The authors of this article raise the issue of the correct selection of internal material for sandwich panels. The use of these structures is widespread in the construction of industrial facilities, so it is important to consider all the parameters of possible options for the optimal choice. The authors define the objectives of the article as the creation of an auxiliary comparative table with the parameters of the most popular thermal insulation materials for sandwich panels based on regulatory and theoretical information, as well as the formulation of recommendations for the use of a certain material depending on the specified conditions. Particular attention in the study is paid to such properties of materials as moisture resistance, flammability, durability, density and thermal insulation. It is also important to note that the article touches upon the cost issue, namely, market prices for sandwich panels are compared with the considered insulation materials of some suppliers.
Keywords: thermal insulation materials, sandwich panels, properties of materials, analysis of properties, moisture resistance of structures, density
We conducted experimental studies to determine the thermal conductivity of polyurethane foams with different structural parameters, such as cell type and size. The purpose of the study was to investigate the contribution of radiant heat exchange to the thermal conductivity of polyurethane foams. The studies were conducted using the ITP-MG4 thermal conductivity meter in two distinct versions. In the first instance, the thermal conductivity of polyurethane foam was measured without the inclusion of a foil layer, whereas in the second instance. The results of the studies demonstrated that, depending on the morphology of the foam, the contribution of radiant heat exchange to thermal conductivity ranges from 5.88% to 15.87%.
Keywords: cellular materials, thermal insulation, polyurethane foam, thermal conductivity, radiation, morphology
The presented article reveals the issue of using waste from the automotive industry of rubber products as one of the possible ways to improve the quality of asphalt pavement and, accordingly, reduce the number of repair activities and material costs for their implementation and increase the service life of the roadway. The tests carried out show that the asphalt-concrete mixture using a modifier based on active rubber powder demonstrates the best mechanical and operational characteristics. The strength and elasticity of asphalt concrete increases, as well as the abrasion resistance decreases, which leads to a longer use time of this web. Such changes in the characteristics of the roadway have a positive effect on the economic side of the issue. Improving the quality of the finished product increases the time intervals between repair actions, which reduces material and resource costs. The adhesion of the road to the rubber of cars is improved.
Keywords: asphalt concrete, asphalt mix, automobile waste, rubber crumb, modifier, active rubber powder
The article is devoted to innovative approaches to the use of environmentally safe polymer binders in the production of thermal insulation materials (TIM) based on vegetable raw materials. The relevance of the work is due to the need to replace traditional synthetic polymers such as polyurethane foam, polystyrene foam, and mineral wool, which in the process of operation emit toxic substances with cumulative properties. Research shows that the use of biopolymers and renewable resources, such as castor oil-based polyurethane resins and casein adhesives, can significantly reduce environmental burdens and improve material safety. Special attention is given to thermoplastic and thermoset matrices, their properties, and applications in composite materials. Thermoplastics such as polyethylene and polypropylene have high impact resistance and recyclability but are limited in application due to the difficulty of processing and high melting point. Thermoset matrices, despite their high strength and resistance to chemical attack, are molded only once, making them difficult to recycle. This article discusses the advantages and disadvantages of different polymer binders and their prospects in the context of environmental sustainability and the efficiency of thermal insulation materials. The research is aimed at improving the physical and mechanical properties of composites and optimizing production processes to create affordable and environmentally friendly thermal insulation materials.
