Tinko savybių kitimas veikiant rūgštiems krituliams

Abstract

Darbe nagrinėti tinko cheminiai ir fizikiniai kitimai, veikiant rūgščių kritulių ir neutralaus lietaus laboratorinių drėkimo–džiūvimo bei natūrinių bandymų metu. Nustatytas oro taršos poveikis sienų fasadų tinkui. Iš tinko išplaunamos ir neutralizuojamos laisvos kalkės, susidaro įvairių druskų, kurios telkiasi tinko kapiliaruose, ir priklausomai nuo išorės veiksnių kristalizuojasi, dehidratuojasi, taip pat ir yra svarbus tinko senėjimo ir irimo veiksnys.

Chemical analysis data on precipitation in the scientific literary sources show the increase of hydrogen ion (H1) concentration despite the considerable efforts of many European countries to diminish oxide emission into the atmosphere. When emitted into the atmosphere, oxides (especially sulphuric and nitric ones), under the effect of moisture and other admixtures found in the air, turn into sulphuric and nitric acids and thus together with precipitation return to the earth. Besides other climatic impacts, rendered building walls are affected by acidic rains. The paper aims at the analysis of the chemical alterations that take place in samples of rendering samples (i. e. in the 5 mm thick external layer) when treated with the climatic damping-drying cycle. The roentgenographic, physical and chemical tests were carried out after 0, 40, 100, 160, 200, and 250 damping-drying cycles. Due to the impact of precipitation on the plaster surface the portlandite gets washed off. The newly formed compo¬sitions, hydrosilicates, in their turn undergo disintegration. They may get entirely disintegrated and in the hard phase turn into loose silica acid jelly. Plaster resistance to external factors mostly depends on how long the system hardening under the required conditions. The research was carried out with the aim of improving the methods employed to guarantee the proper building facade durability.