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No 7 (2025)
Статьи
25 years of the Association "The union of dry construction mixture manufacturers"
4-5
Drying and further quarry sand preparation for the dry building mixes production
Abstract
The results of calculations and tests of a drying unit,which include a drying and cooling drum, cyclones, fans, belt conveyors, a receiving hopper, a burner device, and a control system are presented. The drying drum drive new design and the conditions of the drying and cooling drums joint operation are considered. The dust emission at the fine sand drying for dry building mixes is determined. Solutions for further operation improvement of an equipment set for sand drying and preparation are proposed.
6-9
Numerical simulation of construction 3D printing process. Problems and solution methods
Abstract
The numerical modeling methods of the construction 3D-printing process with concrete are analyzed from the point of view of the variable geometry printed objects stability numerical simulation possibilities. The method of computational fluid dynamics (finite volume method) implemented in CFD-complexes (ANSYS Fluent, OpenFOAM, COMSOL) was found effective for modeling and process control. The method and CFD tools applicability to solve the printing process modeling and controlling problem is determined by the numerical simulation possibility of concrete mixture flow during extrusion and layers formation, geometric conformity and structures stability prediction, taking into account the mixture rheological properties (viscosity, yield strength and thixotropy) and their change in time. A distinctive feature of the developed generalized approach and the 3D printing process numerical model is the mixture rheological parameters usage. The requirements for the nomenclature and range of its values have been determined experimentally. As part of this approach implementation experimental studies of rheological behavior by shear rheometry were carried out for three types of mixtures. During the model elements 3D printing their quality and stability in dependence with the mixtures type and technological characteristics were assessed. As a result, the rheological behavior rational model of and the values range of visco-plastic mixture parameters ensuring its suitability for extrusion and layering is substantiated. These include effective viscosity and Bingham yield strength, which determine the mixture extrusion quality; static viscosity and plastic strength, static yield strength, on which the layer shape, preservation and the printed structure stability are depended.
12-20
Influence of print heads on the additive manufacturing process: material selection for printing, and ensuring design characteristics of building products and structures
Abstract
The design of material compositions for construction 3D printing is primarily aimed at meeting the design requirements imposed on building structures and products. The main design requirements are typically strength and deformation characteristics, durability over the service life, as well as the technological properties of materials that ensure high-quality production during the manufacturing of building products and structures. In the process of 3D printing, the most commonly used materials are dry construction mixtures, for which it is necessary to consider all stages of the technological process during composition design, starting from the dosing stage, to significantly simplify preparation. This paper examines the key aspects of the influence of print heads on the requirements for materials used in construction 3D printing, their technological properties, and the anisotropy of properties in construction materials and products. A review and analysis of various types of print heads is conducted, and the physical and mechanical processes occurring during printing are considered. The main technological factors affecting the physical and mechanical properties of construction materials and products are analyzed, which must be taken into account when designing compositions.
21-31
Investigation of interlayer bond strength in concrete 3D printing technology
Abstract
The advancement of concrete 3D printing in construction necessitates a thorough study of factors affecting interlayer adhesion, as it directly impacts the strength and durability of printed structures. The lack of sufficient data on the influence of mixture workability, aggregate type and ratio, and curing time limits the optimization of process parameters. Addressing these gaps will improve the quality of 3D-printed structures, expand their applications, and reduce defect risks. This study is crucial for the further development of additive manufacturing in construction, providing a scientific basis for refining printing methods. The aim of this work is to investigate the effects of fine-grained concrete mixture workability, sand fineness modulus, process interruption time, and curing duration on interlayer adhesion in additive construction. The results reveal key dependencies of interlayer bond strength on mix design and process factors: workability, sand fineness modulus, and curing duration under varying process interruptions. Optimal parameters for maximum interlayer bond strength in 3D-printed structures include a workability grade of Pk=3 and a sand fineness modulus of Mk=3. The observed effects are primarily attributed to chemical, diffusion, and adsorption adhesion mechanisms, with mechanical interlocking playing a secondary role. The findings indicate that the key approach to enhancing interlayer adhesion in additive construction lies in optimizing mixture composition, which governs hydration kinetics and material structure formation.
32-37
The history of cement development — from ancient times to modern innovations
Abstract
Retrospective of the building materials (namely cement) development from the 17th century to the present is presented. On October 21, 1824, D. Aspdin patented Portland cement – this date is considered to be the “birthday” of the modern cement. However, the composition and properties of that binder seriously differed from present. 200 years of research and testing, optimal components ratio studying, firing temperatur control, continuous improvement of cement production technologies and methods allows us to create more complex and durable structures. Russian scientists V.M. Severgin, E.G.Chelishchev, N.N. Lyamin, A.A. Baykov and others made a significant contribution to the cement development and its properties study. Currently, the Russian cement industry is a dynamically developing sector that is completely privately owned. There are more than 58 cement plants operating in the RF, which provide the domestic market with building materials and participate in export supplies.
