Introduction. String strain sensors, or string-type strain gauges, are high-precision devices designed to measure deformations in various structures, including concrete. These devices are widely used in the monitoring of constructions. The operation of these sensors is based on measuring changes in the resonant frequency of a taut string depending on the applied forces, which allows for precise determination of deformations in structures. This article presents the theoretical justification for determining the natural vibrations of a string depending on the tension force and applied forces.

Aim. The objective of this work is not only to analyze the theoretical behavior of the string sensor and describe the vibrations of the string, but also to evaluate the stress-strain state of the device under the influence of forces. Another goal of the work is to verify the consistency of the theoretical results with the actual data obtained from string sensors, compared with numerical experiments conducted using a finite element model of the sensor. Despite the long-standing use of string sensors, such studies in similar conditions, taking into account the specific nature of the problem and types of structures, have not yet been conducted.

Materials and methods. Analytical calculation methods and the finite element method were used to assess the stress-strain state of string sensors. To verify the theoretical solutions, calculations were performed using the ANSYS software package.

Results. As a result of the conducted analysis, a mathematical model was developed to determine the resonance frequency of the string, and its vibrational characteristics were also investigated. Additionally, the calculations were verified using the ANSYS software package, and the theoretical data were compared with actual measurements, which confirmed the high accuracy of the calculations. The results presented demonstrate good agreement between the theoretical models and real data, confirming the reliability of the method and its applicability in monitoring stresses in the reinforcement of reinforced concrete structures.

Conclusions. Thus, the use of string strain sensors for monitoring stresses in the reinforcement of reinforced concrete structures represents a promising and effective method. This work, including the verification of theoretical calculations against actual data and the validation through finite element modeling, confirms the reliability of the developed method for calculating the stress-strain state of the sensors. These sensors provide accurate data on stresses in the reinforcement and can be used for longterm monitoring in various structures, enhancing the safety and durability of the objects.

Introduction. The production of large-sized modules is fraught with technological difficulties, such as the risk of cracking during heat treatment, the heterogeneity of the concrete structure and the need to achieve high early strength for demoulding and transportation.

Aim. Optimization of the formulation parameters of the technology of concreting of the large-sized panels, taking into account the provision of the required characteristics of both heavy and light concrete for up to 5 days from the moment of their manufacture under a given heat and humidity treatment regime.

Materials and methods. Formulation optimization: selection and modification of the concrete composition using modern chemical additives (superplasticizers, hardening accelerators), microsilica and fly ash to improve workability, strength and density of the structure. Concreting of the structures is a key stage of the entire production line, as it is the longest stage, consisting of the sequential execution of certain processes. During the selection of materials, a large number of inert and binding materials, as well as various superplasticizers, were tested. A very significant list of manufacturers and suppliers made it possible to select batches of samples, followed by obtaining test results and identifying the appropriate suppliers.

Results. An optimized formulation of a high-strength and lightweight concrete mix has been developed, providing compressive strength of at least 70 % of the design strength for up to 5 days from the moment of manufacture, reducing the weight of the structure.

Conclusions. Comprehensive optimization of prescription and temperature-time parameters makes it possible to significantly intensify the technological cycle of production of reinforced concrete elements of large-sized modules without compromising their quality and durability. The implementation of the proposed solutions ensures a reduction in energy consumption, a reduction in the duration of the production cycle and an increase in the reliability of finished structures.

Introduction. This article is dedicated to a new, environmentally friendly, renewable material – hemp concrete, the production and use of which is currently growing, thanks to a number of studies conducted in the direction of studying the properties of this material. Concrete is one of the most promising and frequently used building materials, and its use is increasing every day to meet the needs of the rapidly growing construction industry. In the last decade, the growth of the construction industry, driven by rapid industrialization, has led to an increase in demand for concrete as a building material and, as a result, to the production of concrete on a large scale, which has consistently resulted in significant greenhouse gas emissions. While this is inevitable, it is important to explore alternatives to reduce the environmental impact of concrete. The relevance and novelty of this article are due to the systematization of most of the data on hemp concrete using modern literature sources from both Russian and foreign authors.

The aim of this article is to demonstrate the main properties of one of the environmentally friendly alternatives to conventional concrete, which is a building material made from hemp fibers, lime, and water.

Methods. The research methods used in this article are theoretical.

Results. The study was conducted on a theoretical basis, and as a result, the author has provided basic information about the properties and advantages of hemp concrete.

Conclusions. The research findings suggest that the composite material under consideration possesses several beneficial properties, including low cost, accessibility, thermal and sound insulation, low density, and resistance to carbon dioxide emissions, which have a positive impact on production.

Introduction. Increasing of the efficiency of using of the construction machinery, in particular, concrete mixers, is an important task of construction production, affecting the reduction of construction costs and increasing the efficiency of machine use.

The aim is to show the possibilities of the considered method of physical large-scale modeling for determining the optimal parameters of machines under given operating conditions.

