Investigation of the effect of moisture permeability of "SPADAR SK-450" light plaster on the process of dehumidification (sanitation) of the aerated concrete base

Introduction. One of the methods of rehabilitation of masonry walls is to cover them with a layer of special plaster mortar, which is designed to: protect the masonry material from moisture; gradual removal of moisture from the masonry material through a layer of plaster in the form of steam. A very important parameter for facade plaster is its moisture permeability, that is, the ability to pass through moisture coming from the masonry material. In this work, a comparative study of two facade plasters was carried out: "SPADAR SK-450" light mineral plaster and heavy mineral facade leveling plaster (hereinafter referred to as FLP) according to their moisture permeability. Aim. Comparative studies of the effect of moisture permeability of plasters ("SPADAR SK-450" and FLP) on the effectiveness of the dehumidification process of the aerated concrete base. Materials and methods. For the study, samples of nonautoclaved aerated concrete with a layer of "SPADAR SK-450" light mineral plaster and FLP heavy mineral plaster were used. During the work, the following parameters were determined and compared: the change in the percentage of mass of the samples over time, after their water saturation; the change in time in the density of the water vapor flow through the prepared samples; the dynamics of changes in the moisture content of the plaster coating. Results. It was found that the density of the water vapor flow in the FLP plaster is maximum in the first 24 hours, followed by a dynamic decrease. At the same time, the density of the water vapor flow in the "SPADAR SK-450" plaster is almost uniform throughout the entire observation period with minor fluctuations. Conclusions. It has been established that the "SPADAR SK-450" light plaster is more effective as a sanitizing plaster mixture in comparison with FLP plaster, as it promotes uniform gradual removal of moisture from the aerated concrete base without a significant increase in its own humidity. The uniform removal of moisture from the base through the "SPADAR SK-450" plaster layer helps protect against the formation of salts migrating with moisture from the base to the plaster surface.