Introduction. Basalt thermal insulation is widely used in the construction of buildings and structures due to its main indicator — non-flammable material. The object of the study are fifteen specimens of basalt thermal insulation laminated with foil, which are actively used in the construction market for thermal insulation of buildings, engineering solutions for fire barriers and fire resistance of structures, air ducts and cable penetrations.

Purpose of the study. The purpose of the study was to identify materials in the category of “non-combustible material” among the fifteen specimens presented.

Methods of the study. Control tests for incombustibility were carried out in accordance with the requirements of GOST 30244–94 “Building materials. Methods of testing for combustibility”.

Results of the study. The studied materials are layered in structure; therefore, all layers were studied separately (basalt fibre and foil with glue residues). As a result of the tests, it was found that thirteen of the studied materials do not meet the requirements of incombustibility, and only two materials turned out to be incombustible, that is, they fully comply with fire safety requirements and can be used without restrictions. Of the specimens that showed unsatisfactory results, three materials were made of non-flammable components, but the combination of aluminum foil and silicate glue led to an aluminothermic reaction in which the temperature in the chamber reached values above 1,000 °C, due to the failure of the thermocouples, the experiment was stopped. Research should be continued on the basis of a large specimen of statistical data for various materials from combined layers, an addition should be made to the regulatory documents on the test method for flammability, that when testing a multilayer material, it is necessary to test not only each layer separately, but also the entire material completely, since the combination of various, albeit non-flammable components, it can lead to additive effects and, as a result, belongs to the group of combustible materials.

Introduction. In recent years, the popularity of wood and composites based on it as building materials has been steadily increasing due to their availability and ease of further processing. According to Rosstat data, in 2020, record figures for the construction of houses from wood were reached, amounting to 9.35 million m2. However, wood is highly flammable, which severely limits its use in construction and other applications. Therefore, research on its fire protection is relevant.

Aims and objectives. To investigate the fire-retardant efficiency of the developed nitrogen-phosphorus-containing fire-retardant compositions (FRC) for wood obtained by chemical degradation of polyethylene terephthalate (PET) waste with and without aliphatic amines.

In order to achieve the objective, the following tasks were defined:

1. To obtain fire-retardant compositions for wood based on nitrogen-containing degradation products of polyethylene terephthalate with di- and polyamines and without the presence of PET.

2. To study the fire-retardant efficiency of the newly obtained fire-retardant compositions for wood.

3. To compare the fire-retardant effectiveness of fire-retardant compositions obtained with and without the use of polyethylene terephthalate.

Methods. The objects of the study were fire-retardant compositions for wood based on aminolysis products of polyethylene terephthalate by aliphatic amines. The method consisted in determining the mass loss of a wood specimen and the time of independent combustion when it was tested in the “Ceramic Tube” unit.

Result and Discussion. As a result of the conducted research, it was revealed that the obtained fire-retardant compositions based on the products of chemical destruction of polyethylene terephthalate at the consumption of more than 160 g/m2 belong to the first group of fire protection efficiency.

Conclusions. The developed fire-retardant compositions for wood on the basis of products of chemical destruction of polyethylene terephthalate waste have high fire-retardant efficiency. It is most expedient to use the composition based on PET – PEPA as FR for wood. It is established that the developed composition belongs to the first group of fire protection efficiency.

Introduction. Utilization of rice husk (RH), a multi-tonnage waste product of agricultural production, is of practical interest as synthesis of wollastonite and diopside-containing fillers on its base has great prospects. Phase composition and properties of these calcium and magnesium silicates (CMS) obtained by the method of solid phase synthesis will depend on the content of amorphous silicon dioxide in the products, their porosity, acid-base properties of surface, and others.

The aim of the research. To evaluate the impact of the method of obtaining silicon dioxide from RH on the properties and phase composition of silicates synthesized on its base.

Materials and methods of the research. In the work, the derivatives of rice husk processing were investigated: rice husk ash obtained in the laboratory conditions at 500 °С and industrial carbonized rice husk. X-ray diffraction quantitative analysis was carried out on the Rigaku SmartLab diffractometer. Specific pore surface was assessed by the method of low-temperature adsorption on the Quantachrome Nova 1200e apparatus. The pH of the aqueous extract of the specimens was evaluated by the combined measuring device solutions “SevenMulti” under the по GOST 21119.3–91. The carbon content was estimated on the element analyzer “CKIS 5E-CHN 2200”.

Results and discussion. Rice husk ash produced in the laboratory conditions at the temperature 500 °С and industrial carbonized RH are substantially different in porosity, while CMS on their base have different phase composition. Considering both derivates of RH, the largest yield of diopside occurs at the excess amount of dolomite. However, when the industrial specimen is used, the composition of obtained silicate also contains wollastonite, apart from diopside, and such CMS is characterized by the increased porosity of structure.

Conclusions. At the application of more porous industrial silicon dioxide synthesized by solid phase method, the silicate contains wollastonite, which is absent in the composition of the final product on the base of rice husk ask obtained in the laboratory conditions. All synthesized silicates contain crystalline silicon dioxides. The higher the content of silicon components in the stock charge, the greater the concentration of silicon dioxides.