Keywords: innovative approaches, environmentally safe polymers, thermal insulation materials (TIM), plant raw materials, biopolymers, renewable resources, thermoplastics, thermosetting matrices, environmental sustainability, physical and mechanical properties
The article presents the results of studies of the strength properties of heat-protective fiber-gypsum-cement-vermiculite-concrete (FGCPVC) composites with volcanic ash with a maximum grain size of 0.16 mm, polydisperse reinforced with polypropylene RS produced by Russeal and basalt fibers of the RNB-9-1200-4s grade produced by PAO Ivosteklo. Expanded vermiculite of the 0.16–5 mm fraction from the St. Petersburg Mica Factory was used. It was found that the efficiency of the SDO additive at a dosage of up to 0.2% is from 2.3 to 3.1% of entrained air per 0.1% SDO, further increase in the dosage is impractical. Polypropylene fibers do not have a significant effect on the strength properties of FGCPVC composites. Reinforcement of FGCPBB composites with basalt fibers increases the compressive strength by up to 16%, bending strength by up to 73%, the Rf/R ratio with equal compressive strength increases to 51%. Polydisperse reinforcement of FGCPBB composites with basalt and polypropylene fibers increases the compressive strength by up to 40%, bending strength by more than two (2.26) times, the Rf/R ratio with equal compressive strength increases to 65%.
Keywords: gypsum, portland cement, ash, expanded vermiculite, polypropylene and basalt fibers, composites, compressive and flexural strength
The article discusses the use of liquid chlorides of natural genesis to combat winter slipperiness. The aggressive effect of liquid chlorides on snow removal equipment, road structural elements and the environment as a whole is also studied. Methods for assessing the effect of liquid chlorides on metal and cement concrete are developed. The article presents conclusions and recommendations on the use of liquid natural chlorides to combat winter slipperiness on roads.
Keywords: liquid chloride, formation water, brine, corrosion rate, cement concrete pavement, winter slipperiness
The paper considers a method for obtaining gypsum foam based on various compositions of dry mixtures, including a foaming agent, various sorbents, and gypsum binder. Expanded vermiculite, perlite sand, and crushed expanded clay gravel were used as sorbents. The most effective sorbent of the above is the crushing waste from the production of expanded clay gravel. As studies have shown, foam gypsum with a density of 250 kg/m3 and a strength of 0.9 MPa can be obtained.
Keywords: Dry mix, adsorption, gypsum foam, gypsum binders, sorbent, expanded clay sand, vermiculite, perlite, foaming agent
The results of studies of the strength properties of polydisperse reinforced composites based on gypsum fiber cement binders are presented. The increase in compressive strength due to dispersed reinforcement reaches 16% at the age of 2 hours and 19% at the age of 28 days, with bending by 69% and 75%, respectively. The compressive strength level of at least 90% of the maximum strength value occurs with an l/d ratio in the range from 1100 to 1800. When bending, at least 90% of the maximum strength value occurs at any l/d ratio with a reinforcement coefficient of μ = 1.3%. When reinforced with basalt fiber in combination with polypropylene fiber, the compressive strength is 1.67 times. The increase in bending strength ranges from 2.17 times after 2 hours to 2.3 times after 28 days.
Keywords: gypsum cement binders, polydisperse reinforcement, composites, compressive and bending strength
The effect of gamma radiation on concretes of nuclear facilities and their components has been studied less than the effect of neutron radiation. In this regard, the purpose of this work was to assess radiation changes in concrete structures of various nuclear facilities under the influence of gamma radiation. The work presents computational studies of radiation changes in volume and compressive strength under the influence of gamma radiation in concrete structures of various premises of nuclear facilities. The calculations were performed using methods developed for the analytical determination of radiation changes in concretes and their components under neutron irradiation and heating. The rationale for their use was considered earlier. The calculations were based on the methods previously developed by the author for predicting radiation changes in fillers and cement stone under the influence of gamma radiation. It was found that under the influence of gamma radiation, significant radiation changes, especially in strength, occur and will occur in concrete structures of the considered premises of various nuclear facilities in most cases. Gamma radiation causes a decrease in volume and a decrease in strength, but it is different for concrete in different rooms depending on the absorbed dose rate. Radiation changes increase with an increase in the dose rate and the duration of operation. The calculated radiation changes in concrete under the influence of gamma radiation should be taken into account in the design, operation and especially when extending the operation of nuclear power facilities. However, the change in strength can be partially compensated by additional hydration and especially by an increase in strength due to carbonization. However, this is not taken into account in the calculations, since it has not yet been sufficiently studied. In this regard, the obtained results show the possible maximum effect of gamma radiation. Upon receipt of specific data on the effect of carbonization, the presented results can be adjusted.
