree of influence of each factor on physical-mechanical properties of concrete and defining its structure.
Abstract: Today concrete is the main material for construction of buildings and constructions and increase in its operational characteristics is a priority problem of modern scientific research acts. This work represents experience of modification of heavy M200 concrete on the basis of local raw materials of Yakutia, with use of polymeric impregnation of "Silor-Ultra" as a result of which data on increase in strength characteristics of material were obtained, the internal structure of the modified concrete was investigated.
Abstract: The paper presents a brief overview of the thin-layer thermal insulation paints used now and their characteristics. A new composition of thin-layer heat-insulation coating is proposed. The introduction of solid phases of non-autoclaved foam concrete with the average density D150 with high values of the standard entropy of formation in it is scientifically substantiated from the point of view of increasing the thermal protection properties. It is shown that such phases have an advantage in comparison with the solid phases of the glass and ceramic microspheres used now. It is also proved that the presence of thin-layer thermal insulation coating of nanoscale particles in the form of silica in the composition favours the reflection of the incident heat flux due to the Tindal effect and provides an increase in the polydispersity of the composition. The calculation of the resulting composition by the Van Vleсk formula used in the classical science is given.
Abstract: In this paper, studies of solid-phase modification of cement systems with organosilicon polymers are presented. Modification of organosilicon polymers was carried out by co-milling clinker and polymers. The number of polymers directly related to cement particles and the features of their adsorption are studied. As demonstrated on the basis of studies of IR spectra, polyorganilsilsesquioxanes and polydiorganosiloxanes participated in chemical interaction with cement systems. Structural characteristics of cement systems (specific surface and particle size), formed during mechanochemical modification, are studied. It is shown that the mechanochemical introduction of organosilicon polymers leads to a significant increase (by 30-60%) of the resistance of cement stone to freezing-thawing in salt solutions.
Abstract: The results of the investigation of phase structural transformations of cement stone as a result of the influence of the aggressive environment of the poultry farm are presented. Analysis of the change in the phase composition of cement stone samples showed that according to the average content of C3S increase in the increase of degree of hydration is represented by the sequence: zone I (air medium with minimal aggression) - zone III (wet environment with maximum concentration of active substances) - zone II (air zone with periodic aggressive action). The degree of carbonization, depending on the test conditions of the samples, is characterized by a similar zonal dependence. In this case, the removal of CaO during the acid leaching of the peripheral regions of the samples was detected to a greater extent during testing in zones II and III.
Abstract: The net shells have unlimited possibilities for creating new architectural forms. The growing number of buildings constructed using this technology indicates the prospects for the use of such structures, especially in harsh climatic conditions and remote areas. The design of reticulated shells is self-supporting and has higher bearing properties compared to other types of structures. This is due to the uniform distribution of loads on all the rods of the structure, which virtually eliminates brittle fracture. The aerodynamic shape of the reticulated shells provides the best wind flow compared to other structures, which makes them stable during destructive hurricanes and tornadoes. The authors set the task to calculate and design the connection swivel node of spatial rod constructions elements; the calculations were carried out in view of geometrical and physical nonlinearity. To that effect, the solid-state model of node was created and numerical simulation was carried out. The computer simulations of the net shells structures, the use of CAD software complexes for automation of activities on stages of design and technological preparation of production are allow to reduce the time of design development, improve the quality and reliability of the design and manufacture of elements.
Abstract: Wood, as a finishing and building material, has always been given special attention. Wood has many positive properties, but it's no secret that faced with its shortcomings such as fragility, instability of form and susceptibility to decay, people often prefer synthetic materials, putting aside the ecology and useful properties of wood and choosing the long life of non-natural materials. In this regard experts around the world are constantly searching for new solutions aimed at improving the physical, mechanical and operational properties of wood, which would allow a person to limit the use of artificially created analogs of natural materials and enjoy the atmosphere of tranquility and appeasement in a house that can create a tree. Analyzing the knowledge and skills of previous generations the author of the article took as a basis various technologies of deep processing with the aim of improving the quality, extending the service life and expanding the scope of its use, thanks to which a new modern moisture resistant "hardened" tree is created for furniture, interior, finishing elements for garden houses and plots. Experiments have been carried out to investigate the biological resistance of wood thermo modified in five different technologies: vacuum-convective thermal modification in a superheated steam, convective thermal modification in a saturated high-pressure steam environment, thermal modification of wood in hydrophobic liquids, thermal modification of wood in a flue gas environment and vacuum-conductive thermal modification. The degree of moisture resistance of the samples is calculated, which makes it possible to conclude that the mass of thermo-modified wood is significantly lower, caused by the destructive effect of fungi, as compared to untreated samples. The most optimal technology for structures involving close contact with water or soil is determined.
Abstract: The stabilizer nature effect on the aggregative stability of the modifying concrete additives based on halloysite nanotubes in the aquatic environment is shown. The chemical composition and morphology of halloysite nanotubes and their additives, obtained by ultrasonic dispersion in the aquatic environment of the surfactant, are studied. The influence on the processes of charge stabilization on the outer and inner surface of halloysite nanotubes is determined. The dependence of nanotube sizes and specific surface area on the stabilizer type, the time of ultrasonic dispersion, and additive storage is revealed. The stabilization mechanisms of aqueous dispersions of modifying additives based on halloysite nanotubes with anion-and cation-active substances are considered. It is established that the polynaphthalenesulfonate-based modifier S-3 has got the maximum efficiency as a stabilizer of aqueous dispersions of modifying concrete additives with halloysite nanotubes.