Materials and methods. The optimal parameters of concrete mixers were determined by analyzing mathematical models of the working cycle duration of concrete mixers, the optimal solutions obtained were scaled to various operating conditions using the similarity theory discussed in the article.

Results. The article presents graphs obtained using the proposed methods, demonstrating the presence of optimal zones of efficient use of concrete mixers under certain operating conditions.

Conclusions. The considered provisions show that for concrete mixers, there are ratios between the main technical parameters m, N, q, T, l characterized by scale coefficients.

Introduction. This article examines international experience with shotcrete application in the construction industry. An analysis of the composition and application technology of the shotcrete mixture is provided. The development and production of molds for sample preparation is described. Samples were manufactured using the selected technology of wet shotcrete. The experimental studies were conducted in two stages: in the first stage, custom formwork was manufactured using additive technologies. In the second stage, testing of the experimental samples and analysis of the results were conducted in accordance with current regulations. The analysis of the results is presented in tabular and graphical formats. The effective thickness of the shotcrete load-bearing layer for the construction of engineering structures is determined.

Aim. To develop removable formwork for experimental studies of the thickness of the shotcrete load-bearing layer and study its effect on the strength properties of load-bearing structures.

Materials and methods. The experimental study was conducted in laboratory conditions using certified equipment in accordance with existing regulatory documents.

Results. A collapsible formwork design was developed for the laboratory samples with varying thicknesses of the shotcrete bearing layer creation, and a shotcrete mix formulation was selected. Based on the results, the strength of shotcrete samples with different thicknesses was compared. The bearing layer thickness for engineering structures was determined, and recommendations for the appropriate shotcrete layer thickness for linings, engineering structures, and civil buildings were provided.

Conclusions. A collapsible formwork design for experimental samples was proposed. The experience of the shotcrete application in construction was taken into account during testing. Analysis of the experimental data showed that shotcrete performs similarly to conventional concrete, as confirmed by test results on 18 shotcrete samples with varying thicknesses and complies with current standards. Taking into account the formulation studies conducted, additional testing is necessary for fiber-reinforced shotcrete.

Introduction. In the modern world, the issues of sustainable development and rational use of natural resources are becoming increasingly relevant. One of the main directions in this area is the use of recycled materials in various sectors of the economy, including construction. The construction industry, being one of the most resource-intensive sectors, has a significant impact on the environmental situation. The need to reduce the negative impact on the environment leads to the search and implementation of innovative approaches to the production and use of building materials. In this regard, recycled materials, which are waste products of production and consumption, are becoming a valuable source of raw materials for the construction industry. This article discusses the theoretical and practical aspects of the use of secondary resources in construction. The advantages and disadvantages of using recycled materials are analyzed, as well as promising areas of research and development in this area. Special attention is paid to the issues of economic efficiency and environmental safety of the use of the recycled materials in construction.

Aim. Analyzing the possibilities of using of the recycled materials in construction and developing of the recommendations for expanding of their using, taking into account the economic, social and environmental aspects of sustainable development.

Materials and methods. This study, aimed at exploring the possibilities and prospects of recycled materials using in modern construction, is based on a comprehensive methodology that includes an analysis of existing theoretical developments, regulatory documentation, empirical data, as well as the results of experimental and practical research in the field of the use of recycled materials in construction. The results were summarized and systematized, which made it possible to formulate conclusions and recommendations for expanding the use of recycled materials in the construction industry.

Results. Data on the current state of the use of recycled materials in construction are presented, the main problems are identified and ways to overcome them are proposed.

Conclusions. The introduction of the principles of sustainable construction, in particular the use of recycled materials, will make it possible to create economically efficient, socially significant and environmentally safe facilities. To successfully realize the potential of recycled materials in construction, a comprehensive solution is needed, including the development of a regulatory framework, stimulating innovation, raising awareness and changing consumer preferences. Only with the joint efforts of the state, business and society it is possible to create a sustainable and environmentally friendly construction industry.

Introduction. The need of the construction complex for resource conservation is briefly noted. It is shown that the demand of buildings for thermal energy depends on the stability of the properties of the enclosing structures of buildings under operating conditions. A scientific analysis of the ability of modern types of cellular concrete to absorb moisture has been performed.

Aim. A scientific analysis of the ability of modern types of cellular concrete to absorb moisture has been performed. The most important reasons for autoclaved aerated concrete of D500 and below grades are listed, which ensure their increased tendency to moisture accumulation under operating conditions and form negative consequences for housing users.

Materials and methods. The features of single-stage aerated concrete technology that control the degree of closure of their gas pores are described.

Results. The results of experimental studies reflecting the effect of the length of polypropylene fiber on the rate of phase transition of aerated concrete mixtures from a viscous state to an elastic one and the ability of hardened aerated concrete to absorb vaporous moisture are presented.

Conclusions. It has been established that only a single stage technology allows for the production of dispersed reinforced aerated concrete mixtures in turbulent mixers, which have a permeability comparable to that of brickwork.