38-43
Modeling of the process of the cement separation in the closed aerodynamic unit
Abstract
The process of energy capacity reduction and increasing of the productivity of the cement manufacturing technologies is closely related to the creation of the modern closed aerodynamic units (CAU) with recirculation, which allows achieving the effective separation of the high-dispersity materials. The purpose of this study is to simulate the cement separation process in a CAU consisting of separator, thickening agent and centrifugal collector. To achieve this goal, a methodology for calculating the probability interval of the final product granules in the main participants at all stages of the CAU operation is provided. The main conditions of the operating mode are established and the approach to solve the issues of the material separation under the conditions of the flow unit mode is proposed. Special attention is paid to the mathematical methods used to estimate the fractional emission of the small granules and calculation of the recirculated material. The studies include both analytical calculations and visualization obtained by means of charts of the granulometric composition of the final product for the various components of the unit. The obtained results represent the basis for the modeling and optimization of the cement separation process in the CAU, which ensures the reliable forecasting of the analytical materials and the further possibility of using of the new technologies.
44-49
Decarbonization of the economy – geophysical meaninglessness and economic disadvantage of combating the greenhouse effect (open source analysis). Part 2. Russia’s climate policy and its impact on the construction industry
Abstract
The international agreements, protocols and programs related to global warming, supported by the Russian Federation, as well as plans to combat greenhouse gas emissions, primarily carbon dioxide, recognized as the greenhouse effect main anthropogenic factor, are considered. The article analyzes the Climate Doctrines of the Russian Federation, including the Comprehensive Plan for the Climate Doctrine implementation, federal laws, regulations and a Strategy for long-term development with low greenhouse gas emissions until 2050 in terms of their impact on the construction industry development. The danger of striving to zero CO2 emissions and decarbonization for the construction materials production is shown. A positive example of solving the reducing greenhouse gas emissions problem is presented.
50-57
Energy-saving technologies in civil engineering of the Chechen Republic
Abstract
The existing methods and technologies of energy saving in civil engineering in the conditions of the Chechen Republic are considered. It is revealed that the main limitations of the energy-saving technologies and materials integration in construction are related to its cost increase. In this regard, methods of encouragement from government structures, government support of developers, financial programs, reduced taxation and other financial instruments should play the key role. It is proposed to use the alternative energy sources such as solar energy and deep Earth heat energy as an active energy saving system in the Chechen Republic. Developments in converting the city of Grozny districts to heating using the Khankalskoye field thermal waters have been known since the 1980s and seem to be very effective, as they do not require high costs for implementation.
58-62
Investigation of the hydration processes of magnesia stone from mechanoactivated caustic dolomite
Abstract
Alternative Portland cement binders with low carbon dioxide emissions are currently being developed. One of them is caustic dolomite, which has low activity of magnesium oxide. The increased activity of magnesium oxide by mechaonoactivation in vortex layer devices will allow high-hydration magnesite stone and improved physico-mechanical characteristics. In this study we investigated the caustic dolomite powder and magnesium stone based on it. The X-ray phase analysis of the Rigaku SmartLab diffractometer was used to determine phase composition and structure. The hydration products were confirmed by results from differential thermal analysis in the STA 6000.The structures morphology, density, and compaction degree were assessed by the Merlin scanning electron microscope. It was found that, as a result of the mechaonochemical activation of caustic dolomite, а densely packed crystalline structure of magnesite stone is formed with a reduced porosity value, reduced crystallite sizes and unavailability of shrinkage cracks, which is a consequence of high contact density of crystallizing phases, accompanied by a general increase in strength of the magnesia stone. It has been proven that the activation of caustic dolomite contributes to the intensification of the hydration processes and to the formation of spatially-linked microstructure of magnesia stone due to stable phases of three-pentaoxyhydrochlorides, to a reduction in the porosity of the stone by 1,69 times and to reduction in the size of magnesium oxide crystals of 20% - up to 20,6 nm.
63-71
Regularities of structure formation of composite materials based on polystyrene foam and lignin-containing waste
Abstract
This article discusses issues related to the formation of the structure of composite materials. The effect of using a single-component and combined organic filler in the composition of a composite is studied using IR spectral analysis. The mechanism of π-stacking interaction during the formation of an adhesive shell of a polystyrene foam granule is presented. The process of forming the macrostructure of a composite with the introduction of an organomineral binder is considered. To study the effect of nanosized additives on composites, the results of thermomechanical studies are presented using the method of measuring the deformation of uniaxial compression under the influence of a continuously acting load under conditions of heating the sample at a constant rate. The nature of the influence of modifying polystyrene foam granules on ensuring the dense structure of the material has been established. The introduction of modified polystyrene foam granules causes the ordering of the composite matrix due to the construction of a complex structure-forming system that plays the role of a framework. Based on wood-plant and polystyrene foam fillers, compositions of heat-insulating and structural heat-insulating materials with a density of 250–600 kg/m3, thermal conductivity of 0.035–0.135 W/(moC), compressive strength up to 2.8–4.5 MPa, bending strength up to 1.5–2 MPa were obtained.
72-79