Moisture Transport in Cellular Concrete Walls with the Connector for Thermal Insulation

Abstract

IntroductionThe authors of the present work analyzed the impact of high initial moisture level of cellular concrete walls on their drying rate as well as the dependence of that process on the diffusion resistance of external plastering at the disruption places (connectors for thermal insulation) and outside them. The carried out analysis was made for two-dimensional modeling of a solid envelope, which, to some extent, simplified the problem of heat and mass flow through the building elements. The drying process of walls having raised initial mass moisture content depends on various factors, including also local disruptions. The mentioned disruptions occur when we apply mechanical connectors of high thermal conductivity penetrating the insulation material (connectors with a steel core).The disruptions caused by mechanical connectors result in the condensation of water vapour on connector walls. The volume and character of the formed condensate depends on the material solution applied for the connector, the wall or thermal insulation. In effect, we are faced with disturbed transport and migration of moisture in the envelope structure in the vicinity of the connector. At the places where point thermal bridges occur, structural material of the wall or the interior of the rooms may be damaged.Local disturbances of moisture transport may result from the applied design solutions, work execution imperfections left after the execution of an investment project, or they can be related with building operation and maintenance. When analyzing the above issue, we are faced with a question whether the disruption of moisture transport effected by mechanical connectors for a cellular concrete wall and insulated in the ETICS system on the basis of expanded polystyrene will bring about any relevant local changes involving the transport of moisture.

Resistance of ETICS with Fire Barriers to Cyclic Hygrothermal Impact

“…The finishing coat of ETICS is the most vulnerable layer exposed to climatic factors [8][9][10][11]. Precipitation, solar radiation, and temperature differences may negatively impact the thermal-insulation system, causing a broad range of types of damage [1,[5][6][7][12][13][14][15][16].…”

“…In order to prevent the fast spread of fire, different provisions can be made, such as barriers of noncombustible material such as mineral wool around the openings, and horizontal isolation barriers around the buildings between different floors [4,7,9]. Parallel to the emergence of new recommendations, there are various technical doubts about the possible negative effects of such a combination [6][7][8][16][17][18][19]. One is the presumption that there may be cracks in the reinforcing and rendering layers due to the different thermal expansion of materials under the influence of external factors; another possibility is the discoloration of the facade, associated with the different moisture-absorption rates of thermal-insulation materials [6][7][8].…”

“…On this subject, various research papers were published [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]; however, there is practically no information about the performance of two different thermal-insulation materials during hygrothermal testing. Since fire barriers are an integral part of ETICS, it is very important to know what kind of testing method is being used to ensure that the building occupants can be kept safe and healthy.…”

Verification of External Thermal Insulation Systems with Composite Thermal Insulation and Different Renders in Effect of Hydrothermal Stress

“…Studies on the application of ETICS have demonstrated that the finishing coat is the most important because it is exposed to climatic variables and it is often the weakest coat of all the components of ETICS [8][9][10][11]. Precipitation, solar radiation and temperature differences may have a negative impact on the thermal insulation system, causing different types of damage [1,[5][6][7][12][13][14][15][16].…”

“…Parallel to the emergence of new recommendations, there are various technical doubts about the possible negative effects of such a combination. One of them is the supposition that there may be cracks in the reinforcing and plastering layers, due to different thermal expansions of materials under the influence of external factors, another possibility of discoloration on the facade, associated with different absorption rates of thermal insulation materials [6][7][8][16][17][18].…”