Measures to Improve the Durability of Enclosing Structures Regarding the Influence of Vapor Permeability and Condensation of Air Moisture

Kuz'menko Yuliya Evgen'evna ORCID: 0000-0002-6892-1055 Researcher, Siberian Federal University 660041, Russia, Krasnoyarskii krai, g. Krasnoyarsk, ul. Pr. Svobodnyi, 79 yul.kuzmenko@mail.ru Other publications by this author

Condensation of air moisture in structures and their subsequent humidification is the main factor that significantly affects the service life. It is the enclosing structures that represent one of the most important components of any building and structure. To date, it has long been known that along with an increase in the humidity of materials, a decrease in the thermal protection of exterior walls is observed and corrosion processes are significantly accelerated. The combination of these factors inevitably leads to a decrease in the durability of the materials used. It should be noted that this problem is most relevant in modern multilayer walls ^[1].

The increased humidity of the enclosing structures has a negative impact on the operation of buildings and structures. The structure, which is subject to temperature fluctuations and low protection from moisture, will last much less than the structure, the layers of which have a normalized humidity regime. As you know, water increases its volume when it freezes. Based on this, when water is in the insulation, the pores will expand during freezing, which will eventually lead to an increase in convective heat transfer and, as a result, a decrease in the resistance to heat transfer of the insulation.

Thus, the task of protection from moisture is becoming increasingly relevant in the modern field of architecture and construction. This is due to a deterioration in operational performance and a decrease in thermal protection during waterlogging of the structure. It is also important to note that the accumulation of moisture in the enclosing structures contributes to the deterioration of the microclimate in the interior, the growth of mold fungi and other products that are a source of allergic diseases. In addition, there is rapid destruction of materials from corrosion, insufficient frost resistance and moisture resistance. Based on this, the task of increasing the durability of enclosing structures by reducing the influence of vapor permeability and condensation of air moisture has a high degree of urgency and the need for its solution ^[2].

To date, there are many methods and means of combating this problem. In particular, a special role in solving this issue belongs to the methodological aspect, which reveals the issue of correct calculation, planning and design of structures, taking into account protection from moisture. The primary aspect in increasing the durability of structures is the need to use design standards for enclosing structures.

Assessment of compliance with the standards regarding the considered indicators is reduced to comparing the resistance to vapor permeability of the enclosing structure to the normalized one . At the same time, it must be at least the normalized value. Therefore, the following equality must be fulfilled:

(1)

In this case, the normalized vapor permeability resistance must be determined based on two conditions. The first of them is based on the conditions of inadmissibility of accumulation of moisture in the enclosing structure during the annual period of operation. Thus, the accumulated moisture in winter should completely disappear during the summer period.:

(2)

The second condition is that the amount of accumulated moisture must be less than the value stipulated by the SNIP by the end of the moisture accumulation period.:

(3)

Performing correct and high-quality calculations allows us to obtain the most accurate values necessary for the implementation of measures to protect enclosing structures from moisture. Based on the calculation of the values, it is possible to find the most optimal indicators necessary to determine the limiting conditions and interruptions for maintenance and repairs of structures. If the marginal condition of the repaired products is inefficiently determined, frequent failures and increased repair costs are observed. Based on this, performing correct and high-quality calculations is the main tool for achieving the durability of enclosing structures ^[3].

As can be seen, the task of increasing the durability of enclosing structures directly depends on a relatively large number of calculations. The innovative direction of development of this issue is the integration of digital and information technologies into the technological process. It is on the basis of these solutions that it is possible to automate the calculation processes and minimize the number of potential errors.

When solving the problem of increasing the durability of the structures used, the subtask of graphical wear tracking is actualized, the idea of which was proposed by the author Kupriyanova V.N. and Ivantsov A.I. in the study of the durability of multilayer enclosing structures (Fig. 1) ^[4]. In this case, the quantitative measure of durability should be taken as the calendar service time until reaching the limit state.

Fig. 1. Dependence of wear on operating time

The nature of curves 1, 2, and 3 in Fig. 1 is determined by mechanical, physical, chemical, or biological aging processes of materials. Along with this, it is necessary to determine the following quantitative indicators of the durability of enclosing structures (Fig. 2):

Fig. 2. Quantitative indicators of the durability of fencing

constructions

Taking into account the known dynamics of changes in the operational properties of materials in the structure, it is possible to determine its service life according to the developed scheme of wear dependence. This figure also shows the dependence of wear and service life on the aging curve. Based on this information, it is possible to ensure a given service life of the structure based on tracking the curve and taking appropriate measures when approaching scheduled repairs. It is important to note that in order to implement measures to increase the durability of enclosing structures, it is necessary to understand the basic properties of the functional layers for each individual type of fence (Fig. 3):

Fig. 3. Properties of functional layers of fencing

The information presented above allows us to compile a list of priority tasks aimed at determining the durability and service life of multilayer enclosing structures. These tasks are directly related to the establishment of a list of parameters of operational impacts, patterns of aging processes of materials, testing of materials by modes, forecasting and many others. Figure 4 shows a detailed diagram that reveals the main measures necessary to determine the parameters and develop the most durable structural solutions ^[5].

Fig. 4. Measures for the development of enclosing structures

The requirements for accounting during testing are contained in modern technical documentation. It is important to note that the main disadvantage of these documents is the inability to effectively determine the assessment of moisture accumulation in enclosing structures separately by month in an annual cycle. This, in turn, significantly complicates the detailed analysis ^[6].

Based on this, it is necessary to improve the regulatory framework, which will increase the quality of building design and lead to an increase in the durability of enclosing structures. To date, attempts have already been made to develop proposals aimed at correcting sections on protection against waterlogging of enclosing structures. One of the solutions in this situation is to develop an express method for analyzing the dynamics of moisture accumulation in the enclosing structure. In this case, the calculation of the humidity regime should be carried out in the following sequence (Fig. 6):

Fig. 6. The proposal of the express method of dynamics analysis

Moisture accumulation

An express analysis of the moisture-proof properties of the enclosing structures allows us to answer the following key questions: the fact of whether moisture will accumulate in the enclosure; whether it is possible to waterlog the materials in the enclosing structure. It is the answers to these questions that make it possible to justify the choice of a constructive solution that meets each required moisture-proof property ^[7].

Thus, the main purpose of the presented article was to perform an analysis on the issue of increasing the durability of enclosing structures by reducing the effects of vapor permeability and condensation of air moisture. The author substantiates the relevance of the issue under consideration, as well as a comprehensive analysis of certain aspects of this research area.

As a result of the work, the main measures have been identified, the implementation of which is necessary to increase the moisture-proof properties of the structure at the design stage and further operation. In conclusion, it should be noted that the issues under consideration are of great importance in the modern construction industry. It is the implementation of the described measures that will help reduce economic costs and optimize the use of resources of construction companies ^[8].