Abstract: Non-autoclaved aerated concrete is the only viable alternative to gas silicate when organizing its manufacture on the basis of regional small and medium capacity production. This aims to improvement the competitive situation on the building materials market and optimizing the construction costs. The possibility of expanding the application field of this material due to the increase in strength characteristics while maintaining an unchanged average density is of special interest. The guarantee of proposed solutions economic and technical efficiency is the transition from traditional portland cement to composite binders based on it. The article discusses the quantity and composition of the mineral supplements feasibility to optimize the binder properties of the problem peculiarities to reduce consumption of cement and chemical modifiers that increase the rate of curing and totals of non-autoclaved aerated concrete investigated compatibility issues between components to eliminate their negative impact on the formation of porous structure of the final product.
Abstract: Nowadays waste dumps of phosphogypsum take about 1500 hectares of fertile land and amount to 300 mln tonnes. Existing methods of processing are too labour-and energy-consuming, what didn’t lead to widespread use of phosphogypsum. Phosphogypsum waste continue to be stored in waste dumps, disperse on the wind and create ecological problem in the regions of storage. Authors of this article have developed non-burning technology of production of composite building materials based on phosphogypsum. Basic technology steps include: mixing of dry components in the temperature above 60°C, adding slacked lime, hydro-mechanical-and-chemical activation in the laboratory mixer in the temperature above 60°C, shaping and pressing under pressure. Economic efficiency of this technology is conditioned by usage of inexpensive raw materials (the basic component is phosphogypsum, which is finely dispersed bulk waste of chemical industry), reduction of energy and labour costs of building materials production. Currently in the Yu.M. Borisov’s VGTU center were conducted laboratory research of building materials based on phosphogypsum, completed work on technology parameters, and started tests for obtaining first industrial samples from composite materials with a usage of phosphogypsum.
Abstract: The paper presents new results in the building materials area. One of the solutions of the thin-walled elements obtaining can be achieved due to new additive using. The main purpose of the paper was improvement concrete properties for thin-walled constructive elements. The experimental and standard methods have been used and new complex additive for concrete. The research shows that a comprehensive additive consisting of aqueous solution of polycarboxilate polymer, silica sol and potassium nitrite is effective and makes it possible to produce high-efficiency concrete with unique properties: higher compression strength, higher crack resistance, frost resistance, water resistance, abrasion resistance. The study shows that the concrete is chemical resistant. Modified concrete can be recommended for manufacturing critical concrete structures of special purpose, for example high-rise constriction.
Abstract: A unique apparatus is described combining properties of plastometer and Vicat apparatus. A possibility is substantiated of cement properties plastometric determination, peculiarities are found of its compatibility with different action type modifiers in operation range of W/C values.
Abstract: The use of local natural and technogenic raw materialsallows expansion of the raw material base for producing the building materials and reduction of production cost. Creation of low energy-intensive technologies for producing the building materials is a priority for the construction industry. The chemical and mineralogical composition of industrial wastes makes it possible to use them for producing the low-clinker or clinker-free composite binders. Secondary resources can be used as an active mineral additive that would allow to reduce the cement consumption. The properties of cellular concrete depend on the formed cement matrix structure, the strength of the inter-pore partitions. Quality can be managed by directional formation of the mechanical framework. Providing the necessary granulometric composition of the cellular concrete components is decisive for the mechanical framework formation. The inter-pore partition structure in the cellular concrete is a developed silicate matrix formed by hydration products and a siliceous component. Therefore, when designing this structure, an analogy with ordinary dense concrete is quite possible. The basic principle for designing the concrete composition consists in creating a dense packaging of the constituent components.
Abstract: The article is devoted to the investigation of pipe-concrete prestressed structural elements with high efficiency. This is due to a more complete use of the strength properties of structural materials in the pipe-concrete beam. The article presents various methods for calculating pipe-concrete elements. The design of a concrete tube with a prestressed element using high-strength concrete is presented. The results of calculations of various designs are shown and the cross-sections of beams for perception of the same bending load are selected. A comparison is made between the consumption of beam materials of various designs. The effectiveness of the use of pipe-concrete elements for receiving bending loads made of high-strength concrete with prestressed reinforcement is shown in comparison with the construction of beams of traditional high-strength concrete, high-strength concrete pipe-concrete with no prestressing of reinforcement and metal beam, mass of the element, consumption of metal and concrete.
Abstract: Micro-fillers based on natural mineral wollastonite, modifying fine-grained concrete and improving its physical and mechanical characteristics, are developed and studied. The influence of the most common stabilizers on the aggregate stability of wollastonite-based microdispersed systems in the aquatic dispersion environment is considered. The optimal parameters, ensuring the production of micro-fillers in the form of stable suspensions, are developed. The application efficiency of the wollastonite-based filler due to its micro-reinforcing properties is revealed. These properties are specified by the formation of needle-shaped crystals by the ultrasonic dispersion in the aquatic environment, chemically related to cement-containing raw materials and contributing to the active selective adsorption of the binder hydration products. It has a significant influence on the rheological parameters of cement composites, on structure formation, as well as on their strength and deformation properties.
Abstract: According to modern standards, all courtyard, school and public playgrounds on which gaming equipment is installed must undergo tests of shock absorption of the surface under and around the equipment to prevent serious injuries to the child. In this regard, widely spread coatings on the basis of rubber chips. However, they not only do not meet the aesthetic requirements, but can also worsen the environmental situation when operating indoors. The paper describes a method for producing composites from wood flour and a silicone binder. The effect of wood meal content on the water absorption of composites as well as the effect of silicone content on the density of the results of the research showed that an increase in the content of wood flour significantly increases the water absorption of the resulting composite, that the composite material obtained with the addition of filler from wood meal, the values of the maximum and minimum elastic moment increased, since the presence of fillers imparts a restriction on the deformation of the composite, and, consequently, the composite becomes harder and harder. As a result of the studies carried out, it can be concluded that the use of silicone as binder and shredded wood waste as a filler makes it possible to obtain good quality elastic flooring with high aesthetic, operational and environmental properties.
Abstract: Improving the efficiency of construction composites is a relevant problem for modern-day material science. One of the ways to solve the problem consists in activating the binders by means of vortex-layer devices. Mathematical transformations produced a formula for calculating the dependency of the number of ferromagnetic-particle collision on the number and velocity of such particles, as well as on the device chamber fill factor. The results obtained by applying the proposed formula differ from D.D. Logvinenko's model by 10% at max. We calculated the impact force, the impulse of the grinding body in the vortex-layer device, as well as the amount of applied energy per unit of mass of the ground material. It was found out that the impact force and the impulse of force were maximized in the test device. At the same time, energy applied over the grinding time necessary to even out the binder dispersion in the vortex-layer device was 2 to 4.8 times greater compared to conventional devices.
Abstract: The paper discusses the importance of lightweight structural insulation concretes for large-scale and economical construction of residential and social buildings in the Republic of Crimea. Constructing buildings using structures made from lightweight structural insulation concretes is cost-efficient due to availability of the necessary raw material component in the Republic of Crimea. The paper also describes the composition and process of manufacturing lightweight structural insulation concretes from fired aggregate – foam-quenched culletа, gives a comparative analysis of thermal conductivity and water absorption, foam-quenched cullet test results versus other similar materials. Tests and calculations yielded conclusions about characteristics of lightweight structural insulation concretes based on foam-quenched culletе: high structural quality coefficient, increased thermal resistance, widespread availability and easy production of input raw materials for the manufacture of foam-quenched cullet, environmental friendliness with the possibility of industrial waste recycling, durability, and fire and biological resistance.