Introduction. The application of modern computer technologies made it possible to achieve high practical and economic results in the construction of modern buildings and structures. This is due to the fact that modern software complexes allow to predict with sufficient accuracy the behaviour of building structures under the influence of various factors, including high-temperature influence. It should be noted that in the overwhelming majority of modern software systems, the most widespread are grid methods for solving the Fourier differential equation of heat conduction, namely the finite element method. The calculation result obtained using the finite element method depends on various factors that may not always be obvious when solving a particular problem, but in order to obtain the necessary accuracy of the solution, they must be taken into account in the modelling process.

Aims and Objectives. The aim of the work is to assess the convergence of the numerical solution of the Fourier differential heat conduction equation by the finite element method when performing the thermal calculation of heating of unprotected steel building structures within the framework of the development of design documentation for their fire protection, as well as validation of the obtained results of mathematical modelling with the known results of calculation and analytical solutions.

Methods. A steel column of I-beam section of profile No. 20 according to GOST 8239 was taken as a modelling object. Modelling of heating of the investigated structure by the finite element method was carried out without the use of fire protection when simplifying the dimensionality of the problem from three-dimensional to two-dimensional. Verification of the obtained modelling results was performed by the criterion of convergence of the numerical solution of the problem at the modelled time interval (60 min) at the sequence of meshes (three meshes with the number of degrees of freedom (DOFs): 200, 2,084, 7,102) and time steps (ten time steps: 0.05, 0.1, 0.5, 1, 2, 3, 5, 10, 15, 30 s). Validation of the obtained results was performed by comparison with the results of thermal calculations of steel structures, set out in the book “Calculation of fire resistance of building structures” by A.I. Yakovlev.

Results and Discussion. As a result of carrying out a series of thermal calculations of heating of the studied steel building structure with different grid steps and time steps, it was found that the modelling time step had a greater influence on the convergence of the obtained results than the grid step. At the same time, the change in the convergence of the obtained results in the studied time interval for all modelling variants occurred unevenly, namely: at the beginning of the modelled time interval, the difference of the obtained temperatures in the cross-section of the structure first increased and then decreased. Comparison of the obtained results with the results of thermo­technical calculations stated in the book by A.I. Yakovlev showed that the obtained average temperature in the cross-section of the structure was lower than the temperature stated in the book by A.I. Yakovlev, while the difference between the obtained times of reaching the critical temperature (450–750 °C) increases both with increasing the value of the critical temperature and with increasing the reduced thickness of the metal.

Conclusion. The assessment of convergence of the obtained results of modelling the heating of steel building structure by the finite element method and their validation with the known design and analytical solutions have shown that the application of the finite element method in the performance of thermal calculations within the development of design documentation for fire protection of steel building structures has its own features, which must be taken into account to obtain the required accuracy of the solution.

Introduction. Substantiation is presented and the direction for scientific research related to the study of new properties of the controlled system, in which a complex process of influence of the personnel of separate types of security and personnel of production structural units on the general state of the system of complex security is carried out.

Aim and objectives. The main objective is to develop a risk assessment methodology designed to improve the system of integrated safety at explosion and fire hazardous enterprises. To solve the three scientific tasks on the assessment of risks influencing the general condition of the system of complex safety, the following directions are defined:

• to solve the first task requires obtaining the results of risk assessment in the influence of personnel working at the enterprises on the general state of the system;
• to solve the second task requires the results of risk assessment of the impact of unimplemented measures on the overall state of the system;
• to solve the third task requires the presentation of validity for the results obtained by solving the first and second scientific tasks.

Methods. For the decision of problems use of expert methods which will allow to transform qualitative characte­ristics in a quantitative measure is grounded. The use of the method of prioritization used together with the Gauss probability distribution functional is justified. It is suggested to use a five-digit proportionally decreasing matrix for risk assessment in case of non-compliance with the requirements of normative legal acts (NLA) and normative documents (ND).

Conclusions. 1. The justification for the application of a group of expert methods, the use of which allows to obtain indicators of the impact of personnel working at enterprises on the overall state of the system of integrated security is presented. 2. The example, allowing to prove adequacy of use of group of expert methods, their possibilities in use in practice for an estimation of risks is demonstrated.

Introduction. Alarming trends in the statistics of fires in buildings and premises in recent years with large-scale consequences require the search and development of new methods and approaches in the field of early fire detection. A promising approach to low-inertia identification of fires is considered to be the use of intelligent systems based on visual assessment of fire hazard in the premises, based on various types of video cameras. Unlike traditional point fire detectors, this method is not limited by the volume of the room and allows detecting fires even in large open spaces and unpredictable movement of the flame front.

The aim of the research is to substantiate the feasibility of reliably identifying the fire source in a room at an early stage using video recording. The main task is to develop an algorithm for training a neural network module that allows for the accurate determination of the coordinates of the fire source location in a room at an early stage using video recording.

Materials and methods. Experimental studies were carried out using a 3 × 3 × 2.3 m room model with a gas analysis system, fire alarms, video recording equipment, and a control and monitoring system for collecting and recording information installed in it.

Results and Discussion. As a result of the conducted research, an approach to the use of video analytics for identifying the source of fires at an early stage was proposed.

Conclusions. Based on experimental studies, the optimal size of the pre-trained neural network model for the task was selected, and the feasibility of using a video surveillance camera for low-inertia identification of fires in premises was substantiated.

Examples of dust accumulation in various electrical installations are considered. A review of existing methods for cleaning electrical equipment from dust and other contaminants is provided. Explanations are given on the peculiarities of selection and preferred areas of application of individual cleaning methods. The possibility of cleaning electrical equipment without removing voltage is shown. A variant of using a combined method for removing contaminants is presented.