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No 3 (2025)
Статьи
Tradition and innovation dialogue
Abstract
It is shown that the opportunity to bring the panel buildings facades expressivity in the city historical center closer to those being built on individual projects exists in the exterior wall panels production at the universal stand of CJSC Recon. The production of reinforced concrete products in the factory under strict control makes it possible to obtain very precise, clearly defined details. The degree of articles detailing depends on the reinforced concrete products molds designers’ skill. Properly designed and manufactured molds helps to obtain the smallest details. Created 25 years ago and constantly being improved, the flexible technology for the reinforced concrete structures in a non-stressed and stressed state production, including concrete delivery to a molding site, vibration and heating to obtain durable products is implemented using CJSC Recon universal stands. Examples of implemented architectural solutions in different the Russian Federation regions are shown.
6-10
The construction industry features development in modern conditions
Abstract
Key features that determine the dynamics and directions of the construction industry development are highlighted. It is shown that the sanctions impact on the imported equipment supply and maintenance and on import of the components for own equipment making contributed to the domestic equipment production and development as well as creation of the original solutions based on an affordable component base. Innovative companies engaged in the production reautomatization and the import substitution analogues or more advanced devices, mechanisms and robots making can help to cope with current tasks. The problem of the construction industry large enterprises loading, caused by decrease in the population purchasing power due to the mortgages rate growth, marked a change in market conditions. The increase in low-rise and individual construction volume dictates the need for the house kits production that can move after the facilities under construction. It is shown that mobile production sites for the precast reinforced concrete production are becoming a promising area, allowing production to be quickly deployed next to the construction site and then moved to a new facility.
11-16
Industrial housing construction enterprises automation
Abstract
Current state analysis of automation on reinforced concrete product plants is carried out. The Russian Federation technological sovereignty is aimed at creating its own technologies needed in various industry and economy areas. An automation stages overview of the reinforced concrete products technology is given. It is noted that dependence on imported equipment has forced the Russian Federation machine-building companies to manufacture missing machines and mechanisms, and in some cases, to provide comprehensive house-building plants and precast concrete plants with modern domestic equipment. Importance of the automation for the enterprises efficiency, quality and competitiveness improving is emphasized.
20-26
Organization of the technological department at the precast concrete plant
Abstract
The necessary actions to create a technological department for the precast concrete production or to increase efficiency of the existing department are briefly described. The author does not provide a set of rules and laws, but covers possible process improvements that will trigger progress in the department or in the company as a whole. With a general understanding of technological work in production, the basic principles of training a qualified specialist that meet the requirements of the main position file are clearly formulated. In conclusion expediency of creating a corporate training center or academy within the enterprise is given.
27-29
Structural system for precast-monolithic frames of residential and public buildings made of industrial panel-frame elements
Abstract
Due to the increasing types of special impacts on buildings and structures, which often have a dynamic nature, there is a need to improve structural systems to ensure protection against such impacts. Reducing the weight of load-bearing structures of building frames and increasing the static indeterminacy of structural systems are among the effective methods of protection not only under seismic conditions but also during special and emergency impacts. As part of addressing this issue, the article proposes a new rapidly erectable structural system for residential and public buildings, made from industrialized panel-frame elements in a precast-monolithic configuration. In this system, the building frame is assembled from precast reinforced concrete structures of two types: panel-frames in the form of inverted U-shaped elements and L-shaped industrially manufactured elements. The connection of these structures on the construction site into the building frame, within the plane of the panel-frames, is carried out using two types of platform joints and monolithic embedding of the upper parts of the precast panel-frame elements’ beams together with multi-void slabs. In the orthogonal plane of the panel-frames, the frame is formed by monolithic tie beams and multi-void floor slabs. The conducted assessment of the mechanical safety of the proposed structural system demonstrated its high resistance to progressive collapse under special impacts. A comparative analysis of technical and economic indicators, such as material consumption, cost, and transportation expenses, revealed significant advantages over buildings constructed using traditional panel systems.
30-36
Russia’s technological sovereignty ensuring
Abstract
The “Strategy for construction industry and housing and communal services development in the Russian Federation for period up to 2030 with a forecast up to 2035” noted the need to reduce the investment and construction cycle duration by at least 30% due to, among others, standard design and precast concrete construction mass implementation. Precast concrete buildings and structures construction is a system consisting of the engineering community various activities. Creation of a technical documentation unified system that can be used by any designers, manufacturers of precast concrete and builders themselves for the entire Russian construction complex is proposed. It is noted that precast concrete buildings construction, compared with monolithic construction, reduces construction cost by at least 20%; reduces construction time by more than half; reduces rebar consumption by at least 20%; reduces concrete consumption by at least 30%.
