Moisture transfer in outer walls with layers of different density

Abstract

The need to protect external walls from excess moisture to improve heat-shielding properties is an urgent task. If the outer wall is created from expanded clay concrete blocks, then the most interesting are the blocks created by layer-by-layer moulding, in which each layer can have its own given density. In such blocks, each layer has its own coefficients of thermal conductivity and vapor permeability, which allows you to select the required heat transfer resistance and vapor permeability of the outer wall for a specific region, taking into account the characteristics of the climate. The ability to have external walls with different material densities inside makes it possible to implement energy saving tasks in the building. The article discusses options for external walls made of expanded clay concrete blocks with layers with different densities and coefficients of thermal conductivity and vapor permeability. Changing the location of layers with different densities inside the blocks changes the local values of the vapor permeability resistance, which leads to a different nature of the movement of water vapor inside the wall in winter. It is good when water vapor does not accumulate in the wall; it does not condense and freely goes into the external environment. A dry wall is more durable, it loses less heat in winter. Changes in partial pressures at full saturation and with existing humidity inside the expanded clay concrete block for layers of different densities in winter are considered to determine the possible condensation from water vapor inside the wall. Layer-by-layer moulding of building materials improves their properties to increase resistance to heat transfer and to form a dry and more durable outer wall.