№ 5 (2025)

The Arctic territory development involves usage of insulation systems that are resistant to harsh climate. The advantage of polyethylene foam products is the ability to create seamless insulation shells that reduce heat loss through joints and maintain constant thermal resistance at extreme temperature fluctuations. The seamless insulation systems are particularly important in the Arctic region. The aim of the research is to adapt the polyethylene foam systems application to the northern territories climate. The research addressed specific tasks related to study of the polyurethane foam products properties, as well as the operational resistance of these products in subzero and alternating temperatures conditions. Full-scale tests of the polyurethane foam insulation systems were carried out at the North Pole conditions. This modification is especially important given the logistical and environmental constraints of the Arctic, where compact, durable and easily accessible materials can significantly reduce transportation and installation costs. It has been established that the material has a high operational resistance in the temperature range from minus 60 to +30 ^оC. The polyurethane foam shrinkage does not exceed 4 mm/m. When isolating significantly long objects the temperature changes in the material should be taken into account at designing joints and fasteners insulating elements. The results obtained emphasize the importance of considering thermal expansion and compression in large-scale applications in order to ensure compatibility of joint design solutions with the material behavior and maintain the thermal insulation system integrity throughout its entire service life. The properties of polyurethane foam made it possible to recommend products based on it both for use in insulation systems for residential and commercial facilities located in central Russia and in its northern territories. The seamless insulation systems are effective as for heat preservation as for creating comfortable conditions. In addition to high thermal protection characteristics, the use of foamed polyethylene helps to reduce operational energy costs and complies with the green construction principles, providing long-term economic and environmental benefits.

The problems of underground space development in the constrained conditions of existing production facilities are a complex geotechnical task and require a specific approach. The presence of weak engineering-geological elements significantly aggravates geotechnical works. The foundations bearing capacity increasing is always under the close attention of geotechnicians, designers and builders. The use of drill-injection piles, constructed with non-standard physical processes in most cases, solves many complex and atypical geotechnical problems successfully. To ensure the design load-bearing capacity of monolithic reinforced concrete grillages with defective piles, it is proposed to supplement them with drill-injection ERT piles with multi-seat extensions. Redesigning the entire pile field and all grillages, taking into account the test results of the experimental piles for bearing capacity, made it possible to ensure the design bearing capacity of the building entire foundation as a whole. It is shown that the lack of necessary step-by-step quality control and its negative consequences correction led to cost increase. It is recommended to exclude the possibility of such situations.

This study analyzes the physico-mechanical properties and features of organo-mineral soils containing humic substances in order to determine their potential for use in road construction. The patterns of formation of such soils in various climatic zones of Russia, where they occupy significant territories, have been studied. The classification of soils based on the quantitative content of humic components was carried out, followed by the determination of their granulometric composition. The article presents the results of experimental studies on strengthening soils with a high content of organic substances for their further use in road construction. The effectiveness of an integrated approach to strengthening humus-containing soils by using various binding components: cement, bitumen and polymer materials in combination with sand additives is investigated. The physicochemical processes of interaction between the structural elements of the soil and stabilizing substances have been studied. Optimal dosages of binders and moisture characteristics of soil mixtures for various types of organo-mineral soils have been established, ensuring maximum strengthening efficiency.

Issues related to the state and ways of improving the regulatory and technical base of Russia for the protection of building metal structures with paints and varnishes are considered. The relevance of this topic is due to the increase in the volume of use of building metal structures for the construction of various construction projects. Thus, over the past 5 years, the annual production of building metal structures in Russia has grown by 17.3%: from 5.2 to 6.1 million tons. According to forecasts, by 2026–27, production will increase by another 12.5%. Based on the results of the analysis of the regulatory framework, it was noted that general requirements are established for building metal structures in accordance with GOST 23118-2019. At the same time, to ensure the required service life, they must be protected from corrosion and other impacts in accordance with GOST 32290-2015, GOST 34667.2-2020, SP 28.13330.2017, SP 2.13130.2020. It was revealed that in the currently valid regulatory documents, when creating paint and varnish coatings, more attention is paid to issues of corrosion protection and fire protection. Issues of creating protective paint and varnish coatings with other special characteristics are not given due attention, and all aspects are reduced to a general description in separate individual regulatory documents, which are outdated. Thus, a number of difficulties may arise when choosing paint and varnish coatings for certain operating conditions of building metal structures due to the lack of recommendations for the use of modern paints and varnishes and coatings based on them, tied to the main regulatory documents. The analysis of the methodological base for monitoring and assessing the quality of paints and varnishes and coatings for building metal structures has been carried out, which has shown its insufficient development, consisting of: the complexity of assessing a number of special properties, due to the wide versatility of the existing equipment and tooling; the lack of reliable and accurate methods for current monitoring of the state of coatings during their operation. The tasks for the development of the regulatory and technical base have been defined: development of recommendations for the creation of protective paint and varnish coatings with special characteristics and having a relationship with the main regulatory documents in the field of protection of building metal structures; development of methods and devices for assessing the quality of paint and varnish coatings of building metal structures, taking into account the use of modern materials and the specifics of the operation of facilities; development of a methodological basis for assessing the current state of paint and varnish coatings of building metal structures. The article presents a description of the solutions developed to date for improving the regulatory and technical framework, protected by Russian Federation patents, for destructive and non-destructive methods of testing, quality assessment and forecasting the durability of paint and varnish coatings of building metal structures.

The study of adsorption phenomena at the interface of solids and aqueous solutions of surfactants is the basis for identifying the mechanisms of plasticization, water reduction and air entrainment of mineral-water systems. Obviously, the free surface energy of the solid phase plays a special role in these phenomena. In this work, the components of this energy (acid-base and dispersion) for various mineral materials (cement clinker and limestones) were determined by the wetting angle method, and the effect of aqueous solutions of plasticizing additives on this indicator was estimated. It was shown that in materials with a relatively high SiO₂ content, the acid component γ_s⁺ significantly prevails, while in materials with a low proportion of SiO₂ and an increased content of CaO+MgO, the basic component γ_s^– of the surface energy predominantly manifests itself. This allows us to estimate the efficiency of aqueous solutions of cement concrete plasticizers, which are strong anion-active substances that are intensively adsorbed on the surface of materials with a pronounced basic component. The wetting angle of cement clinker and limestones with aqueous solutions of industrial plasticizers of different nature was studied: “Polyplast Ligno” based on sodium lignosulfonates, polynaphthalene methylsulfonate “SP-1” and “PC-1701” – a modified polycarboxylate ether. It was found that the most effective of them was the superplasticizer “PC-1701”, which even at an insignificant concentration (0.1%) reduces the contact angle of wetting on the surface of medium-strength limestone by 29.3%.