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.

The use of mineral additives allows you to modify the properties of concrete and result in substantial economic benefits. The research the influence cement type with calcareous fly ash (W) content in cement, method of cement production, activation by grinding calcium fly ash and batch of fly ash on the rheology, plastic shrinkage, air content, the setting time and heat of hydration of mortar are presented in this paper. The results show that cements produced by intergrinding of the constituents or blending with fly ash pre-processed by milling, are characterized by acceptable technological properties, not differing significantly from other currently used cements. It is not recommended to use cements obtained by blending with raw calcareous fly ash W. Calcareous fly ash used for the production of cement should be selected because of its properties. According to conducted tests, this criterion can be the volume density of the ash, which should be at least 900 kg/m3. The negative effect of calcareous fly ash used as an additive for cement on workability is considerably smaller than when it is used as an additive type II.