37-45
Mechanism of concrete frost destruction
Abstract
Theoretical substantiation and experimental confirmation of a low-modulus inclusions (particles) role, including closed air entrainment pores while concrete frost destruction and increase of its frost resistance is carried out. It is shown that the low-modulus inclusions evenly distributed in the concrete structure are a brake for the cracks formed during pore water freezing growth, thereby increasing the frost resistance of concrete. It has been theoretically proved that the proposed hypotheses describe the possible pressure formation and development processes during intrapore water freezing and are not a mechanism of the frost destruction. The essence of the frost destruction mechanism is the process of the cracks formation, accumulation and growth after volumetric stress field formation in the concrete structure, which average value exceeds the structure tensile strength. T.S. Powers hypothesis currently recognized as the main hypothesis cannot explain many of the theoretical and practical facts available accompanying the concrete frost destruction. The essence of the concrete frost destruction mechanism is revealed and described based on the modern science positions - fracture mechanics.
46-57
Self-healing in construction materials science: basic terms and implementation methods
Abstract
Statistic data on changes in the number of publications mentioning the studied terms are shown. The analysis of approaches to the formulation of a conceptual framework for describing the processes of the construction materials properties restoring including thermoplastic binders is carried out. The absence of unified terminology in the Russian scientific community has been established. It makes objective evaluating research results in this scientific field difficult. Terms and definitions are proposed to describe self-healing, self-healability, components resource potential, encapsulated modifier, reducing agent and defect neutralization. It is shown that the system of proposed terms has a fundamental basis – thermodynamic interpretation.
58-65
Ensuring frost resistance of water-dispersion compositions for use in construction
Abstract
The article collects information on current Russian and international standards for monitoring the condition of water-dispersion products during tests of their frost resistance. It provides information on polymer dispersions developed and manufactured by Khoma Company LLC in frost-resistant versions, intended for the production of construction compositions. The processes that occur during the freezing of such heterophase systems are explained. The article considers methods for imparting frost resistance to water-based construction finishing compositions (primers, paints, adhesives, etc.): the introduction of compounds that lower the freezing temperature of water, targeted selection of initial components in the synthesis of film formers, the use of technological methods for the formation of polymer particles of a certain size and structure, a decrease in the concentration of the main substance with simultaneous additional stabilization. The properties of model compositions based on styrene-acrylic dispersions that passed freeze-thaw tests in different modes are presented. The particle size of polymer dispersions, viscosity of the compositions, strength and water absorption indices of films formed before and after the tests are monitored. It is shown that the introduction of the developed stabilizing additive allows to effectively increase the aggregation stability under the action of negative temperatures. It is concluded that water-dispersion systems, even if the manufacturer ensures their resistance to freezing, require special attention to cooling in different modes.
66-73
Study of the influence of defoamers on the main properties of plasticized cement paste
Abstract
The use of self-compacting concretes has become widespread in recent years. To achieve high flowability in mixtures, highly effective polycarboxylate based plasticizers are used. However, the use of superplasticizers in self-compacting concrete mixes without adding a defoamer can lead to a well-known problem: increased air entrainment and the formation of air bubbles. This can cause deterioration in the surface appearance. This article presents studies on the effects of various defoaming agents and air-entraining additives on the basic technological and rheological properties of plasticized by polycarboxylate plasticizers cement pastes, made from a blended binder which includes Portland cement and a microfiller based on ground blast-furnace granulated slag, in proportions of 25% and 40% respectively. The aim of this study was to investigate the spread diameter, expiration time, and dynamic viscosity of the cement paste with and without chemical additives, as well as to determine the type of defoaming agent that was most effective. The results of the experiments showed that a glycol ester-based defoamer was the most efficient. This type of agent reduced the number of surface pores in the paste. Optical microscopy was used to measure the size of these pores. It was found that glycol-ether defoamers were the most effective when used in concentrations of 0.02% and 0.04% in a cement mixture containing ground blast furnace slag (25%) and a polycarboxylate plasticizer. These additives changed the size and number of surface pores. It was also found that increasing the content of glycol-ether additives increased the mobility of the cement paste, but did not change the viscosity. There was a slight increase in average density and decrease in pore size and number by 0.28–0.29%, respectively. The study showed that using a defoaming agent in combination with a polycarboxylic acid ester-based additive can help reduce consumption and enhance plasticizing effects, thus predicting concrete behavior during construction.
74-81