Keywords: concrete, nuclear power facilities, nuclear power plants, gamma radiation effects, radiation changes in concrete, volume change, radiation changes in strength
Numerical studies of the temperature and humidity properties of three types of enclosing exterior walls have been performed using gas-silicate autoclave hardening blocks as the base, and a comparative analysis of the results of the study with the results of research by other authors has been carried out. The design features affecting the condensation of moisture in multilayer walls are revealed. It has been found that multilayer walls have a number of disadvantages that affect their performance and durability, in particular, the presence of materials with different vapor permeability and moisture absorption, which leads to the accumulation of moisture inside the wall. The prospects of using single-layer structures and the importance of choosing the right material for the finishing layer are shown. An example of the use of a finishing material based on acrylic and marble chips is given, and the need for further research of this material is shown.
Keywords: gas silicate block, condensation zone, plaster facade, finishing material, acrylic, marble chips
Toughening of requirements to buildings’ power efficiency enables development and implementation of modern lightweight concretes on efficient porous aggregates into building industry. The key demands to both lightweight heat-insulating and to fine concretes are ensuring low density index and thus low thermal conduction with high durability provided. There has been developed a lightweight heat-insulating fine concrete mix with the use of three fractions of granulated foam glass. To conduct the research there has been used a central composite design, which helped determine optimal consumption of separate fractions of granulated foam glass, and acquire a lightweight heat-insulating fine concrete with the lowest density. On the basis of obtained research results there has been carried out a calculation of thermal conduction ratio with the use of empirical formulae. The research results have been analyzed, and their descriptive statistics have been presented as diagrams and graphs. On the basis of the analysis of the research results there have been obtained regression equations and established influence degree of separate fractions of granulated foam glass on the density and thermal conduction ratio. There has been carried out an optimization of the material mix and the correlation between fine aggregate fractions calculated to provide the lowest average density.
Keywords: fine concrete, granulated foam-glass, thermal conduction ratio, average density, durability, experiment design, regression, mix optimization
The article analyzes modern approaches to the use of innovative materials to create an inclusive environment in residential buildings. The paper examines the main problems associated with the obsolescence of building materials, and offers promising solutions based on the use of adaptive and environmentally friendly technologies that enhance accessibility and comfort.
Keywords: inclusive environment, the problem of outdated materials, innovative materials, innovations, trends and prospects, bioplastics, carbon concrete, OLED panels, adaptive structures, accessibility, comfortable environment, design
The use of methods for strengthening soils with Portland cement makes it possible to increase the physical and mechanical properties of soils: strength, frost resistance, water permeability, etc. A technical understanding of the processes of structure formation in reinforced soils makes it possible to regulate the final properties and quality of the layers of highways. To describe the processes of structure formation, it is possible to use the theory of contact interactions and the theory of DLFO. The final properties of the reinforced soil are influenced by the following factors: mineralogy and specific surface area of the soil, water content, amount of cement, curing time and method of compaction.
Keywords: stabilized soils, structure formation of stabilized soils, stabilization with Portland cement, properties of stabilized soils
The relevance of the use of gas-filled concrete in construction is reflected. The problems of forming high-quality cellular structures are listed. It is noted that in aerated concrete, these problems are successfully solved by prescription methods, and to obtain high-quality foam concrete, it is necessary to take into account the energy characteristics of the interaction between the dispersed gas phase packed in foam films and the cement-sand slip. The most important factors of controlling the structure of foam concrete mixtures are revealed. It is proposed to consider foam concrete mixtures as a complex hierarchically multilevel system, the properties of which depend in a decisive way on the interaction between water and surfactant molecules. The process of moving surfactant molecules from the volume of the liquid phase to the gas-liquid interface is theoretically considered. The results of experimental studies of the effect of fiber consumption on the kinetics of plastic strength of mixtures, the density of the resulting concretes, and the measure of their loss of the dispersed gas phase during the phase transition from a viscous state to an elastic one are presented. Based on the experimental results and scientific generalizations, a conclusion is formulated about the causes and conditions for the preservation of the dispersed gas phase in the structure of foam concrete mixtures.
Keywords: foam concrete mixture, dispersed gas phase
The aim of the study was to determine the effect of the amount of alkaline hardening activator on the geopolymer binder consisting of ground blast furnace slag and fly ash. Ground blast furnace slag with fly ash was activated with sodium silicate (SN) at different contents of alkali solution (A). The results showed that an increase in the alkali activator content (SN:A = 5%:3% → 15%:4%) promotes an increase in the strength of concrete over the entire time interval of monitoring the strength gain. The addition of fly ash affected an increase in the compressive strength of concrete samples from 16 to 18% relative to the compositions without fly ash. Micro cracking is manifested in the compositions of geopolymer concretes without fly ash, activated by a sodium silicate solution at a higher silicate modulus. The reduction of the silicate modulus CH led to less microcrack formation and a more uniform structure, and the introduction of fly ash into the concrete mixture helps to eliminate internal stresses and the formation of microcracks on the surface of concrete samples.
Keywords: by-products, blast furnace slag, alkaline hardening activators, fillers, performance properties, strength, water absorption, development driver
The article deals with thea comparative analysis of frost resistance assessment results obtained from dry building mixes containing redispersible polymer powders and finely dispersed fillers of natural and technogenic origin, building mortars according to such freeze-thaw resistance criteria as change in ultrasound velocity and dynamic modulus of elasticity, compressive and flexural strength, and adhesion strength to concrete base. The composition of the mixtures is represented by the component ratio C:P:MD = 1:1.3:0.2 at W/C = 0.4. The number of freeze-thaw cycles implemented for the studied compositions, depending on the dosage of redispersible polymer powders, ranged from 100 to 125. Ffreeze-thaw resistance of the studied solutions is not exhausted according to the main standardized criteria. A positive effect of RPP on the freeze-thaw resistance of the contact zone is noted. The most “rigorous” criterion is the flexural strength.
Keywords: dry construction mixture, freeze-thaw resistance, strength, mortar, chemical water treatment sludge, redispersible powders
The use of ash and slag mixtures of thermal power plants in the structures of road coverings of highways makes it possible to significantly increase the volume of their reuse. One of the promising directions is their application in the compositions of stabilized soils. To assess the effectiveness of the use of these materials, such indicators as the cost of construction and the total thickness of the pavement structure are used. According to the results of the conducted research, it was found that the reduction in the total thickness of road clothing with layers of ash and slag mixtures of CHP compared with layers of traditional materials was up to 48%, the reduction in the cost of building road clothing structures using ash and slag mixtures is up to 21%.
Keywords: stabilized soils, ash and slag mixtures, road clothing, base of road clothing
The article reveals the topic of improving the processes of concreting monolithic structures. An absentee survey of respondents from among the existing manufacturers of works, construction control engineers and foremen was conducted. Information was obtained that is not always reflected in documentary sources or direct observation. The direct processes of transportation, feeding, laying and care of the concrete mix, as well as related processes, were monitored and analyzed.
Keywords: technologies, organization, technological process, concrete works, monolithic structures, operational control, construction control, economic potential
Optimization of the composition of heavy cement concretes modified with a complex additive based on industrial waste (alumina-containing component - aluminum slag (ASH), spent molding mixture (OFS) using the PlanExp B-D13 software package is a three-factor planned experiment, according to the criteria: compressive strength on the 2nd and 28th days of hardening.
Keywords: heavy cement concretes, fast-hardening concretes, optimization, experiment planning, strength indicators, industrial waste, spent molding mixture, aluminum slag
The article discusses the use of recycled materials obtained during the dismantling of facilities during renovation in St. Petersburg. The districts of St. Petersburg with "problematic" houses, such as panel "Khrushchev" and "ships" of the first type, are highlighted. Data on the types of waste, volumes of concrete scrap, features and applications of secondary rubble are presented. Examples of organizations in St. Petersburg dealing with waste recycling are given. The purpose of the work is to study the possibilities of recycling construction waste for reuse in construction and landscaping of the region.
Keywords: secondary materials, dismantling, renovation, concrete scrap, construction waste, recycling, crushed stone, sustainable development, St. Petersburg, ecology
Volcanic materials are widely used in the production of mixed cement. Volcanic tuff, as a mineral additive to Portland cement, is effective in improving the rheological characteristics of the hydraulic binder, has medium pozzolanic activity, improves the properties of the material and can be used in the composition of light plaster mixtures.. The purpose of the studies presented in the article was to form models of such mixtures that allow their properties to be assessed. The experiment was conducted on the basis of methods of mathematical planning, statistical processing of the results and analytical optimization of the obtained regression equations. The experimental studies are based on the matrix of a complete three-factor experiment. The composition of the light plaster mixture included the following components: hydraulic binder, crushed volcanic tuff (as a fine light filler), reinforcing fiber and synthetic additive. Compositions of plaster mixtures based on volcanic tuff have been developed. The optimal values of the main components of the plaster mixture based on volcanic tuff, which is present in the composition of the mixture as a light fine filler and as a component of a hydraulic binder, have been established. An engineering interpretation of the simulation results is given.
Keywords: plaster material, volcanic tuff, pozzolan activity, mathematical modeling, analytical optimization
The article presents the study of thermal conductivity of a promising building material “Corrugated veneer”, presents the sequence of the study, develops an installation for research, obtains the thermal conductivity coefficients of the material “Corrugated veneer”.
Keywords: wood materials, finishing materials, building materials, board materials, veneer, laminated wood
the modification of a thermally cured epoxy binder is considered due to the introduction of a plasticizer and a latent component digital and statistical methods of experimental research are used digital models linking the basic properties with changes in variable factors are obtained and an analytical technique for predicting the properties of products as well as the selection of their composition is developed a composite epoxy binder is obtained and studied.
Keywords: digital model, synthetic binder, latent component, regression equation, analytical optimization
The article presents the calculation of reinforced concrete column reinforcement using a metal cage made of angles, taking into account the physical nonlinearity of materials within the framework of the Lira CAD software package. The use of a nonlinear approach is due to the inability of linear methods to adequately reflect the real behavior of concrete and steel under load, in particular, their destruction and gradual loss of rigidity. This paper presents a model that takes into account the nonlinear stiffness characteristics of concrete and steel in accordance with regulatory documents. Taking into account the physical nonlinearity of materials when calculating column reinforcement is critically important for reliable modeling of the structure's behavior and preventing underestimation of the risks of destruction. It is necessary to check the structure for local destruction at each stage of loading to ensure the reliability of calculations and the safety of the structure. The use of specialized software with the ability to stage-by-stage loading and checking for local destruction allows you to obtain accurate results and justify optimal design solutions.
Keywords: columns, reinforced concrete, steel, strengthening, jacket, calculation, physical nonlinearity, software package, stresses, strains
The influence of the aluminosilicate component on the properties of mortars and concretes is considered. Special attention is paid to the addition of perlite dust to the cement binder and the use of the Polyplast SP-1 superplasticizer to regulate rheological properties. It has been experimentally established that an increase in the perlite content increases the water demand and reduces the fluidity of the mixture due to its high specific surface area and porous structure. The rheological properties of various formulations have been studied using a rotary viscometer. The results show that the addition of a superplasticizer reduces viscosity and improves fluidity, which is especially important to prevent deformations and internal stresses in hardening systems.
Keywords: technogenic raw materials, perlite, aluminosilicate component, building mortars, concretes, rheological properties, superplasticizer